Primer instead of sanding sealer, what kind of primer?
 

I'm getting back into building rockets after probably at least 20 years since my last one. (Still got several I build over 20 years ago though!)

I notice the instructions are saying to use primer instead of sanding sealer. I've done several searches both here and general Google about this with pros and cons both ways.

Anyway, that's not really my question. I haven't been able to find anything to specifically answer my question..

My question is really, is there any special kind of primer I should use? Is there a modeler's primer? Or just any regular Krylon or Rust-o-leum primer from the hardware store?

Thanks!

Some builders choose to use a high fill auto primer to completely fill the grain. Others use Elmer's Carpenter wood filler thinned with water to fill the grain, others use the old fashioned sanding sealer, and others paper the fins.

And some of us just want to fly and don't really care about spirals or grain.

I fill grain the old fashioned way-the best way-with good old fashioned DOPE.
3-4 coats of Aero Gloss Balsa Fillercoat with sanding between coats 2/3/4.
I apply the first two coats 'wet' right over the top of each other; both sides of one fin then move to next fin until they have the initial two coats. Wait 2 hours or more, then sand, apply coat 3, wait 2 hours or more then sand and decide if a 4th coat is needed. Let final coat dry overnight, sand then apply two coats of Aero Gloss Sanding Sealer with sanding between coats.
This is time consuming but you get Balsa fins/cones/transitions with a completely filled smooth surface that is top-coat ready for your choice of color finish.
I usually use vintage Aero Gloss colored Dope as the color topcoat from a spray gun as I have a vintage stock of quarts, pints, and half-pints of all the Pactra colors that rivals most 80's hobby shops.
If using basswood for fin stock ONE coat of Balsa Fillercoat followed by one coat of Sanding Sealer is usually plenty.
Finishing with Dope is time consuming, but ALWAYS rivals all other finishing systems other than extremely costly Automotive Urethane (with catalyst/hardener) finishing systems.
If you can find old stock of two-part Petit Hobby-Poxy or K&B Super Poxy topcoat, that also rivals Dope.

Thanks for all the feedback, but most of it is really overkill for me. I'd really like to get back to the original basic question.

Yes, back when I built rockets regularly as a kid, I finished all balsa parts using coats of Aerogloss, sanding between coats. That's what I expected to keep doing when I recently started building again, so I was a bit surprised when the instructions in the kits I bought recently said to use primer paint instead of aerogloss. So I thought I'd give the primer a try.

I'm not a perfectionist by any means. I'm not going to put the time and effort in that some have described using various suggested methods. For me, I'm either sticking with the aerogloss, or going to try just regular spray in a can primer.

So going back to the original question, if I want to do the primer, can I just use regular Krylon or Rust-o-leum primer in a spray can, or is there is a specific modeler primer paint I should look for? I looked on the Testors paint rack at the hobby shop and didn't see a primer. The instructions don't give any detail about any specific primer.

Actually, now that I think about it more, even beyond the primer, what about just the regular spray paint? I've always used Testors paint. Is there a reason to prefer this vs. just regular Krylon or Rust-o-leum spray paint? I'm sure it's cheaper (probably the same price for 2 or 3 times the size of spray can)? Certain colors I'm guessing I can probably really only find in the model spray paint, but for basic black, white, red, blue, green, would just Krylon or Rust-o-leum do fine?

Thanks again!

Well I don't know about do fine. some will swear by one or other, but yes, Krylon and Rustoleum work to very well. Rustoleum filler primer works all right for covering and being sandable.

One thing is for sure, ask ten YORF'ers and you'll get eleven answers about what is best. :chuckle:

and btw, don't limit yourself to spray primers, I've had good luck with Rustoleum painter's touch Ultra Cover in the quart can. It just needs to be thinned a touch.

clhug,

You can buy cheap primer that does a respectable job of filling grain on balsa, and seams on body tubes. While I like filler/primers like Duplicolor, I've had good results using Walmart brand cheap primer, called HomeShades. It's about $1.33 a can last time I bought it. Dries pretty quickly, and sands easily. If you cannot find this one, try Rustoleum Filler/Primer, which works well, it just costs a bit more. Some cheap primers do not sand well, and gum up your sandpaper., so you may have to experiment if you must buy an unknown brand.

