Balsa Finishing?

[captain26]

BAR with balsa fin/cone finishing question? As a kid, I didn't worry much with filling the balsa grain in fins and nose cones and if I did, not much. Build it, paint it and launch it! Next!

As a model builder again, I would like to finish my models to a higher standard and have gained good info from this forum. I am currently using the Elmer Fill/Finish product and have had good results, not great? It seems that no matter how many coats I apply, some grain remains - especially on a nose cone I'm currently working on. Does the balsa need to be sealed before the filling process starts? Seems like the balsa is soaking it up like a sponge? Thanks in advance for any advice/info!

[jharding58]

Yes, at some point you will need to seal the wood. Aerogloss Sanding Sealer or Balsa Filler in three coats with 400 grit between. Then a prime (I commonly use matte white to add good undercoat) then the main color probably in two coats. If you want to really have a slick fininsh then you would use a relatively heavy final coat for color depth. Then you will get into the clear coat converation.

[CPMcGraw]

For fins, I'm in the "self-adhesive label paper" camp. Stick it on, trim, and hit the outer edges with thin CA to seal them down.

For NC's and transitions, Kilz primer is a good method. You will sand much of it off, but what remains becomes a really good "skin" that can be polished with progressively finer sanding papers before the color shot is applied.

For final finishing/decal seal coating I use "FFF", or what used to be called "Future Floor Finish". I think it's been renamed to Pledge, but it's still the same stuff. The technique has been around since the stuff first came out. I airbrush it straight, no thinning. Works both as a decal surface prep, and as a decal sealer.

FnF is still a good surfacer, if just a bit messier. It's water-based, so you have to be careful on thin fins to do both sides evenly, otherwise the fin will cup with the grain as one side expands and the other doesn't.

[stefanj]

My preferred method:

A sealer like dope Sanding Sealer or Minwax Wood Hardener

(sand smooth)

Wait. Wait longer. Let that stuff outgas.

Elmer's filler, several coats, sanding in between.

Wait a bit. Let that water evaporate.

Prime, sand, prime, sand until it is smooooooth. If necessary, use thick gray enamel to fill cracks and dings.

Wait.

Several coats of paint. Wet sand out any problems.

Dry thoroughly.

Wet sand if necessary. Rub out any haze or imperfections with polishing compound.

Future.

Decals.

More Future.

Buff.

[jeffyjeep]

Personally, I use Aerogloss Sanding Sealer exclusively. The number of coats depends on the hardness of the balsa and on the desired finish. This Texas Firefly took 4 coats on the nose cone and fins.

[ghrocketman]

Here's my method that I have been using since 1977 (almost 35 years):

Phase 1)
3 coats of WELL-MIXED and STIRRED Aero Gloss Balsa Fillercoat with sanding between coats 2 and 3; coat two should be applied over coat one as soon as the solvents flash in coat one.
Sand coat two after an hour and apply coat 3.
After drying at least an hour, sand coat 3.

Phase 2)
After the sanded balsa fillercoat has dried overnight, apply two or more coats of Aero Gloss Sanding Sealer over the fillercoat, with sanding between coats after they dry.

Some apply the sealer before the fillercoat but that is BACKWARDS as the fillercoat FILLS much better over the raw wood.

Finished wood parts using this method can be topcoated with ANYTHING including butyrate dope. Using Elmers Water-based fill-n-finish results in a substrate NOT compatible with dope or "hot" solvent content lacquers. In addition, fill-n-finish makes a HIDEOUS DUST MESS when sanding which Aero Gloss products do not.

[captain26]

Great tips/ advice, thanks to everyone! I learned the hard way on my Nike X fins using the water based FnF. They are thin, fairly soft balsa and looked like Fritos when they dried! Glad I cut two sets, coated both sides at once on second set and they are fairly straight. As a couple folks noted, the FnF does make a dusty mess, had to move my sanding operation outside!

Is there a difference between Aero Gloss sealer and fillercoat or is it the same product?

[GregGleason]

Another method for sealing is using laminating epoxy. This is somewhat of an advanced technique, so I am only mentioning it as it is something that I do to seal balsa. If you add talc and/or glass microballoons to the epoxy, it helps to close up the tiny holes in the wood. Usually two treatments are all that is needed. This method as seen as overkill by some and it's use is certainly in the minority of builders. AFAIK, epoxy-based sealing methods will have no compatibility issues with either lacquer or enamel primers.

Also, on the topic of epoxy. Stay away from polyester and vinylester epoxies. There is some nasty stuff in them and those are the kind you typically find at home supply and auto supply stores. Aeropoxy and SYSTEM 3 by WEST are good quality epoxies, but there is a distinction made between laminating epoxies (which are quite runny for fiberglass or carbon fiber layup) and epoxy adhesives (which are thicker).

Regardless of whichever method you use to seal balsa, the final finish will be only as good as your primer coat. Good paint shows how good a job you did on sealing and priming.

Greg

[ghrocketman]

Fillercoat is different than Sanding Sealer.
Balsa Fillercoat is high-solids dissolved in Clear butyrate dope.
Sanding Sealer is plasticizers and hardeners mixed with Clear Butyrate Dope.
Finish one gets with fillercoat is smooth but porous and soft.
Sanding sealer "seals" and toughens the wood leaving it with a plastic like top coat.
One can use either or, but they work best when used together as a system.

[luke strawwalker]

BAR with balsa fin/cone finishing question? As a kid, I didn't worry much with filling the balsa grain in fins and nose cones and if I did, not much. Build it, paint it and launch it! Next!

As a model builder again, I would like to finish my models to a higher standard and have gained good info from this forum. I am currently using the Elmer Fill/Finish product and have had good results, not great? It seems that no matter how many coats I apply, some grain remains - especially on a nose cone I'm currently working on. Does the balsa need to be sealed before the filling process starts? Seems like the balsa is soaking it up like a sponge? Thanks in advance for any advice/info!

Here's what works for me...

First thing when I get a kit, I inspect the balsa nose cone/transitions for smoothness... some are really nice, some tend to be pretty rough, like the balsa 'tore out' when it was being shaped, and leave a 'scalloped' surface behind. If necessary, sand with 220 grit to get it pretty smooth and even, but I'd say 80% of the time this step isn't necessary.

Then, using some ultra-thin CA (I prefer the cheap stuff in the pink-labeled bottle from Hobby Lobby, which you can get with the 40% coupon on the weekly special) wet the surface of the nosecone down with the CA (do this outdoors and stand upwind or crosswind-- the fumes can be rather eye-watering!) and I usually start at the shoulder end of the nosecone (only apply to the part of the cone OUTSIDE the rocket, not to the nosecone shoulder itself, as it will *slightly* increase the diameter and require sanding down to fit the tube well.) Apply a thin, even layer all the way around the cone, usually twice-- the balsa will "suck" the stuff right into the wood fibers. This greatly strengthens the wood and seals the pores as well. Carefully set the finished nosecone aside to 'dry' for about 10 minutes or so, on a cardboard box or wax paper (so if any glue runs down, it won't glue itself to what it's sitting on).

This tends to raise the dust and loose fibers on the surface of the nose cone, so a light sanding with 220 grit will get rid of all this stuff and make the nose cone very smooth again fairly quickly.

Take your Elmer's carpenter's wood filler, and using a small baby food jar or suitable container, mix about a teaspoon of it with several drops of water, and work it up until it's smooth and about the consistency of hot dog mustard. You want it thin enough to BRUSH on, but not so thin that it's watery and makes bubbles... just about like bottled mustard. Using a 1" cheapy paintbrush, apply the thinned FNF to the nosecone/transition and set it aside to dry.

Sand with 220 grit, taking MOST of the filler back off. Reapply if necessary, let dry, sand it down with 220 again. By this time the cone should be about 95% filled and smooth. Sand again with 400 grit to make it slick... you just want to get it nice and smooth and ready for primer-- if you can see any defects at this point, now's the time to fill them with another spot application if necessary.

Give the cone/transition a couple coats of good filler/primer (I like Walmart Colorplace Hi-Dep Red Oxide Primer, but they quit making it, so now you can only get the regular gray primer, but it works well too, and of course Dupli-Color and other "high solids" primers will give you and excellent job as well, for more $$$. The main thing is, make sure the primer is compatible with whatever paint you plan to spray over it.

Once the primer is dry, sand with 220 grit, until it's as smooth as you can get it. If you sand through the primer anywhere trying to get everything smooth, reapply, dry, and resand. Once it's smooth, switch to "damp sanding" with 600 grit wet/dry sandpaper dipped in a bowl of water and shaken off, use just enough moisture on the sandpaper to prevent it from clogging. Sand the whole surface in small circles, moving constantly and overlapping the previous passes. Periodically wipe off the 'sanding mud' (primer dust mixed with water) with a damp paper towel. Hold the cone up to the light and sight down it like a gun barrel, and slowly turn it... the 'glint' of light off the surface should be smooth, even, and unbroken, not wavy or showing any other visible defects. This whole primer sanding and resanding may take 1/2 an hour to an hour to do per part, but it's worth it.

Wipe the finished part down with a damp paper towel to remove all traces of dust, and wipe down with a dry paper towel and set it aside to dry overnight. They'll be ready for paint in the morning.

Once spray painted, the part should look identical to a plastic part. I've been amazed at how smooth balsa can turn out with a little time and elbow grease using these simple methods...