Spray it on pretty heavy, and do maybe 3 coats to have a heavy build. If you get a run here and there, no worries, since you need to sand most of it off! The key is to leave primer in the balsa grain and body seams, and not have a thick primer coating on the entire surface. If you do this the grain and seams will never disappear, you'll just see less distinct impressions. Don't sand too deeply though, or you'll tear up the balsa or the cardboard. When you start to see traces of balsa and cardboard peeking thru the primer, you are getting close to the point where you should stop, and prime again. You may have to do this prime/sand cycle several times, depending on the depth of grain and seams. You final cost can be lighter than fill coats, such that you have a uniformly colored, smooth surface for your color topcoats.

Get a primer that is compatible with your finish coats. Usually I get the primer made by the same company as the paint. Look for "sandable" or "high fill" primers.

kj

Welcome back to the hobby !




No. BUT... as you can tell from the responses, alot of people like filler or high-build primer, especially if you forego sanding sealer or some other filler on the wood parts.



Not that I know of.



That'll work. Two popular cans are:

As you say, Testors in those little (3 oz. ?) hobby shop cans is the expensive way to go. I only go there if I need a particular color that I can't get in the bigger and more economically priced cans.

FWIW I've been using Rusto Painters Touch 2x from the Depot and Wally World. I've been seeing alot of the Krylon ColorMaster line at the Walmarts around me as well so I intend to try that sometime soon.

Hope this helps.

You may consider investing in an airbrush, especially if you want to paint low power rockets. There is a variety of colors available to spray more so than the few colors you may find at the hardware store and a lot cheaper than Testors or Tamiya model spray paints.

There IS a 'modeler's' primer; just what I spoke of- Aero Gloss Balsa Fillercoat and Sanding Sealer.

It certainly is a safe practice to use the same brands, but I've never had compatibility problems between primers and subsequent top coats. I've sprayed almost every imaginable brand of enamels, and several types of lacquers, over the three primers I listed earlier.

BUT ... make sure the primer coat is dry. I wait at least 24 hours after primer coats, and longer if I can still detect an odor, meaning it is still outgassing solvents.

Thanks again everyone!

I stopped at Home Depot on the way home from work tonight and found the Rust-oleum Painters Touch 2X Ultra Cover primer so I bought the flat white. I'll give that a try.

Thanks also for the info about regular paint.

I'd give the Painters Touch paint a try, too. I really like the way they go on, much better than Rustoleum spray paints from years ago. I'm not a huge fan of the new Krylons, maybe because the old Interior/Exterior type from about 10 years so was so good, and then it got replaced with the inferior (IMHO) Indoor/Outdoor type.

The Walmart "Color Place" red and grey primers do an excellent job for me, and they're 99 cents a can...

Otherwise, I use the Rustoleum high fill autobody wet sandable primer... good stuff!

later! OL J R :)

Two more follow-up questions.

For primer, does it matter whether to use flat or glossy primer? I was thinking flat would sand better, but maybe it doesn't make a difference? Any other reason to use flat vs. glossy primer? Flat primer won't interfere with using glossy top coat, or vice versa, will it?

I also see people mention, and the primer I bought says, wet/dry sandable. What exactly does wet sandable mean? Does that mean able to be sanded before the paint itself dries, or that it can be sanded with a bit of water after the primer dries? Either way, why would one do wet sanding?

Thanks again!

All primers have a flat finish which helps the top coat to adhere better. Wet sanding is done when the primer is completely dry, wet the sand paper in some water (not too wet) and sand, The water helps the sand paper not become too clogged with sanding dust. You don't have to wet sand. Most modelers find what works for them. I usually dry sand, using finer grits to get a smooth finish.

As to the flat/glossy question-- I don't have any experience there, but I don't really think it should matter much... that said, I'd stick to flat. Flat SHOULD have a higher solids (and probably slightly larger particles) count and therefore cover up and fill in stuff better. Just stay away from the stupid "paint and primer in one" materials... Those are just counter to everything that needs to be done to get a good finish-- they're a "one step" product for lazy guys, IMHO... the whole purpose of priming is filling in minor imperfections and the surface being sanded down smooth PRIOR to paint... How do you sand the primer if it's IN the paint?? Plus, you can't put a heavy load of primer solids in the paint without compromising the color and consistency and applicability of the paint, yet the flowability of the paint is hampered by the solids of the primer anyway... Yechh-- what a mess... stuff can't do EITHER job right IMHO...

No, the finish of the primer has no effect on the final "finish" of the paint (meaning whether it's glossy or flat finish paint). The primer's job is to transfer as much "solids" (particles in a solvent) to the surface being finished as possible, to flow out and fill as many imperfections as possible, to promote adhesion between itself and the surface being finished, and promote adhesion of the paint layer going over it to itself and the surface, and to be sandable enough to allow the surface blemishes to be sanded smooth to hide their presence. Paint, OTOH, is simply pigments in a solvent designed to provide color. PAINT DOES NOT HIDE FLAWS, IT MAGNIFIES THEM!!! Whatever your surface looks like when you're done priming and sanding, is about what it'll look like when it's painted; if you can see imperfections in your primer coat after sanding, you WILL see them after painting. Many people mistakenly believe that paint will hide imperfections, that even if they can see imperfections after priming and sanding that they'll somehow 'disappear' when the paint is applied, that "the paint will cover it up". This isn't true. BASICALLY, THE APPEARANCE OF THE FINAL FINISH IS HOW IT LOOKS BEFORE THE PAINT IS APPLIED... IOW, if you can see imperfections, flaws, etc in the sanded primer BEFORE you paint, you will almost certainly see them AFTER painting.

"Wet sandable" primer is designed to be sanded using water. "Dry sandable" primer is not designed for this. "Wet sanding" is a process used to make professional-grade finishes on things like show cars and stuff like that, where you want that "wet look" or "mile deep" paint job... Typically it's done by using a garden hose just dribbling water on the surface being sanded while the surface is sanded with a fine-grade sandpaper using a long sanding bar to get the surface COMPLETELY SMOOTH and level and even. The purpose of the water is to cool and lubricate the sandpaper and to flush away sanded off particles to prevent these very-fine-grit sandpapers from clogging up with particles. Dry sanding liberates a lot of particles in the form of sanding dust... wet sanding takes those particles away in water. Sanding also creates heat via friction, and can make the primer sticky and gummy, gumming up your sandpaper and clogging it with particles, making it worthless. Wet sanding can carry this heat away, prevent the gumminess, and flush the particles from the paper preventing clogging of the paper.

Now, obviously using true "wet sanding" principles with a dribbling garden hose water source isn't practical for most model rocketry applications (particularly paper tubes and wood fins, although fiberglass and other waterproof materials certainly CAN be wet-sanded) due to the nature of the materials (paper tubing and wood fins/cones). BUT, we can use a variation of the method that produces near FLAWLESS results... I call it "damp sanding". I start by hardening my balsa cones and transitions with ultra-thin CA glue wicked into the surface... take it outside (so the fumes don't run you out of the house) and wet the surface of the cone/transition with ultra-thin CA glue, which will wick itself down into the wood grain of the balsa like a sponge soaking up water. There it will cure and "harden" the balsa, much like fiberglass impregnated with resin. This helps toughen the cone so it's not AS prone to damage (as an unhardened one). Doesn't make it "bulletproof" but it DOES help... Sand down the "grit" and "fuzz" raised by the CA with 220 grit paper, then I brush on a layer of Elmer's Carpenter's Wood Filler thinned down to about the consistency of hot dog mustard with a few drops of water worked into a dab of it in a small disposable bowl with the brush. Let this dry a couple hours, then sand it down with 220 grit paper followed by 400 grit paper to fill and eliminate the wood grain and large surface imperfections. Then I give it 2-3 progressively heavier coats of primer, allow to dry fully (overnight is best, longer depending on your climatic conditions at the time, but I HAVE sanded within just a few hours on occasion...) Sand with 220 grit paper followed by 400 grit paper, dry. Carefully inspect the surface, looking for any major imperfections such as low spots, waviness, high spots where the primer was sanded through to the bare surface, etc. If necessary, reapply more primer and allow to dry and sand again... though usually this isn't necessary if you'd done things right up to this point. Sometimes just hit a light coat of primer on any 'high spots' where the primer sanded through. Now, you're ready to either 1) call it good and paint or 2) damp sand.

To be continued...

OL J R :)

Continued...