For fins, the same methods can work, but it's MUCH simpler to simple glue a layer of printer paper to the fins to cover the wood grain... and it strengthens the fins SUBSTANTIALLY where simple FNF does not. I cut and stack-sand my fins to identical shape, sand in any desired airfoiling, then get a few sheets of printer paper. Cut a sheet of printer paper into pieces about 3 times the size of the fin... enough to cover both sides of the fin at once and still have at least an inch of paper all the way around the edges of the fin. In fact I usually lay the fin on the paper, about an inch in from the edge, with the LEADING EDGE of the fin toward the center of the paper, trace it lightly onto the paper, and CAREFULLY ROLL THE FIN OVER THE LEADING EDGE, and trace it again to give a "mirror image" of the fin. Apply a thin, even coat of WHITE GLUE (VERY thin, but even!) to the entire surface of the paper where the first side of the fin will be glued down, extending past the outline of the fin, and gently press the fin down inside the first outline. Apply a second thin layer of white glue to the exposed surface of the fin (yellow glue isn't really any stronger here and white glue is MORE than adequate to the job, shrinks less, and smooths out easier, and is preferable on paper/wood joints instead of yellow glue). Once you have a THIN even coat on the entire exposed surface of the fin, gently roll it over THE LEADING EDGE onto the other half of the paper. Use a Sharpie marker or other 'fat' round pen or object (Sharpie markers are darn near perfect to the task, though) and gently "burnish" the paper down tight to the fin, starting from the center of the leading edge and working toward the root and tip edges, and back toward the trailing edge-- rolling/pressing the paper down tightly against the wood, and working any excess glue toward the edges of the fin. Flip the fin and repeat the burnishing, finally burnishing the paper down to itself around the edges of the fins, and set them aside to dry (usually overnight-- I do this the same day I do the nosecone filling/priming/sanding).

When dry, cut the fins out of the paper with scissors-- cut down to within about 1/4 inch of the edge of the fin. Using a SHARP hobby knife, gently 'shave' the remaining paper off the edges of the fin down to the balsa on the root, tip, and trailing edges (the paper should be tightly glued to the leading edge and smooth) and presto-- finished fins ready to glue on the rocket, suitable for priming/light sanding/painting. Having the paper wrapped and glued over the leading edge eliminates the possibility of delamination from the airstream ripping past the fins in powered flight, and the paper EASILY doubles the strength of the fin (or more) while adding only VERY MINIMAL weight... works like a champ!

When done right, the whole rocket will look like it's made of plastic... :) Also, tube spirals and any other imperfections that need a bit more than primer to fill, I find that the autobody 'spot putty' sold in tubes at auto supply stores works MARVELOUSLY on... just dab a bit onto the spot, and sand it down smooth when it's dry. The stuff is basically primer solids with just a bit of lacquer thinner in it to make it a paste...

Good luck! OL JR :)

[Scotty Dog]

Here's my method that I have been using since 1977 (almost 35 years):

Phase 1)
3 coats of WELL-MIXED and STIRRED Aero Gloss Balsa Fillercoat with sanding between coats 2 and 3; coat two should be applied over coat one as soon as the solvents flash in coat one.
Sand coat two after an hour and apply coat 3.
After drying at least an hour, sand coat 3.

Phase 2)
After the sanded balsa fillercoat has dried overnight, apply two or more coats of Aero Gloss Sanding Sealer over the fillercoat, with sanding between coats after they dry.

Some apply the sealer before the fillercoat but that is BACKWARDS as the fillercoat FILLS much better over the raw wood.

Finished wood parts using this method can be topcoated with ANYTHING including butyrate dope. Using Elmers Water-based fill-n-finish results in a substrate NOT compatible with dope or "hot" solvent content lacquers. In addition, fill-n-finish makes a HIDEOUS DUST MESS when sanding which Aero Gloss products do not. I used regular wood sealers in the past on balsa ; "Last & Last" ,Minwax, Varnises and Poly sealers... thats what Dad had around the house. Some took along time to dry and some not so long. But they did SEAL very well. I agree with your info on Water based filler, I got me some Elmers FnF and I have had issues with the cell ends of the NC and edges of fins blistering. I would get a nice wet coat of paint on the NC and would watch as little pin head size blisters would pop out. Only thing I could make of it is a dif in temp when painting. I been takeing the parts out on to my sun-porch that may be only 40-50 deg ,shooting them, let set some and takem back in house. I guess its "gas/air" coming out on the balsa cell ends.I know if I had used a TRUE WOOD sealer this would not happen.Anywhoo-I ve had it with the mess and softness of the FnFs. Im going to get me some Aero Gloss Products. I have used Aero Gloss Products in the past. I built alot of balsa/tissue paper airplanes. Mostly rubber band man powered. Hm, I might just pick me up a simple airplane kit when Im at the LHS getting the Aero Gloss.

[Scott6060842]

Back in the day Elmers school glue and a can of half dried up Rustoleum swiped from the neighbor's garage was about as sophisticated as we got....

But as a recent BAR I am trying to do better. I have adopted GHRocketman's method of Aerogloss Balsa Fillercoat then Aerogloss Sanding Sealer. Simple with great results. Good point about STIRING the Fillercoat, I learned that the hard way. You can shake the bottle until your blue in the face, still won't mix right. I have been waiting 3 days between the last coat of Sanding Sealer and primer as recommended on the bottle.

Problem is so far I have been buying 1 oz bottles on ebay for about 5 bucks a crack. I am trying to get a little smarter about this and I found the 3.5 oz six packs on Hobbylink but they are out of stock until sometime in March.

Is 3.5 oz the largest size for Aerogloss and does anyone sell it in bulk?

[jeffyjeep]

ehobby.com and ACSupply both sell 3.5 oz. jars of Aerogloss by the 6 pack. ehobby is where I get mine.

I don't know why Aerogloss doesn't come in pint cans (like SIG does).

Jeff

[ghrocketman]

I Have Quarts and Pints of original Pactra Aero Gloss Balsa Fillercoat and Sanding Sealer from the 70's, 80's and 90's that I have stockpiled from old hobby shop closeouts in person and on ebay.

Other than from Sig or Brodak, Pints/Quarts have not been available since the early 90's (at least for Aero Gloss).
Brodak's dope is actually re-packaged Full-Scale Aircraft Randolph Dope. It is available in 3 times the colors that the Aero Gloss line was in it's highest point and is every bit as good.

Brodak's Sanding Sealer is almost exactly the same as the Aero Gloss product; the Sig stuff is usable, but only if you cut it about 60/40 Sealer to thinner; otherwise the Sig is far too thick and will form hideous outgassing bubbles.

As far as Balsa Fillercoat goes, I think the only source now is in small (3.5oz largest) bottles from Midwest under the Aero Gloss label. Fortunately, making your own Balsa Fillercoat is a snap. Take a pint or half-pint of Clear BUTYRATE (NOT Nitrate) Dope in a brand of your choice and dissolve a couple tablespoons plain unscented Talcum Powder and a teaspoon of "Plastic Wood" into a half-pint or double those amounts of solids into a pint of Clear dope. That IS Balsa Fillercoat.

[stefanj]

Bill:

By "plastic wood," do you mean that grainy brown putty stuff from Red Deveil, or its equivalent?

[Mark II]

Another vote for using laminating epoxy on balsa nose cones. For anything smaller than BT-50 I use it exclusively. For BT-55 to ST-18 (1.84") I first soak the wood as best I can with Minwax Wood Hardener. Wood Hardener seals but does not fill the grain but as the name indicates, it toughens up the wood. I let the hardener in the outer layers of wood cure for a couple of days, then lightly sand it and apply another treatment of MWH. After that, I hang it up for up to a couple of weeks to allow the hardener to fully cure inside and out. (The surface can feel dry and hard while the inner layers of wood are still uncured and soft.) I sand it again to get the roughness out after it cures, and then coat the cone with laminating epoxy as before. For large balsa cones, (2" and up) I usually just use Wood Hardener alone. The larger the cone, the longer it can take to cure, so I set it aside for awhile. I don't build fast, so this isn't a problem for me.

Large balsa cones tend to be quite smooth, at least the ones that I get typically are. Sanding the fully-cured hardened wood takes care of nearly all of the raised grain. Large cones can take up to a month, sometimes longer, to fully cure after a couple of treatments with wood hardener, but the result is worth the wait. Factor that into your timeline for completing the project. I apply some Delta Ceramcoat All-Purpose Sealer to fill in little pores or remaining grain. This sealer works well but isn't quite as hard as epoxy. It is easier than mixing up a bucket full of epoxy, though and the MWH has already done a very good job of making the wood dent-resistant.

If there are any problem areas on the bigger cones, I apply Aeropoxy Lightweight Filler to them. This is a two-part epoxy-based wood filler. It can be sanded fairly easily after it cures, but it fills the gaps or holes with very tough material, the hardest wood filler that I have ever used (including Dap Plastic Wood). For smaller nose cones, I fix any remaining problem areas with either Carpenter's Wood Filler or Bondo Spot and Glazing Putty. I may also use the aforementioned plastic wood for this, too, on small cones, but otherwise I reserve my plastic wood for repairing nicks, cuts and sanding errors in the edges of balsa fins. It is truly superb for that particular job.

For fins, I use either of two methods that have already been mentioned. Especially with small-pattern fins, I fill and seal them with Aerogloss products in the same manner that ghrocketman described. With larger, broader fins, I paper the balsa. I have had excellent results with using Reynold Freezer Paper for this. The paper resembles white butcher paper, but it has a thin and very smooth coating of plastic on one side. I use a craft stick or a plastic (Bondo) putty spreader to apply a thin, even coating of white glue to the uncoated side of the paper and then bond it to the fin. As soon as I do one side, I follow up as quickly as possible by papering the other side in order to minimize warping. I lay all of the fins on a sheet of wax paper on my smooth Formica counter or on a smooth table, cover them with another sheet of wax paper, and then pile a stack of smooth textured hardcover books on them. Since there's not much air circulation under the books, I give the fins 24 to 48 hours to get fully dry. I want them to be completely dry so that they won't develop any slight warps after I remove them from the press. I only use white glue for this, since it shrinks much less than wood glue. The plastic side of the freezer paper is primer-ready without any further preparation.

[ghrocketman]

Yes, that Dap/Red Devil grainy stuff in the can/tube which is powdered cellulose in a paste form mixed with Acetone and Toluene.
If you add some of that to the Talc dissolved in the clear dope, it fills even better.
Just don't add too much; like Cayenne Pepper, a little goes a LONG way.