If you want a TERRIFIC finish, you'll probably want to damp sand. I start by getting a roughly 2x4 inch piece of 400 grit wet/dry sandpaper, a small (disposable or non-eating-out-of-it-from-now-on) bowl of water, an old towel, and a couple paper towels. To damp sand, dip the paper into the water, then shake off the excess water or daub it on the towel so the sandpaper is very damp but not dripping wet. Then sand the surface in SMALL OVERLAPPING CIRCLES, while simultaneously ROTATING THE PART IN YOUR HAND. DO NOT sand in straight lines back and forth, or sand in the same spot continuously... ALWAYS keep the sandpaper moving, and rotate the part so that you're not sanding in one spot, which creates flat spots. DO NOT put too much pressure on the paper-- let the grit of the paper do the work, slowly grinding off the surface of the primer or material. (By the way, these are the sanding motions and principles you should use on ANY sanding, wet, damp, or dry, shaping balsa or doing fine finishing work). As you damp sand, you will notice the particles coming off the surface will combine with the moisture in the paper and start to form a thickening "sanding mud" on the surface of the part and the paper... as you continue to sand off more particles, this will get thicker and thicker. After a couple minutes, dunk the paper in the bowl of water, and rub your thumb or fingers over the surface of the grit-- this will dislodge the trapped particles and wash them away. If you want to inspect the surface, gently wipe away the sanding mud with a damp paper towel, and then dry the surface with the dry clean paper towel... or you can continue damp sanding until the entire surface has been damp sanded and then clean and inspect. Just keep repeating the process working your way up the cone, rocket, whatever until you get to the end. Clean it off with a damp paper towel to remove all the "sanding mud" and then dry the slightly damp surface off with a dry, clean paper towel. Inspect the surface by holding it up between your eye and a distant light source-- a brightly lit window, lamp, chandelier, etc... Look at the "glint" of reflected light on the surface of the tube or cone, and inspect how that glint looks... if you can see waviness, pits or imperfections or low spots, nibs or hard particles or high spots, and SANDING SCRATCHES, they will ALL be visible in this glint of reflected light. You probably won't be able to feel them or see them looking at them directly, but the reflected light acts just like a laser reading the tiny hills and valleys in a CD or DVD, showing things you cannot see directly. If the reflected glint is perfectly smooth, the surface is done. If you can live with any imperfections you see, you're done. Allow the parts to dry for an hour and you're ready to paint.

You CAN still ruin the surface at this point by misapplying the paint... paint in thin, quickly and evenly applied coats to prevent the dreaded drips, runs, and sags. Avoid "dry spray" and "orange peel" through proper distance of the spray from the surface (not too far away) and runs and sags by not getting too close to the surface or spraying too heavy a coat. If you apply the paint properly, there is NO need for any 'color sanding' of the final paint coat-- it should flow out evenly and smoothly on the surface without any flaws or blemishes at all... and you'll have a GORGEOUS finish...

I paper my fins with printer paper and white glue, and most rocket tubes are glassine, so even fins and tubes can be "damp sanded" for great results... the key is to remember your DAMP sanding, not WET sanding... the only moisture should be on the paper and the very surface of the primer being sanded... there SHOULD NOT ever be water "dripping" off the rocket. Wipe off the surface with a damp paper towel periodically if you're worried about moisture buildup (and to get rid of the 'sanding mud' before it dries out and is hard to remove). The sanding mud actually helps the sanding, BTW, because it "polishes" the surface as you sand-- you can actually get a mirror finish in primer using damp sanding if you try! Of course you don't really WANT it THAT finely polished, as you want SOME "tooth" for the paint to grip the surface of the primer, meaning it should be slightly dull... Don't sand with too much pressure to avoid sanding scratches, which are hard to remove and will show through paint. Sanding in a small overlapping circular motion and keeping the parts your sanding moving (or move around on the surface constantly) and avoiding "straight back and forth" sanding motions (to the extent possible-- sometimes you "have to" up against fin roots/fillets and launch lugs and stuff) will give the best results, regardless of damp or dry sanding. How far you take it and how good you want the appearance is up to you... you can quit at "looks good from 15 feet away" or you can put a museum-quality finish on a rocket if you desire, I've done it, so can you if you want...

I've got some build threads and incorporate papering fin tutorials and hardening balsa tutorials, and primering, sanding, and damp sanding tutorials in them... look for the "Dr. Zooch beta-build" threads I've done... If you want links lemme know and I'll look them up...

Later and good luck! OL J R :)

Second this opionon. I use it alot cheap and drys fast.
But still cant beat the end result of filler coat and sanding sealer dope.

When I use primer for filling balsa and priming tubes, I use either Duplicolor, or 3M/Bondo light gray primer. Both are lacquer based, dry very quickly, and sand great. I've found Rustoleum clogs sandpaper more quickly, so only use it when I need a white primer. I can still get Aerogloss Sanding Sealer from my LHS, but only use it on small models.

Is that the Clean Metal Primer? Or the Automobile Primer?

The former is oil based and takes a while to cure while the latter is lacquer based and dries very quickly.

From my perspective, the clean metal primer is about the same as flat paint. Anyway, because it takes a while to fully cure, it can be prone to clogging the sandpaper. I've only purchased and used it by accident (ie, due to my own ignorance :) ).

But I've had excellent results with their automotive primers.

Doug...not that I've painted a rocket in forever... :o

.

It used to be called auto primer, now it's called "Gray Filler Primer", #720. It's lacquer based, as it recommends lacquer thinner to clean the nozzle. The stuff dries extremely fast, I can put on multiple costs just holding the rocket for a minute between coats. Can says ready for sanding in 30m, though I usually wait a day, just so I don't bring any stink into the house.

I said to heck with filling and sanding, I paper all my fins now. Fast, smooth and no piles of primer dust.

I've seen other people mention papering fins. Can you explain what that means? I would assume that paper sucks up paint much more so do you still prime before the top coat? But are you saying that you don't have to sand the primer before the top coat?

Thanks!

Personally, I much prefer the finish proper filling, sanding, etc gives to fins. Papering examples I've seen look so-so in this regard. Plus, if the fin is damaged, the repair is more involved, and the resulting finish looks worse. With age papered fins look like, well, papered. By the time one makes a papered fin look as nice as a properly finished fin, about the same level of effort, perhaps more, is needed. It's an alternative, but not a great one IMO.

Allen

On ANY rocket I have seen the "papering" technique used on fins, they always look like substandard RUBBISH.
If you want to be lazy or un-traditional and still have a nice finish, lightly sand the fins then apply iron-on R/C airplane MonoKote or Ultrakote.

I just stick with good old-fashioned Balsa Fillercoat and then Sanding Sealer for prepping ALL wood parts for topcoating. This "Dope" method works the BEST and has an olde-tyme proper nostalgic AROMA.

The only way I've found to make papering look really nice without a lot of work is to use butcher paper, shiny side out. The primer doesn't soak in but doesn't adhere as well, so a very light scuffing is needed. Too much and the primer soaks in, not enough and even moderate stresses can cause primer to delaminate taking the finish coats with it. If primer soaks in, it often ends up bubbling the paper. Sometimes before it's finished, sometimes after the model is complete and in public view.

You still need the magic touch when gluing the paper on. Too wet and it wrinkles the paper. Too dry and it eventually bubbles or pulls away. Five or ten minutes in the sun on the pad and the balsa can outgas enough to create bubbles.

I've also soaked the entire paper fin with thin CA a couple of times. I ended up having to do a considerable amount of filling and sanding to get a nice flat slick finish, to the point that the only advantage was fin strength, not ease of finishing.

*backstroking through the vitriol*
To each there own....

clhug:
Glad you asked. Use typing paper with school glue, glue stick or whatever works for you to cover the woodgrain. Below is a detailed How To posted on TRF. Give it a try and see what you think.
Personally I use self adhesive label paper to avoid wrinkling.

Papering fins thread on TRF

Just a few of my builds with papered fins

I am a yuuuge fan of papering fins. If I didn't have rockets to build I'd probably buy balsa sheets and paper them just for the sheer fun of it (I'm exaggerating, but only a little). Fin papering does not eliminate the need for priming or sanding, it just fills the wood grain very quickly and effectively. When your fins are papered, there's no such thing as discovering you missed a grain or two after you sand the primer. Your fins will be smooth. The paper does not absorb any excessive amount of paint; you just treat it like any other surface on the rocket. Paper gets used elsewhere in builds anyway, no difference here.

Papering also brings the bonus of adding a good amount of strength to balsa fins. You don't always need the extra strength but it can't hurt.

The biggest advantage for me is that I get foolproof results with much less work than anything else I've tried. I even papered a balsa transition, and it worked out great.