ANY process that takes even a WEEK (let alone a month) to dry, I immediately dismiss as taking WAAAAYYYY too stinkin' long.
I'd sooner shoot Imron out of a NON-HVLP paint gun WITHOUT a fresh-air breathing supply before I would use any finishing materials that have any step resembling "wait a month for drying"

[Mark II]

ANY process that takes even a WEEK (let alone a month) to dry, I immediately dismiss as taking WAAAAYYYY too stinkin' long.
I'd sooner shoot Imron out of a NON-HVLP paint gun WITHOUT a fresh-air breathing supply before I would use any finishing materials that have any step resembling "wait a month for drying":chuckle: :chuckle: :chuckle:

Well, I did say that I usually took my time when I build. :rolleyes: But occasionally even I think that some of my waiting times are excessive. Minwax Wood Hardener does seem to need the time, though and I put up with it because it really really toughens up the balsa. I pay enough for balsa nose cones, so I want to make sure that they are reasonably durable. I have a 9.7" long, 2.34" dia. balsa nose cone that has survived more drops and falls (from up to 5 feet in height tip first onto a hard floor) than you can whip a launch rod at, and yet the worst damage that it has sustained are a couple of very small and superficial dings. So yeah, the long cure time can be a pain, but the ultimate results are amazing. I should point out that smaller nose cones don't take anywhere near as long to fully cure after the treatment. The really long cure times (on the scale of weeks) are for very large balsa nose cones. They are more costly to replace, though, so they are the ones that you really want to protect.

[ghrocketman]

Soaking the cones with a good penetrating coat of 30+ minute pot-life epoxy would do the same though, dontcha think ??
It would fully cure in a DAY, not a month.
If I let a project sit for a month, I lose interest in it usually.

[Mark II]

Soaking the cones with a good penetrating coat of 30+ minute pot-life epoxy would do the same though, dontcha think ??
It would fully cure in a DAY, not a month.
If I let a project sit for a month, I lose interest in it usually.As I wrote earlier, I do in fact use laminating epoxy on many of my nose cones. I tend to use the wood hardener mostly on the really big ones. They are the most expensive, and they need all the hardening that I can give them, so I pull out all of the stops when I build with them. Needless to say, these are for my big projects, which are only a small portion of what I build. And as I have also already mentioned twice now, the cure time for wood hardener on smaller nose cones is much shorter than that.

The laminating epoxy that I use does indeed soak easily, at least for a little way, into the wood. I usually give it as many as three coatings, sanding it down after each one. It cures hard in several hours, but I usually wait until the next day to sand it. It certainly helps, but it doesn't make them totally bomb-proof. I've had things puncture through the epoxy a couple of times. The coating can only do so much when the wood underneath it is soft. So far I have only used BSI 20 Minute Finish Cure epoxy on nose cones. If I did it with West Systems or Aeropoxy laminating epoxy, the coating might be even harder. I do use long-cure epoxy for structural adhesion, but I'd be afraid that it would be too hard to sand if I coated a nose cone with it.

I'm not saying that my method is the only way or necessarily the best way; I posted about it because it is my own way. I have used a number of other methods for filling and sealing nose cones before this, so I know how they go. One that I haven't, though, is the dope augmented with talc and a little plastic wood method that you described above. It looks interesting and is one that I'll have to investigate sometime.

[ghrocketman]

I was speaking of using structural, NOT laminating, epoxy to harden cones.
Good stuff like Aeropoxy or West System, NOT 50/50 hobby shop stuff that is loaded with fillers to make the mix even for those too challenged to use measuring cups.
REAL epoxy is far stronger than hobby store stuff, which is not all that bad.

My method of 3 coats balsa fillercoat followed by 2+ of Sanding Sealer will not result in a cone anywhere near as hard as an epoxy coated one. Mine look great but are a bit fragile. They will NOT survive bouncing off pavement without mangle marks. Then again, I dont do that to them.

[Solomoriah]

I've been getting darn good results by brushing thinned FnF over the fins and cone, sanding when dry, then priming and sanding with a dry-sand compatible spray primer. Doesn't make my eyes water, and it's cheap.

[Mark II]

I was speaking of using structural, NOT laminating, epoxy to harden cones.
Good stuff like Aeropoxy or West System, NOT 50/50 hobby shop stuff that is loaded with fillers to make the mix even for those too challenged to use measuring cups.
REAL epoxy is far stronger than hobby store stuff, which is not all that bad.Well then, we're more or less in agreement. I want to do that - apply something like a thin formulation of West System epoxy to some nose cones. I think you're right, they'll be much harder than they are with the epoxy that I use now. Being able to sand them smooth is going to be deal maker or deal breaker, but West Systems is known for their large assortment of additives and modifiers, so maybe they'll have something that I can add in to make it easier to sand without significantly weakening it. If it will penetrate well, that will be a bonus too, because it will help somewhat the issue of a soft wood core inside a thin hard shell. Otherwise once something gets through the armor, it has no protection. Toughening up the wood itself in addition to installing body armor is ultimately the best choice if you are going to use balsa, but the most effective and widely available method for doing that takes some time to do the job.

Let me reiterate yet again though that the longer cure times seem to be a factor only with large (e.g., BT-70, BT-80, etc.) balsa cones. With smaller cones, the wait should not be longer than a week at the most, and often more like 2 or 3 days or less. That doesn't seem like an excessive cure time. Many of us wait for similar intervals between paint colors. The builder doesn't have to use wood hardener, of course, but my own anecdotal experience indicates that it is highly effective.

[jetlag]

I like to use thin CA to harden/toughen up cones when I feel the need. Works well for overly soft fins, as well, like the wood that comes in The Launch Pad kits. And the weight penalty is minimal if not nil.
I use epoxy for everything else, though. Holds up a lot better than white/wood glues, especially in the heat we have here. Fins don't sag if the rocket is left on its side.
Works for me!
A-

[luke strawwalker]

I've been getting darn good results by brushing thinned FnF over the fins and cone, sanding when dry, then priming and sanding with a dry-sand compatible spray primer. Doesn't make my eyes water, and it's cheap.

Yeah, I agree...

I mean, to each his own, if it works for you and you enjoy it go for it, but looking at some of the prices folks have talked about for these sanding sealers and dope and stuff, and the fumes and difficulty in using them, and all that, I'm convinced that I can achieve the same results at less cost and with equal durability and finish with far cheaper and less volatile materials...

BUT, that said, I've never tried the sealer/dope methods either, so I admit that other folks see the benefit of it...

I personally have never seen the need. My results are good enough, especially for LPR. HPR, the other stuff might be called for. I dunno-- no interest in HPR.

Later! OL JR :)

[ghrocketman]

Using Balsa Fillercoat and Sanding Sealer has the CORRECT, nostalgic, YE OLDE aroma for building VINTAGE designs.
It has the added benefit that it does not turn the shop into a friggin dust bowl everytime you get a piece of sandpaper within a yard of touching balsa coated with it, unlike Fill-n'-Finish that immediately generates an atom-bomb's worth of dust the second you touch it with any sanding material.
I have less use for ANY water-based finishing material than I have for taking a hot brandin' iron to a dodge-bawl match.

[Mark II]

When I opened a bottle of Aerogloss dope for the first time after becoming a BAR, I had a Proustian moment (http://www.haverford.edu/psych/ddavis/p109g/proust.html). I was instantly transported back to the basement of my house in Grand Rapids. All of the cares and regrets of my adult life vanished (temporarily). It was late spring, 1967, I was 13 years old, and I was painting my Astron Alpha, my very first model rocket. Ahh, good times, good times....

To me, that's the real deal, the authentic experience.

I too am hesitant about putting anything as watery as thinned Carpenter's Wood Filler onto raw balsa.

A few weeks ago, someone over on TRF started a thread about brushing his balsa fins with Bondo Glazing and Spot Putty. He used acetone to thin it to brushable consistency. I didn't follow the entire thread but apparently he obtained good results with this technique. I have not tried this myself yet, so don't interpret my mention of it as a personal endorsement.

[Solomoriah]

Hey, I've been using water-thinned FnF for a long time with good results.

The only warning I can give you is to coat both sides evenly at the same time. The only time I've seen warping is when I've not followed that rule.

[Mark II]

Luke, I started out using simple techniques, too, and I still use them in some builds. I got into using more "exotic" techniques to address certain specific issues. Eventually I found that some of them were broadly applicable, and so they became part of my regular toolkit of techniques. I previously mentioned using Delta Ceramcoat All-Purpose Sealer (http://www.stuff4painting.com/8-ounces-ceramcoat-prep-all-purpose-sealer-7005-8.html?CAWELAID=600775696&cagpspn=pla&gclid=CO3B1b-LyKcCFQnrKgodPjXyEA). If you really want to keep things simple, just brush three to four coats of this product onto the balsa. Sand between coats. For a silky smooth final surface, gently wet-sand the final coat with 400 or 600 grit aluminum oxide sandpaper (the black kind). The product has no obnoxious fumes and does not irritate or soak readily into skin, so it can be safely used by children. You can buy it at many craft stores, including Michaels, A. C. Moore and Joanne's Fabrics. It is in the tole painting section.

An even better product in my opinion, and probably the best product of its kind, is Pine Pro Sanding Sealer (http://www.hobbylinc.com/htm/ppr/ppr10059.htm). Both products fill the grain and seal the wood at the same time, performing two finishing steps with one product. But Pine Pro does a noticeably better job of it, going on more easily with a paint brush, requiring fewer coats to completely fill the grain, sanding smoother and producing a harder surface. The only problem with it is that it only comes in 2 oz. bottles, which don't last long. I can easily kill from one-half to one entire bottle on the nose cone and fins of a BT-20 or BT-50-sized 3FNC rocket. So you have to keep buying it and buying it. You can get the Delta product in quantities up to 12 oz., which is much handier. I reserve Pine Pro for my high-value clones that I want to exhibit that "catalog pic" look. Wet sanding the final coat also produces a glass-smooth surface, even better than with the Delta product. And just as with the Delta sealer, Pine Pro has no unpleasant fumes, does not irritate skin (as far as I can tell) and can be safely used in classes and by Scout groups. This product can be found in hobby shops; look in the section that has the parts for pinewood derby cars.