I have been successfully papering with self-stick label paper, and have documented my technique and results an endless number of times on TRF (I look forward to one day being the only person ever banned for too much fin papering). The technique is slightly different than the one Layne linked to.

There is a legitimate question about the longevity of the self-stick labels. I do everything I can to ensure that they are permanent, but only some years into the future will I be able to judge.

Here are a few examples (all from TRF), starting with the most recent:
- APRO Lander main fins
- My final current formula
- Papered transition
- More detailed post showing process

Attached are some sample pics, not all of which really show the fins that well, but whatever.

Anyway, use whatever technique works best for you. I enjoy doing it this way, and am happy with the results.

Gary,
You do outstanding work. I'll check the TRF threads to learn of your magical ways.
STill haven't had time to build the new Achilles, maybe after the Christmas rush and getting the Spanish Inquisition released.

I am not Gary... although, I could consider changing my name if sufficiently "motivated" (ahem).

Here's a thread I did years ago detailing the process *I* use, which works wonderfully... Here's the relevant posts...

http://www.oldrocketforum.com/showp...406&postcount=6

http://www.oldrocketforum.com/showp...407&postcount=7

http://www.oldrocketforum.com/showp...408&postcount=8

http://www.oldrocketforum.com/showp...409&postcount=9

Which are part of this thread I did of a build of the Dr. Zooch Vanguard Eagle, here...

http://www.oldrocketforum.com/showthread.php?t=7444


No, papering doesn't "suck up much more paint"; it provides a MUCH simpler and more straightforward (and MUCH STRONGER) way to fill the balsa grain BEFORE giving the rocket the usual priming/sanding/painting treatment. The paper basically laminates the balsa fins, giving them MUCH more strength for very little weight gain, and gives you a nice smooth surface to primer. The rocket it still given about 2-3 coats of a good primer, allowed to dry overnight, and sanded with 220 grit followed by 400 grit, sometimes even "damp sanded" with moistened sandpaper to give the final surface treatment before paint application. I've detailed the process on that in other threads if you're interested...

Papering saves having to put a half-dozen coats of primer or sanding sealer on balsa fins trying to fill in the huge honkin' voids in the grain, and having to sand them all out smooth between coats (well, with primer you CAN spray 2-3 coats, sand it out, and then another 2-3 coats and sand it out again, and get *acceptable* results, but usually a third application/sanding cycle is required to get EXCELLENT results. Papering the fins takes care of the grain, and gives you a fin surface more like the rest of the rocket, so a single priming/sanding cycle is usually enough (sometimes a few 'touch ups' are required as needed, but very few) to produce a terrific surface ready for painting to get a top-notch finish on the rocket.

later! OL J R :)

EXACTLY!!!

Every guy I've seen knock the papering of fins are using SOME OTHER METHOD OR MATERIALS than what Layne is talking about here... I use the EXACT SAME METHOD, and it WORKS, PERIOD!

That said, there are some "tricks" to it, but they're really easy.

First off, USE WHITE GLUE!!! Don't use yellow carpenters glue (shrinks too much) or (IMHO) other types of glue. Layne says he's had good luck with glue sticks and school glue, both variations on the plain old white Elmer's glue... I've had terrific luck with plain Elmer's white and haven't really tried the others, but I wouldn't be surprised that they worked. Yellow glue just doesn't behave the same, it shrinks too much, and causes problem.

SECOND, *THE* biggest problem I've seen is people using TOO MUCH GLUE. Use ONLY enough glue to completely cover the paper in a VERY THIN, EVEN COAT of glue... press the fin down HARD against the paper, then I apply another VERY THIN EVEN COAT of glue to the unpapered surface of the fin, and fold the fin over onto the rest of the paper, over the leading edge. YOU DO NOT WANT TOO MUCH GLUE OR THE PAPER WILL WRINKLE, WEAKEN AND TEAR, WARP THE FIN, ETC. Basically you should be able to wipe your finger across the glue-applied surface and it come away DAMP with glue, but NO EXCESS GLUE... People usually use too much glue in the MISTAKEN BELIEF that additional glue adds strength-- IT DOES NOT!!! Additional glue only WEAKENS the joint and creates problems from the water "solvent" in the white glue softening and distorting the paper.