Neither product produces a particularly durable or nick-resistant coating on the wood (more important for nose cones than for fins), but what you lose in hardiness you gain in simplicity. And if you are working with kids, these are the products to use. Neither one requires any special technique to apply - just brush the product on in even coats, using a synthetic bristle paint brush (so you don't leave hairs in the coat). Both products clean up easily with water and a little bit of soap. Make sure that you clean your brushes while they are still wet, because once either product dries onto the bristles, you'll never get it out.

[luke strawwalker]

I have less use for ANY water-based finishing material than I have for taking a hot brandin' iron to a dodge-bawl match.

YEE-HAW!!!!! :chuckle: :chuckle:

Or should I say HEE-HAW?? Going kinda redneck on us GH?? LOL:) (ducks and runs)

:chuckle: :chuckle: :chuckle:

Later! OL JR :)

[luke strawwalker]

Luke, I started out using simple techniques, too, and I still use them in some builds. I got into using more "exotic" techniques to address certain specific issues. Eventually I found that some of them were broadly applicable, and so they became part of my regular toolkit of techniques. I previously mentioned using Delta Ceramcoat All-Purpose Sealer (http://www.stuff4painting.com/8-ounces-ceramcoat-prep-all-purpose-sealer-7005-8.html?CAWELAID=600775696&cagpspn=pla&gclid=CO3B1b-LyKcCFQnrKgodPjXyEA). If you really want to keep things simple, just brush three to four coats of this product onto the balsa. Sand between coats. For a silky smooth final surface, gently wet-sand the final coat with 400 or 600 grit aluminum oxide sandpaper (the black kind). The product has no obnoxious fumes and does not irritate or soak readily into skin, so it can be safely used by children. You can buy it at many craft stores, including Michaels, A. C. Moore and Joanne's Fabrics. It is in the tole painting section.

An even better product in my opinion, and probably the best product of its kind, is Pine Pro Sanding Sealer (http://www.hobbylinc.com/htm/ppr/ppr10059.htm). Both products fill the grain and seal the wood at the same time, performing two finishing steps with one product. But Pine Pro does a noticeably better job of it, going on more easily with a paint brush, requiring fewer coats to completely fill the grain, sanding smoother and producing a harder surface. The only problem with it is that it only comes in 2 oz. bottles, which don't last long. I can easily kill from one-half to one entire bottle on the nose cone and fins of a BT-20 or BT-50-sized 3FNC rocket. So you have to keep buying it and buying it. You can get the Delta product in quantities up to 12 oz., which is much handier. I reserve Pine Pro for my high-value clones that I want to exhibit that "catalog pic" look. Wet sanding the final coat also produces a glass-smooth surface, even better than with the Delta product. And just as with the Delta sealer, Pine Pro has no unpleasant fumes, does not irritate skin (as far as I can tell) and can be safely used in classes and by Scout groups. This product can be found in hobby shops; look in the section that has the parts for pinewood derby cars.

Neither product produces a particularly durable or nick-resistant coating on the wood (more important for nose cones than for fins), but what you lose in hardiness you gain in simplicity. And if you are working with kids, these are the products to use. Neither one requires any special technique to apply - just brush the product on in even coats, using a synthetic bristle paint brush (so you don't leave hairs in the coat). Both products clean up easily with water and a little bit of soap. Make sure that you clean your brushes while they are still wet, because once either product dries onto the bristles, you'll never get it out.

Thanks for the tips... Good stuff!

The one thing I've learned in life is that there is, most of the time, more than one way to skin a cat... What works (best) for one person doesn't necessarily work best for someone else. BUT, we can ALL learn something from each other, and that's the important thing.

I hope neither you nor GH took anything I said as disrespectful. It wasn't intended that way. I was just agreeing with Solomoriah, that the 'water based' methods we've been using work "just as well" as these other methods seem to be working for you guys, and the cost, time, and work seems lower as well. BUT, as GH pointed out, it DOES produce some dust... (not an "atom bomb's worth" though-- I don't have a workshop (I took over the dining room table and do most of my sanding there or in the living room watching TV... the main way to reduce the dust, is DON'T PUT AN INCH THICK LAYER OF FNF ON STUFF-- that way there's not that much to sand off :)

At any rate, to each his own, and let's all have fun and agree to disagree... :)

Respects! OL JR :)

[Solomoriah]

I don't mind the dust, since I can't sand indoors anyway. My daughter is allergic to dust. And yeah, you don't put that much on in the first place, and you don't get that much off when you sand it.

GH just likes to rant... it's part of his charm.

[Mark II]

I hope neither you nor GH took anything I said as disrespectful. It wasn't intended that way.Not at all. The purpose of this thread is to share our different techniques. We all have our own, and most of us have more than one in our bag of tricks. I learn about new approaches to doing things by talking to other builders, so I get as much out of threads like these as the original posters do. When I posted my response to you, it wasn't to criticize but rather to explain. But in addition, you and Solo prompted me to recall the other techniques that I described further on. I hadn't thought to mention them until I read both of your posts.

[Mark II]

BUT, as GH pointed out, it DOES produce some dust... (not an "atom bomb's worth" though-- I don't have a workshop (I took over the dining room table and do most of my sanding there or in the living room watching TV... the main way to reduce the dust, is DON'T PUT AN INCH THICK LAYER OF FNF ON STUFF-- that way there's not that much to sand off :)

At any rate, to each his own, and let's all have fun and agree to disagree... :)

Respects! OL JR :)Oh see, I DO know what he's talking about there. I try to be careful about how much filler I put on because I'm mindful of how much I'll have to sand off later, but still I wind up with a good layer of dust over myself and everything else in the vicinity by the time I'm done sanding. I get it regardless of whether I use Carpenter's Wood Filler or Bondo Glazing and Spot Putty or Aeropoxy Light Filler. That's why I prefer to go outdoors to sand down filler - I don't have to clean up the immediate surroundings afterward. I think I mentioned that I do like to use dope filler and sanding sealer on small balsa parts, particularly fins, but that gets to be too expensive once the parts get bigger. Using the other fillers is much less expensive for large areas, so I put up with the dust. And besides, I use CWF and Bondo putty far more often to fill in tube spirals than for anything else, and dope-based products just won't work in that situation.

[ghrocketman]

No offense taken whatsoever.
By the way, "bondo" spot and glazing putty is sort of "dope based" as the same thinners (Toluene and Acetone) for dopes are the solvent base for that putty.
One can make a very good brushable balsa fillercoat by thinning one part bondo putty to four parts dope thinner. It will however produce almost as much dust as water-base F-n-F.

[luke strawwalker]

No offense taken whatsoever.
By the way, "bondo" spot and glazing putty is sort of "dope based" as the same thinners (Toluene and Acetone) for dopes are the solvent base for that putty.
One can make a very good brushable balsa fillercoat by thinning one part bondo putty to four parts dope thinner. It will however produce almost as much dust as water-base F-n-F.

Yes, that's true... but nothing I've found fills a tube spiral as good as Bondo Spot Putty... I've heard folks use FNF for that, and I've tried, but it seems that as soon as I sand the stuff off, it ALL seems to be gone, and the tube spiral is just as much there as when I started. I even tried two applications one time and STILL had spiral left, so I just went back to the BSP... one app, sand, done.

I usually just wipe/daub the stuff on with a bare finger (probably not the brightest idea, but oh well, SOMETHING's gonna kill me sooner or later anyway) and it's quick and easy. Only downside is you get the "funky pink finger" LOL:)

later! OL JR :)

[Mark II]

Yes, that's true... but nothing I've found fills a tube spiral as good as Bondo Spot Putty... I've heard folks use FNF for that, and I've tried, but it seems that as soon as I sand the stuff off, it ALL seems to be gone, and the tube spiral is just as much there as when I started. I even tried two applications one time and STILL had spiral left, so I just went back to the BSP... one app, sand, done.

I usually just wipe/daub the stuff on with a bare finger (probably not the brightest idea, but oh well, SOMETHING's gonna kill me sooner or later anyway) and it's quick and easy. Only downside is you get the "funky pink finger" LOL:)

later! OL JR :)I put on a glove. Now if only I would remember to put on a dust mask when I'm sanding. I'm not sure why you got those results with CWF; it works for me. Bondo putty turns the entire tube pink (due to dust adhesion) but that doesn't cause any problems. I will say that spirals filled with Bondo putty really stand out after sanding, because the putty remaining in them is a dark red. With CWF, they can be hard to see because the filler is a very light yellow in color. I have had great results with both, and I've also gotten less than complete filling in spots with both products. They are very different products but they produce essentially the same results, at least for the applications that I use them.

[luke strawwalker]

I put on a glove. Now if only I would remember to put on a dust mask when I'm sanding. I'm not sure why you got those results with CWF; it works for me. Bondo putty turns the entire tube pink (due to dust adhesion) but that doesn't cause any problems. I will say that spirals filled with Bondo putty really stand out after sanding, because the putty remaining in them is a dark red. With CWF, they can be hard to see because the filler is a very light yellow in color. I have had great results with both, and I've also gotten less than complete filling in spots with both products. They are very different products but they produce essentially the same results, at least for the applications that I use them.

How does the CWF work for you on tube spirals?? I've had dismal luck with it... I've tried brushing on the thinned CWF that I use on nosecones and stuff, about the consistency of hot dog mustard, and I've tried daubing the stuff straight out of the can into the spiral, putting on a thick coat in a bead, etc... It can look good when you start, but as soon as I get the stuff sanded off down to the tube surface, the stuff in the spiral seems to be gone as well and the spiral looks just as present as it was when I started.

Now, the Bondo Spot Putty, I can daub that on over the spiral, let it dry, sand it down, and get a distinctive red line where the spiral was, true enough, but the thing is actually filled in... if you lightly run a fingernail down the length of the tube, it will hang on the CWF "filled" spiral, but won't on the BSP filled spiral-- so the material is still there, obviously. I'm wondering if the adhesion of the CWF is just too low for this application, and it all "turns loose" during sanding and "goes away", where the BSP does not-- it's strong enough in adherence to 'stay put' in the spiral and get sanded down flush with the surface of the glassine tube coating. That's my theory anyway...

I don't always fill the spiral-- kinda depends on the tube, and how noticeable it is, and just "how good" of a finish I want for the rocket. Sport fliers aren't as critical as say semi-scale models, obviously... :)

Just wondering... OL JR :)

[hcmbanjo]

I'm going to have to try the Bondo Spot Putty. I'm always looking for the next best thing.
One thing I didn't notice in the responses - are some modeler's using too rough a sandpaper to sand down CWF in body tube seams? 400 grit is my choice for this.

For filling body tube seams, my end results have gotten better lately using a technique suggested by Bradycros on TRF.

After adding some CWF fin fillets he would cover the fillet area with CA.
This would "lock" the CWF down with less chance of it cracking and "flaking" out.

I agree with most here, I use very little CWF on the body tube seams, meaning I don't paint over the entire body tube.
I'll sand over the dried seam CWF not quite down to the surface. Picture the CWF in the seams as a capital "T" with a flattened (sanded down) top.
I'll then apply CA using a Q-Tip down the seam spiral top of the "T".
This CA cover will help lock the CWF in the seam. The CWF is water based and porous, the CA will penetrate it and into the body tube.

Then sand the top of the "T" down level with the body tube.

This has pretty much eliminated the CWF being sanded and knocked out of the seams.

Did you ever notice how well CWF stays in the seams when smoothing out a launch lug?

[luke strawwalker]

I'm going to have to try the Bondo Spot Putty. I'm always looking for the next best thing.
One thing I didn't notice in the responses - are some modeler's using too rough a sandpaper to sand down CWF in body tube seams? 400 grit is my choice for this.

For filling body tube seams, my end results have gotten better lately using a technique suggested by Bradycros on TRF.

After adding some CWF fin fillets he would cover the fillet area with CA.
This would "lock" the CWF down with less chance of it cracking and "flaking" out.

I agree with most here, I use very little CWF on the body tube seams, meaning I don't paint over the entire body tube.
I'll sand over the dried seam CWF not quite down to the surface. Picture the CWF in the seams as a capital "T" with a flattened (sanded down) top.
I'll then apply CA using a Q-Tip down the seam spiral top of the "T".
This CA cover will help lock the CWF in the seam. The CWF is water based and porous, the CA will penetrate it and into the body tube.

Then sand the top of the "T" down level with the body tube.

This has pretty much eliminated the CWF being sanded and knocked out of the seams.

Did you ever notice how well CWF stays in the seams when smoothing out a launch lug?

I use either 220 or 400 grit to sand the spirals... don't recall which ATM...

Later! OL JR :)

[jetlag]

Hans,

CWF for fillets adds very little for strength, which is what I always thought the purpose of fillets was...Strength.
I don't go to TRF, so I have not read over that particular thread; if aesthetics are your only concern, then by all means keep making fillets with CWF. However, if strength is what you are after, that is the wrong stuff.
I use epoxy, which some here think is overkill. That's OK, too! :) At least I never have fins that flatten out with heat. Ever.

Allen

[jeffyjeep]

Same here. I use epoxy------ONLY. I'd rather have overkill than underkill (or whatever the opposite is of overkill................................................................overreanimate? overletlive?)

[hcmbanjo]

Sorry, I should have been more specific.
On LPR rockets: After gluing the fins in place, I use white glue for fillets.
I've used CWF afterwards and over white glue fillets when I wanted to build up the fillet area. CWF by itself would be too weak for a fillet.
I'm not suggesting it alone for a fin fillet.

I have used epoxy fillets on larger models.

[Solomoriah]

I almost never use epoxy on fins... but then, I have a fully upright storage arrangement, so I've never had a problem with sagging fins. I did use epoxy fillets on my BT-70 3x18 Ultimatum but I didn't on my 4x18 Big Daddy. But then, the Big Daddy is through-the-wall, and sagging seems vanishingly unlikely for it.

I do sometimes use FnF/CWF after filleting with glue, mainly to fill in any bubbles or dings that may remain. Generally only when I've hand-cut the fins.

[jetlag]

If you used epoxy in the first place, you'd never have to go back over the white glue to fill air bubbles. Why make a one step job two? The weight increase is minimal compared to the increase in overall strength.
Epoxy makes beautiful fillets and cleans up with a little alcohol. I never use a glove!

Allen

[Solomoriah]

I'm not making a one step job into two; I always use FnF on my fins anyway, so running my finger down the fillet is hardly another step.

On the other hand, using epoxy fillets adds a step... mixing up the epoxy. Just about the only thing I regularly use epoxy for is engine mount insertion, and that's not about strength, it's about saving my failing sanity. If I have epoxy left from doing that, I might make fillets with it. That's why I didn't say I never do that, but rather that I rarely do.

[ghrocketman]

+1 to what jetlag just said.
I have turned to epoxy for 100% of construction if the rocket will EVER see an engine with the maximum thrust of a single composite E15 or higher. Notice I did NOT say E9; I don't think an E9 could shred a 79 cent Guillow's Sleek Streek glider from 1974.

As long as you are aware that F-n-F fillets are good for nothing but cosmetics.
Epoxy fillets require zero sanding after application and add SIGNIFICANT strength.
I have been accused of building flying tanks, but rarely have rockets busticated due to hangar rash, shreds, or even bouncing off PAVEMENT on recovery.
Yeah, I give up a few feet in altitude, but I think the durability more than makes up for it.

I like to think one of my rockets would survive the "durability test" featured in the Jetson's "Molecular Motors" episode.

"Wait til I take it out of NEUTRAL !"

[jeffyjeep]

Well, I just got my hoard of Aerogloss sanding sealer from AC Supply today (only ONE broken jar this time). I also ordered a few jars of balsa fillercoat, but I was sent balsa fillercoat primer instead.

It seems awfully thin. Is it the same?

[Mark II]

I'm going to have to try the Bondo Spot Putty. I'm always looking for the next best thing.
One thing I didn't notice in the responses - are some modeler's using too rough a sandpaper to sand down CWF in body tube seams? 400 grit is my choice for this.I start off with 220 grit and finish with 320 grit. I also use sanding sponges. I use 400 grit sandpaper to smooth out the top coat of paint and for wet-sanding. It is much too fine of a grit to be useful for actually shaping or reducing something.

As for Luke's question, Elmer's Carpenter's Wood Filler (CWF, formerly known as Fill 'n Finish) works fine for me for filling tube spirals, as I explained in a previous post. I use it and Bondo putty interchangeably, but I generally use CWF for smaller tubes and finer work. I don't use either one on nose cones or fins except to repair holes or gouges that are too small for Aeropoxy filler. I happen to think that CWF works great for filling in tube spirals; that's the primary way I use it and I have no complaints about it. So does Bondo putty, in general. The only thing that I have noticed with the putty is that sometimes I have to reapply it a second time after sanding to get some portions of spirals completely filled. I never have to do that with wood filler.

I don't know about putting CA onto wood filler after applying it the spirals. Frankly, the thought of it makes me cringe. First of all, if the filler is applied correctly, nothing more needs to be added to it. Secondly I try to do as little damage to the tube as possible. Putting a hard, gritty crust on top of the filler prior to sanding it down is asking for trouble. It requires more vigorous sanding to get it off, which greatly increases the likelihood that you'll scuff up the tube pretty badly. Putting CA onto the wood filler is a solution to a problem that never seems to arise for me, and crude one at that. Seriously, CWF doesn't need any augmentation; it always works great for me when it is properly thinned, correctly applied and allowed to dry thoroughly (around here, that requires 24 hours, usually). The reason that I like to use Bondo Glazing and Spot Putty is because I can apply it straight from the tube with my fingertip. But looking at it strictly from a performance standpoint, it offers no advantages over Elmer's wood filler, and it also sometimes utterly fails after application. More on that in another post.

I fill the spirals on my tubes first, prior to any assembly. It's much easier to do and can be done more completely that way, because there isn't anything in the way. Since sanding down whatever filler I use lightly scuffs up the surface of the tube, the process also does an excellent job of preparing the tube for gluing. Most of the time I spray the tube first with a light coat of primer before I apply the filler to the spirals. This seems to "harden" the tube a little bit and helps to protect it from becoming severely abraded when I subsequently sand down the filler. After it has completely dried (usually overnight) I sand off nearly all of the primer before proceeding to fill the spirals.

I also begin filling and sealing balsa nose cones and fins early on in the build process too. If I don't paper them, I fill and seal the fins with (usually) dope filler and sealer after I cut them out but before I bond them to the rocket. (I do mostly scratch-building, hence I cut nearly all of my fins myself. When I started out in rocketry, tracing fin outlines onto stock with a template and then cutting them out was a normal and universal part of kit-building.) I cover the fin root area with a little strip of masking tape, and I give the bonding surface a couple of quick licks with sandpaper right before I apply the adhesive, so this practice doesn't compromise the bonding to the tube. Unless it has a complicated form with hard-to-mask surfaces, I hold off on actually painting the rocket until after it is built.

[Mark II]

Hans,

CWF for fillets adds very little for strength, which is what I always thought the purpose of fillets was...Strength.
I don't go to TRF, so I have not read over that particular thread; if aesthetics are your only concern, then by all means keep making fillets with CWF. However, if strength is what you are after, that is the wrong stuff.
I use epoxy, which some here think is overkill. That's OK, too! :) At least I never have fins that flatten out with heat. Ever.

AllenI sometimes use wood filler or Bondo putty as a last step to smooth out any imperfections in the fillet after I have done as much as I can to sand them out. I make fillets out of (usually) epoxy, so that takes care of the strength issue. Usually the epoxy forms a perfect and smooth fillet, but occasionally the surface of it needs a little bit more work. The filler is added later to correct minor cosmetic imperfections, and it never serves as a significant component in the fillet.