THIRD, you need to take a round sharpie marker and BURNISH DOWN the paper onto the surface of the paper-encapsulated fin. Work from the leading edge toward the trailing edge of the fin, and from the center towards the root and tip edges of the fin. This squeezes out ALL excess glue and makes the paper settle down into intimate contact with the wood itself, with only the thinnest layer of glue solids between them to form the joint, and ensure that all air bubbles and other nasties are out of there and that the joint is GOOD AND TIGHT! The paper should be burnished over the edges of the fin to ensure that the edges are well sealed down-- in fact I run the sharpie marker around the paper and burnish it down to itself and the edges of the fin, to ensure absolutely good contact and "seal" the fin inside a layer of paper. The paper is then trimmed later with a SHARP X-ACTO blade to remove any paper from the tip and root edges and trim it down flush to the trailing edge of the fin once dried.

FOURTH, by using the "folded over the leading edge" technique (I detail in my Dr. Zooch Vanguard Eagle build thread) the paper is strongest where the aerodynamic loads on it are the strongest-- it's FOLDED OVER THE LEADING EDGE. Other techniques that are commonly used, using profile "cut-outs" of paper to "skin" the fins from BOTH SIDES, leave an exposed edge at the leading edge which the several hundred MPH slipstream of air rushing past the rocket is attempting to RIP OFF of the fin, making for a weak spot. Most of the delamination problems I've read about have come from people using "self-adhesive label paper" and other things with weak adhesives that are NOT THE BEST FOR PAPER AND WOOD BONDING APPLICATIONS and that leave an exposed edge where the slipstream can attack it in flight, and try to overcome this deficiency with CA "superglues" to essentially "nail" the paper down. If the paper is ONE PIECE that wraps OVER THE LEADING EDGE and then encapsulates BOTH SIDES of the fin, the only "seam" in the paper/glue joint is at the TRAILING EDGE, which the slipstream is PUSHING DOWN against the fin... I've NEVER had a white glue papered fin delaminate.

FIFTH, lots of people believe you have to use some "magic paper" or heavy duty cardstock to achieve any results... this is simply NOT TRUE and COUNTERPRODUCTIVE!!! I use ordinary Wal-Mart 60 pound PRINTER PAPER with perfect results. Heavy-weight paper and cardstock is harder to bend and get to stay "stuck down" because it wants to "straighten out" due to it's own thickness-- which is easier to fold and get it to hold a sharp crease?? Typing paper or construction paper or cardstock?? Same thing applies to papering fins! Some folks have, with varying degrees of success, tried various "butcher papers", "Freezer papers", etc. Some have detailed their failures due to these "exotic papers" and then condemn the entire process because of poor material selection. While some have experienced success and advocate for certain procedures and materials, which if it works for them and you can duplicate their results, GOOD FOR THEM AND FOR YOU! If not, *I* CAN report that using THIN LAYERS OF WHITE GLUE, wrapping the paper OVER THE LEADING EDGE TO ENCAPSULATE THE BALSA FIN, and using ORDINARY PRINTER OR TYPING PAPER *WILL* work, IF DONE CORRECTLY. Others have attempted using other papers like "self adhesive label paper" and such things, again, with varying levels of success and various longevity.

Check out the threads and posts I posted... try it AS SHOWN and if you do it RIGHT, it'll work!

Later! OL J R :)

The only method of finishing balsa I take a more "dim view" upon than water-based priming/filling is coating it with paper.
Yechhh.
VOC-laden solvent-based ALL-STEPS finishing of wood or NOTHING for me.
Works the BEST and has the added bonus of PI$$ING-OFF enviro-whacko nut-jobs.

JR,
Points 4 and 5 are very important!
I don't paper all the time but when I do -
Laying the paper over the leading edge is the best way to go! Round just the leading edge, don't round the outside and trailing edges. You end up with a easy rounded leading edge that has no chance of peeling off.
The outside and trailing edges remain square. The paper is easy to trim off and that remaining square sides are easier to fill.
I have better luck using a glue stick. For smaller fins, the glue stick is not as wet and a pretty good working time before it sets up. On larger fins I's probably go with the white glue.

Self adhesive label paper does lift. I remember my old Gyroc hinges coming up.

60 lb. weight paper is great for papering. 110 lb. card stock is too heavy. You don't want to add weight to the back of the model.

Thanks for all the info!

:eek:
What have you done with Gary?!