Although I usually only use scant amounts of it, on a few recent occasions I have had to apply comparatively thick layers of Bondo putty to fix strnf but not particularly well-formed fillets (on rockets that I built awhile ago, that I'm only now getting around to painting). This is where I have had it fail on me. Specifically, after having applied generous amounts of putty to the fillets and then letting it get completely dry, I have gone back to sand the putty smooth, only to find that the layer is no longer solid all the way through, but has become hollow. Somehow the putty just below the surface has dissolved, dissipated or drastically shrunk. This happened more than once, on more than one rocket. I firmly pressed the putty in when I apply it, specifically to push out any air bubbles and then firmly smoothed it down with my finger several times afterward, so I'm pretty confident that the problem wasn't caused by trapped air bubbles. And when I went to sand it after allowing it to dry, the putty always looked like it was still firmly adhered to the surface and did not appear to have pulled away from it anywhere. It was as if the inner half of the layer had just disappeared.

I still haven't figured out what caused this. At first I tried to fill in the hollows with more putty, but after it had dried, they reappeared when I began to sand the areas. The only way that I was finally able to correct the problem was to completely sand out all of the original putty and to start over.

[Mark II]

I mostly use epoxy for fin fillets in order to add strength and also because it is easy to work with. I also use it at times when the strength it adds isn't really necessary, simply because it makes glass-smooth fillets. But jetlag, please do wear a nitrile glove when you smooth the epoxy with your finger. Your skin may not react to it at first, but give it time. Plus, if you are using alcohol with it (a very good technique) but aren't wearing a glove, the alcohol readily absorbs into your skin, bringing a bit of the epoxy in with it. You really don't want epoxy to get through your skin and into your system, but that's what you're doing when you don't wear a glove. Latex gloves don't provide an effective barrier. Thick vinyl gloves will work, but they don't fit well enough to be useful in this technique. A better choice is nitrile gloves. The material is an effective barrier, and the gloves have the fit that you need.

Where I live, fins are never at risk from sagging due to high ambient temperatures, but even so, I rarely use white glue for fillets anymore, except for micro rockets. Yellow carpenter's glue makes for very strong, but also hideously ugly, fillets. Nevertheless, one alternative to using epoxy for fillets in small model rockets is to use wood glue, and then cover the ugliness up and smooth things out later with filler. Just a suggestion.

[foamy]

I'm working on a rocket that has very small, almost unnoticeable seams in their unpainted state. Is it worth while to go to the trouble of trying to fill them? I was considering letting them go and hoping a primer and base coat would sorta fill 'em in. Is this wishful thinking on my part?

[Doug Sams]

I'm working on a rocket that has very small, almost unnoticeable seams in their unpainted state. Is it worth while to go to the trouble of trying to fill them? I was considering letting them go and hoping a primer and base coat would sorta fill 'em in. Is this wishful thinking on my part?My filling methods have evolved to applying primer before filling the spiral. In many cases, after a couple coats of primer, no filler is needed.

I should point out that I use CWF, which is compatible with primers under it. Some fillers, such as spot putty, may cut the primer and cause it to lift. So YMMV.

Doug

.

[scigs30]

I Have Quarts and Pints of original Pactra Aero Gloss Balsa Fillercoat and Sanding Sealer from the 70's, 80's and 90's that I have stockpiled from old hobby shop closeouts in person and on ebay.

Other than from Sig or Brodak, Pints/Quarts have not been available since the early 90's (at least for Aero Gloss).
Brodak's dope is actually re-packaged Full-Scale Aircraft Randolph Dope. It is available in 3 times the colors that the Aero Gloss line was in it's highest point and is every bit as good.

Brodak's Sanding Sealer is almost exactly the same as the Aero Gloss product; the Sig stuff is usable, but only if you cut it about 60/40 Sealer to thinner; otherwise the Sig is far too thick and will form hideous outgassing bubbles.

As far as Balsa Fillercoat goes, I think the only source now is in small (3.5oz largest) bottles from Midwest under the Aero Gloss label. Fortunately, making your own Balsa Fillercoat is a snap. Take a pint or half-pint of Clear BUTYRATE (NOT Nitrate) Dope in a brand of your choice and dissolve a couple tablespoons plain unscented Talcum Powder and a teaspoon of "Plastic Wood" into a half-pint or double those amounts of solids into a pint of Clear dope. That IS Balsa Fillercoat.
I thought Brodak stopped selling their Sanding Sealer........MMMM I love the smell of Aerogloss Balsa Sealer in the morning.

[sandman]

I know a lot of you guys have trouble with it but I use straight undiluted Elmer's white glue brushed right onto the fins but...after they are attached.

Let it dry overnight and a quick sanding with 220 and it's ready for primer.

I've been doing it that way for over 40 years. Never a problem.

[captain26]

Thanks to eveyone for all the great info on filling/finishing balsa. There certainly are many different approaches to the final finish. I'm getting pretty good results with the fill/finish but intend to try a couple of other methods for comparison.

Another question I have concerning final finish. How does one get uniformly rounded leading edges on fins? Presently, I'm using a sanding bar and eyeball? Again, as a kid I didn't devote much time to the problem. Glue'em on, paint and fly!

[jeffyjeep]

400 grit sandpaper, my right thumb, and eyes. :)

[stefanj]

How I handle rounded / tapered edges:

Need a sanding block with fine sandpaper (or starting with coarse for very hard balsa or basswood), a small piece of fine paper, and depending on the size of the fin a large piece of fine. And a small piece of extra fine.

First, run the sanding block along each angle of the edge of the fin you want to round. Hold the block at a 45 degree angle. Use the same number of strokes. You want to end up with the angles lopped off, creating two more angles:

From this:
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To this

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Then, lay the balsa almost flat on the paper, gripping it so the edge being rounded is away from you. Draw it toward you and raise up the edge you're holding. Eventually the fin will be straight up. Repeat on the other side. Alternate sides until the angle is turned into a nice symmetrical curve. It will still be a little rough. I call this step "stropping."

Then, curl a piece of paper over the edge. Run it along the edge to further round and smooth the curve. Repeat with extra fine.

You can do something similar for tapered edges, but the initial angles you cut are far shallower and the "stopping" involves more pulling at the shallow angles and smoothing just a very small curved edge to the taper.

[Mark II]

I do essentially the same thing as Stefan, except that I do it all with the sanding block, and I use 320 grit sandpaper throughout. I hold the fin in such a way that I can sight down the edge. I run the sanding block in long, gentle strokes in one direction only down the entire length of the edge so that I can closely monitor my progress. Sanding rounded edges takes patience, finesse and a good eye, but it's not difficult to do. I work on one side of each edge at a time. I get that one rounded, then turn the fin around and do the other half.

The goal is to sand the sides of the edge round without taking anything off of the edge itself. Both laser-cut fins and fins that I cut out myself are trimmed to the exact size that they should be, so sanding the edge itself would reduce the width or otherwise change the shape and make the fins non-conforming and non-identical. Prior to rounding the edges (or sanding in airfoils) I stack-sand all of the fins together to get them to be identical in size on all sides, and then when I'm rounding the edges I endeavor to maintain the sameness. I pay particular attention to keeping the fin shape's corners sharp and well-defined. I stop frequently and check each fin against the others to make sure that they all still match, and I compare the rounded/airfoiled edges of all of them to see that the rounding is symmetrical and identical on all of them.

There were a couple of tricks that I used when I first decided to get serious about doing the edges right, and sometimes I still use one or both of them. One is to mark each edge (except the root) with a thin pencil line to divide it in half. I lay the fin down next to a piece of basswood that is half the thickness and draw the line down the edge with a sharp pencil. This reference line helps me to insure that the two sides of each edge are symmetrical. The other trick is to draw a similar line on each side of the fin, parallel to each edge, that is one-half the fin thickness inside of the edge. Then I place a strip of not-too-tacky masking tape along the line on the side away from the edge. This acts as a guard to prevent me from over-sanding the edge. Together these two tricks help to get the two rounded halves of each edge to be symmetrical. Often now, because of the practice, I can get them to be even and symmetrical by just eyeballing it, but I still use these tricks from time to time. I use a combination of drawn lines and tape guards, too, every time I sand in airfoils, but for them the arrangement is a little bit more complex.

Keep in mind these two adages: less is more, and moderation in all things. Do just enough sanding and remove only enough material to get the job done. Do less sanding that you think the edges will need, and stop before you think that you are done. And also always stroke the sanding block down the entire edge each time. Avoid sanding only a section of the edge, because you run a great risk of sanding in a "saddle" - a dip in the fin's outline, if you do. Also, of course, always do this sanding and shaping before you attach the fins to the rocket. It is nearly impossible to do the job well and to get all of the fins to be identical after they have been attached. You absolutely must use a sanding block or angle for this in order to apply even pressure for the entire length of each stroke.

[RocketBoy 32]

This may sound crude to some of you guys. Oh well.
I first harden the balsa nosecone with thin CA glue. This step
always takes place outside and with the wind at my back.
After the CA cures, I sand the nosecone with medium and then
fine sandpaper. Next I put on a pair of rubber gloves and put the
nosecone shoulder into a scrap body tube. I spray the cone with
Rustoleum Grey auto body primer and put it on a little thick.
After the cone is sprayed completely, the primer will be thick
and wet. I take my gloved finger and rub the sandable primer
into the grain of the balsa nosecone until it's smooth and all
filled in. After the primer dries (1-2 days) I sand the cone again
with medium fine and finish grade sandpaper. One more shot of
primer and after that's dry the cone is all ready for a base coat
of airbrushed enamel or acrylic.

[ghrocketman]

Brodak still has Sanding Sealer; they have it at Prop Shop Hobbies which is only about 4 miles from where I work.
They discontinued Balsa Fillercoat, but that is no big deal as you can make your own with Clear Dope that one dissolves plain Talcum powder into.

[jeffyjeep]

Is that in Centerline, MI?

[Doug Sams]

Guys,

When I read some of these finishing techniques, I can't decide if they're penance or self abuse. In a couple cases, I thought the subject was Mein Kampf instead of Finishing Balsa ;)

Doug

.

[sandman]

Is that in Centerline, MI?


YEP! it is!

[jeffyjeep]

I LOVE that store! I need to get a job over that way again. I haven't been over there in about 5 years when I did job at BAE Metals in Centerline. (or was it Warren?)

[Bill]

When I read some of these finishing techniques, I can't decide if they're penance or self abuse. In a couple cases, I thought the subject was Mein Kampf instead of Finishing Balsa ;)



As long as they do not send the storm troopers to force me to do it their way...


Bill

[Solomoriah]

Last spring Justin and Jaclyn were doing the finishing work on their rockets for 4-H. I don't know how many passes Justin did, priming and sanding, but at one point I looked at it for him. It had only the faintest traces of spiral visible, and the fins were nearly perfect. I said, "You can probably call that good and start painting it."

He said, "You wouldn't," and proceeded to prime it one more time for good measure.

Here it is:
http://rocketry.gonnerman.org/images/2010-fair-bomb.jpg

[ghrocketman]

Centerline, Mi is a city that is completely within the city limits of Warren, Mi. which surrounds it. Not sure if the address is which for the Prop Shop, but it is one or the other.
Great olde-tyme hobby shop like Rider's of Flint and Joe's Farmington used to be.
Since Rider's moved to their new location about 15 years or so ago it has turned into little more than an overpriced glorified toy store with a hobby section.

[luke strawwalker]

I sometimes use wood filler or Bondo putty as a last step to smooth out any imperfections in the fillet after I have done as much as I can to sand them out. I make fillets out of (usually) epoxy, so that takes care of the strength issue. Usually the epoxy forms a perfect and smooth fillet, but occasionally the surface of it needs a little bit more work. The filler is added later to correct minor cosmetic imperfections, and it never serves as a significant component in the fillet.

Although I usually only use scant amounts of it, on a few recent occasions I have had to apply comparatively thick layers of Bondo putty to fix strnf but not particularly well-formed fillets (on rockets that I built awhile ago, that I'm only now getting around to painting). This is where I have had it fail on me. Specifically, after having applied generous amounts of putty to the fillets and then letting it get completely dry, I have gone back to sand the putty smooth, only to find that the layer is no longer solid all the way through, but has become hollow. Somehow the putty just below the surface has dissolved, dissipated or drastically shrunk. This happened more than once, on more than one rocket. I firmly pressed the putty in when I apply it, specifically to push out any air bubbles and then firmly smoothed it down with my finger several times afterward, so I'm pretty confident that the problem wasn't caused by trapped air bubbles. And when I went to sand it after allowing it to dry, the putty always looked like it was still firmly adhered to the surface and did not appear to have pulled away from it anywhere. It was as if the inner half of the layer had just disappeared.

I still haven't figured out what caused this. At first I tried to fill in the hollows with more putty, but after it had dried, they reappeared when I began to sand the areas. The only way that I was finally able to correct the problem was to completely sand out all of the original putty and to start over.

Yeah, the BSP is meant to go on in thin layers, not like a bead of material... it shrinks a LOT trying to use it in a 'bead' of material.

I think that the problem is the lacquer thinner used as the solvent for it... but's that's just my guess... LOL:) The extremely small particle size probably has a lot to do with it too...

Later! OL JR :)

[dyaugo]

Here's my method that I have been using since 1977 (almost 35 years):

Phase 1)
3 coats of WELL-MIXED and STIRRED Aero Gloss Balsa Fillercoat with sanding between coats 2 and 3; coat two should be applied over coat one as soon as the solvents flash in coat one.
Sand coat two after an hour and apply coat 3.
After drying at least an hour, sand coat 3.

Phase 2)
After the sanded balsa fillercoat has dried overnight, apply two or more coats of Aero Gloss Sanding Sealer over the fillercoat, with sanding between coats after they dry.

Some apply the sealer before the fillercoat but that is BACKWARDS as the fillercoat FILLS much better over the raw wood.

Finished wood parts using this method can be topcoated with ANYTHING including butyrate dope. Using Elmers Water-based fill-n-finish results in a substrate NOT compatible with dope or "hot" solvent content lacquers. In addition, fill-n-finish makes a HIDEOUS DUST MESS when sanding which Aero Gloss products do not.

Sounds like you have it perfected. What do you mean when the solvents "flash"

[Captain Ron]

Guys,

When I read some of these finishing techniques, I can't decide if they're penance or self abuse. In a couple cases, I thought the subject was Mein Kampf instead of Finishing Balsa ;)

Doug

.

I hear what your saying.... :chuckle:
having built models since 1977 I have to say that my building techniques have improved over the years. But I've always kept it simple.

To each his own I guess but for me I just smear on with my finger some Elmer's Carpenter's wood filler over the balsa nose cones and transitions, and for the fins I use a single edged razor blade, let dry, then sand down until im satisfied, prime, paint fly...

Heres a pic of an example, both nose and transition that make up the payload area of the rocket are balsa done this way.

[dyaugo]

I skimmed through this thread and it's pretty amazing at the different techniques that everyone has for filling balsa. I don't think there's any right or wrong way to do this, but everyone has something to offer. I think certain applications call for certain procedures depending on the kit or scratch build you are working on. Here are some pictures of my X-15. I used FnF throughout the build. On the balsa and spirals. I agree that when applying the FnF to the balsa to do both sides, but what I do is I apply it with a brush, but then I take plastic putty knife and remove 90% of it until it has an even coat. The same thing you would do with the glue when skinning the fins. After it dries completely I lightly sand it with either 320 or 400 depending on the surface and then repeat. When I am happy with the results I prime with Duplicolor (red) and that is the "tell all" after the primer if there are any imperfections I repeat the process again until there aren't any imperfections, but I only stayed focused on the areas that need to be filled...not the whole fin and when I primer I just primer that area only, not the whole model. Then I paint the topcoat "wet" it on and then let it dry....

There's a lot involved, but I feel that if you want a good looking model you are going to have to take the time and do it right....

[Raygun]

Sounds like you have it perfected. What do you mean when the solvents "flash"


Just that they have oxygenated and evaporated or burned away in the air. You'll know it when you see it after coating a few times with experience using it :) .

[dyaugo]

Just that they have oxygenated and evaporated or burned away in the air. You'll know it when you see it after a few times :) .

OK I understand now...more or less it doesn't look wet anymore

[Raygun]

I skimmed through this thread and it's pretty amazing at the different techniques that everyone has for filling balsa. I don't think there's any right or wrong way to do this, but everyone has something to offer. I think certain applications call for certain procedures depending on the kit or scratch build you are working on. Here are some pictures of my X-15. I used FnF throughout the build. On the balsa and spirals. I agree that when applying the FnF to the balsa to do both sides, but what I do is I apply it with a brush, but then I take plastic putty knife and remove 90% of it until it has an even coat. The same thing you would do with the glue when skinning the fins. After it dries completely I lightly sand it with either 320 or 400 depending on the surface and then repeat. When I am happy with the results I prime with Duplicolor (red) and that is the "tell all" after the primer if there are any imperfections I repeat the process again until there aren't any imperfections, but I only stayed focused on the areas that need to be filled...not the whole fin and when I primer I just primer that area only, not the whole model. Then I paint the topcoat "wet" it on and then let it dry....

There's a lot involved, but I feel that if you want a good looking model you are going to have to take the time and do it right....

It's a fine rocket you have there. One of my all-time favorite subjects. I always enjoy seeing many design interpretations. To to add to you astute analysis of methodology when it comes to rocket construction, I would like to add ( for the benefit of others), though we all demonstrate some craft in picking a technique that works well for each of us, it is up to the individual to try for themselves and not rely too much on what is said on these forums and take the comments for face value only. Never take someones word as virtuous. It's your prerogative try something new for yourself and see how it works for you. The doing and experimenting and also building on what others have experienced is the fun part!
Cheers! :)

[dyaugo]

It's a fine rocket you have there. One of my all-time favorite subjects. I always enjoy seeing many design interpretations. To to add to you astute analysis of methodology when it comes to rocket construction. I would like to add that, though we all demonstrate some craft in picking a technique that works well for each of us, it is up to the individual to try for themselves and not rely too much on what is said on these forums and take the comments for face value only. Never take someones word as virtuous. It's your prerogative try something new for yourself and see how it works for you. The doing and experimenting and also building on what others have experienced is the fun part!
Cheers! :)

Thanks for the compliment...

Well said. I couldn't agree with you more. This is exactly why I save my scrap balsa to experiment on it before applying the technique to an actual kit. When you get right down to it there could a be a few variations of the same technique(s) ...like you said it's up to the individual to try this their-self. :)

[Raygun]

OK I understand now...more or less it doesn't look wet anymore

There, you said it better than me! ;)

[dyaugo]

It's a fine rocket you have there. One of my all-time favorite subjects. I always enjoy seeing many design interpretations. To to add to you astute analysis of methodology when it comes to rocket construction, I would like to add ( for the benefit of others), though we all demonstrate some craft in picking a technique that works well for each of us, it is up to the individual to try for themselves and not rely too much on what is said on these forums and take the comments for face value only. Never take someones word as virtuous. It's your prerogative try something new for yourself and see how it works for you. The doing and experimenting and also building on what others have experienced is the fun part!
Cheers! :)

BTW - The X-15 is fitted to take an "E" engine....haven't launched it yet. Waiting on the weather to clear and winds to calm down. I'll be using a 6 foot 1/4" rod.

[dyaugo]

I used regular wood sealers in the past on balsa ; "Last & Last" ,Minwax, Varnises and Poly sealers... thats what Dad had around the house. Some took along time to dry and some not so long. But they did SEAL very well. I agree with your info on Water based filler, I got me some Elmers FnF and I have had issues with the cell ends of the NC and edges of fins blistering. I would get a nice wet coat of paint on the NC and would watch as little pin head size blisters would pop out. Only thing I could make of it is a dif in temp when painting. I been takeing the parts out on to my sun-porch that may be only 40-50 deg ,shooting them, let set some and takem back in house. I guess its "gas/air" coming out on the balsa cell ends.I know if I had used a TRUE WOOD sealer this would not happen.Anywhoo-I ve had it with the mess and softness of the FnFs. Im going to get me some Aero Gloss Products. I have used Aero Gloss Products in the past. I built alot of balsa/tissue paper airplanes. Mostly rubber band man powered. Hm, I might just pick me up a simple airplane kit when Im at the LHS getting the Aero Gloss.

I just ordered the Estes Eagle F-15. I'm going to use the dope method on it, because I feel it would allow me better access to tight areas with less fuss. Right now I cut a scrap fin from a piece of balsa that I am experimenting on...I'll post some pictures once I'm done and if I like the results.

I never had any problems with FnF. I always mixed it so it's like peanut butter and evened it out with a plastic putty knife and sanded it lightly with 400. Repeat and sand as necessary.

I also used copy paper to skin skin the fins with much success. No issues at all and very quick and clean.

I feel that the reason people have issues with using any method is they go overkill. FnF is mixed too thin and too much water. Or skinning the fins they use too much glue which contributes to warping the fins.

Each scratch build or kit that you decide on building you are faced with obstacles when finishing. I mean you wouldn't try to skin the fins on a kit like the F-15, because it's too intricate, but it would be easy to skin fins on a regular 3-4 fin rocket where it's easy to work the paper and cut out...

That's why I believe that you should be proficient at all the techniques, because each methods offer something the others don't...just an extra tool in your tool belt...ya know?

[dyaugo]

Brodak still has Sanding Sealer; they have it at Prop Shop Hobbies which is only about 4 miles from where I work.
They discontinued Balsa Fillercoat, but that is no big deal as you can make your own with Clear Dope that one dissolves plain Talcum powder into.

I just bought some Balsa Fillercoat Primer...isn't it the same thing?

http://www.brshobbies.com/catalog.php/BRSHobbies/dt1150/pd33240/Midwest_70_4_Aero_Gloss_Balsa_Fillercoat_Primer__3.5_oz_bottle_ships_ground_

[hcmbanjo]

That's why I believe that you should be proficient at all the techniques, because each methods offer something the others don't...just an extra tool in your tool belt...ya know?

You are right on the money!
Every kit (beyond three fins and a nose cone) will require different techniques.

to Scotty Dog:
Fill N" Finish or Carpenter's Wood Filler is just that - a filler.
Being it's water based, it doesn't seal the balsa.
Glues and even stain will permeate balsa filled with CWF. The filled wood isn't sealed until you shoot the primer.
(Stain will not permeate a dried white glue fillet.)

[dyaugo]

The last couple days I went ahead and tried the Aerogloss "DOPE" method of treating balsa.

I cut a sample fin out of some scrap balsa I had laying around and treated it to two coats of Balsa Fillercoat Primer #70-4. I first sanded the fin with 320 and then 400 to smooth out the surface and remove any imperfections before applying the Balsa Fillercoat. I then sanded the second coat with 320 and applied a third. I allowed it to dry over night and came back in the morning sanded again using 400 this time. After I sanded the third coat I started to apply the Sanding Sealer #71-4 I applied three coats and sanded in between each coat after they had dried for 2-3 hrs. I started with 320 and work my down to 600 on the last coat. (320 1st, 400 2nd, 600 3rd)

I applied a few coats of Duplicolor HBP and the primer showed no imperfections...

I was really happy with the results and the process. I feel pretty comfortable using this method and depending on the type of kit and conditions I would use this method. I am going to be building the ESTES Screaming Eagle kit and I plan on using this method.

If I was building your standard 3 fin rocket I would skin the fins. Quick and easy and you can't argue about how strong it makes the fins.

If the rocket was large scale and big pieces of balsa and there were no small intricate parts I would probably go with the FnF or maybe skin some of the parts? Cost effective on larger rockets...

Bottom line. Perfect each method and you will be more versed in your techniques when prepping your model for primer and paint. :)

[Raygun]

The last couple days I went ahead and tried the Aerogloss "DOPE" method of treating balsa.

I cut a sample fin out of some scrap balsa I had laying around and treated it to two coats of Balsa Fillercoat Primer #70-4. I first sanded the fin with 320 and then 400 to smooth out the surface and remove any imperfections before applying the Balsa Fillercoat. I then sanded the second coat with 320 and applied a third. I allowed it to dry over night and came back in the morning sanded again using 400 this time. After I sanded the third coat I started to apply the Sanding Sealer #71-4 I applied three coats and sanded in between each coat after they had dried for 2-3 hrs. I started with 320 and work my down to 600 on the last coat. (320 1st, 400 2nd, 600 3rd)

I applied a few coats of Duplicolor HBP and the primer showed no imperfections...

I was really happy with the results and the process. I feel pretty comfortable using this method and depending on the type of kit and conditions I would use this method. I am going to be building the ESTES Screaming Eagle kit and I plan on using this method.

If I was building your standard 3 fin rocket I would skin the fins. Quick and easy and you can't argue about how strong it makes the fins.

If the rocket was large scale and big pieces of balsa and there were no small intricate parts I would probably go with the FnF or maybe skin some of the parts? Cost effective on larger rockets...

Bottom line. Perfect each method and you will be more versed in your techniques when prepping your model for primer and paint. :)

Good observations.
I also want to add that one has to realize the Aerogloss Dope is fuel proof coating,thus the price tag for the formula. One has to ask themselves can i achieve the same finish after the paint is on, for the price in your range of project scope. Just one more added dimension to the matrix of possiblities... For myself, I live in Boston where i have to live without hobby shops that carry anything of specialty. Shipping costs being what they are, and the excellent product the FnF is for the scope of work i am involved, I never needed Dope. I used to use it a lot when i lived back home in Miami, 20 years ago when fuel was cheaper and 911 didn't happen yet, and hobby shops were everywhere. (Yikes--How naive we all were then). Getting back into the hobby, I cant say enough of FnF, with how much respect I have for Dope. It is safer, cheaper and I can get mirror finish after a base coat color ( white sand-able) primer. And it is surprisingly light; I would say equal to dope. So ask myself, do I need fuel proofing that is reserved for RC gas powered planes?
B/G rockets are a perfect example where dope would be ideal, No primer or even pigment would be needed just clear/ balsa filler or colored dope, so as to forgo primer base-coat, to keep the craft light.

[ghrocketman]

One of the largest reasons I still prefer Aero Gloss over any of the FnF water-based stuff is the mess factor.
I can sand dope-based fillers with a minimum of dust created.
Using FnF causes a massive amount of dust anytime I get a piece of sandpaper within a foot of the stuff.
I can sand Aero Gloss finished parts in my living room while watching TV. FnF strictly outside or in a shop.

[dyaugo]

One of the largest reasons I still prefer Aero Gloss over any of the FnF water-based stuff is the mess factor.
I can sand dope-based fillers with a minimum of dust created.
Using FnF causes a massive amount of dust anytime I get a piece of sandpaper within a foot of the stuff.
I can sand Aero Gloss finished parts in my living room while watching TV. FnF strictly outside or in a shop.

Absolutely less dust and mess. There's pros and cons to each method.

[Raygun]

One of the largest reasons I still prefer Aero Gloss over any of the FnF water-based stuff is the mess factor.
I can sand dope-based fillers with a minimum of dust created.
Using FnF causes a massive amount of dust anytime I get a piece of sandpaper within a foot of the stuff.
I can sand Aero Gloss finished parts in my living room while watching TV. FnF strictly outside or in a shop.


I know what you mean. The first few times i notice this ' mess' factor but I worked out a simple system for myself so now its not a problem anymore. I simple use a sanding block of my preferred choice and sand the fins on each side flat on newspaper ( I use shopping circulars-- it might be the sheen of this type of newsprint that does it)
I sand and the stuff does not proliferate but settles directly around the fins. The fine powder does not stick to the newsprint and i proceed to fold and funnel into a rubbish bin next to me, the newsprint and powder react like teflon because there is no residue on the newspaper afterward, weird really. I repeat the process for each side of each fin. I use a brush to wisk off the fins--their is a little mess their but i do that part at the end briefly outside my kitchen door. I work in my living room, for its non toxic nature and I have no other place really in winter, and I no longer have dust problems as a bonus. That might make me a 'neat and tidy' individual, but hey, it works for me. I take each product for what it is, and see what I can do. I don't have bias for water or solvent base either way. They all have their pros and cons though solvents have serious cons if not handled safely. I still recommend masks for particulates, and nitril gloves and chemical masks for ketones. Their known to be a cause of cancer. Hey, who really can afford health problems?

[ghrocketman]

Are you filling/sanding the fins before gluing to the tube ???
If so, you do realize the glue fillets are bonding to the sealer with much less strength than to the actual fin material being filleted and soaked with the glue into the grain, correct ?

[Raygun]

Are you filling/sanding the fins before gluing to the tube ???
If so, you do realize the glue fillets are bonding to the sealer with much less strength than to the actual fin material being filleted and soaked with the glue into the grain, correct ?


Oh yes, learned that trick, wow, seems like forever ago. YEs i do sand and finish before gluing. I leave a bit of margin free of finish for filleting. I still do it to this day, regardless of new materials and formulas. Old good habits. I guess i do take the time to be detail oriented. I do no know if anyone does this too- I just never ask. After filleting, whatever grain might show through is sandable primer out. I am big on sanding to level out grain. I have has some very awesome Astron Sprints that demonstrate the blemish free joints without hint of grain. I realize not everyone is like this and, well I have shortcomings of my own in other areas of building. Paper transitions is still needs to be improved but i learned a lot there too. I just see other folks execute it flawlessly.

[scigs30]

On simple builds I will build the rocket then apply my sealer and sand smooth. On more complicated designs I will seal the wood prior to gluing the wood to the rocket. It would be a major PITA to try and brush on sealer and sand it smooth with the rocket already built. I do have all kinds of sanding sticks, but still it would be tough. I have never, never , ever had a fin come off doing it this way. I still have to sand the tough areas after the primer is applied, but I am only sanding once, not over and over.