Ye Olde Rocket Forum

Go Back   Ye Olde Rocket Forum > Work Bench > Building Techniques
User Name
Password
Auctions Register FAQ Members List Calendar Today's Posts Search Mark Forums Read


Reply
 
Thread Tools Search this Thread Display Modes
  #1  
Old 08-25-2011, 01:15 PM
scigs30 scigs30 is offline
Master Modeler
 
Join Date: Jul 2006
Posts: 2,261
Default Primer, the Cure All for sealing balsa?

Here is a link to my latest build using primer only to seal the balsa.
http://forums.rocketshoppe.com/showthread.php?t=9815

When it is all said and done, I cannot believe the results I received without using balsa sealer. I have used Balsa Sealer and filler ever since I started building rockets to seal and fill the balsa. For the most part I have had great success, but that is because after the balsa sealer is dried and sanded I spray 2 to 3 coats of primer with more sanding for a smooth finish. Now in the beginning all the rocket directions and rocket books mention using balsa filler or sealer then spraying the rocket with Enamel top coats. Never in the literature did it say anything about using primer after the sealer and before the top coats so that is what I used to do.....For the most part the rocket would come looking ok but obviously without primer some imperfections would show. Also the balsa fins would be smooth but some grain would show unless I used 7 to 8 coats. Now that everyone is using primers, you can see by itself it works great as a filler and does not add much weight as long as you sand most of it off and I think most of us do that anyway. The biggest advantage I see with the primer only is that you only sand twice vs 4 to 8 times as with sealers and primers together. I sprayed 3 coats of primer with no sanding in between coats and let it dry for one day. The next day I sanded it smooth and added 2 more coats. Now I think the only thing I might do different is after sanding the first time I would look to see if I have any major imperfections and correct with putty or wood filler, on this build there were no issues. After filling the major imperfections I would only sand the filler and begin spraying my next 2 to 3 coats of primer. I have seen others on these forums use primers only and also the new Estes directions now mention to use primers to fill the balsa so why would we still use fillers or sealers? I have only built one rocket with this method so I have not made up my mind if I am going to do this with all my builds but I will post my results and like to hear what others think.
Reply With Quote
  #2  
Old 08-25-2011, 01:22 PM
Leo's Avatar
Leo Leo is offline
German Model Rocket Builder
 
Join Date: Sep 2005
Location: Germany
Posts: 1,313
Default

Quote:
Originally Posted by scigs30
...
I have seen others on these forums use primers only and also the new Estes directions now mention to use primers to fill the balsa so why would we still use fillers or sealers?
...


Because we are old school model builders. Yes sir
__________________
Leo

My rocket fleet and more @ Leo's Leisure Site and on YouTube - My latest project: ALTDuino
Reply With Quote
  #3  
Old 08-25-2011, 01:37 PM
DaveR's Avatar
DaveR DaveR is offline
Master Modeler
 
Join Date: Apr 2006
Location: North MS
Posts: 836
Default

I have pretty much always used primer. I've used balsa sealer a few times and for your afore mentioned reasons, I've all but abandoned the practice. I get great results with just using primer. I use primarily gray for starters usually 2 coats (then sand) and then another coat (more sanding). I'll shoot a last coat of white (with a final sand) if the rocket is not going to be white in it's final color. I do sand the balsa sheets several times using different grits before removing/cutting the fins, which kinda helps to lessen the grain somewhat.
I occasionally fill spirals with Fill and Finish (or whatever it's called today) but the sprials have to be "big". FNF generates way too much dust for my likes.

Occasionally there's a grain or two that peeks through, but I'm good with that. After a flight or two there's usually going to be couple of dings anyway. OTH, with your showroom finishes that may not be acceptable to you.

I guess everyone is different and it boils down to how much time you want to spend sealing, priming, and sanding. It is supposed to be a hobby.
__________________
Dave
Fire is the leading cause of fire.
Was once SAM#0132
Reply With Quote
  #4  
Old 08-25-2011, 01:40 PM
scigs30 scigs30 is offline
Master Modeler
 
Join Date: Jul 2006
Posts: 2,261
Default

I agree with that Leo, but like I said I didn't start priming rockets until I came back into the hobby 6 years ago. Before that it was sealer and top coat and that would be true old school. Part of me would miss good ole Aerogloss so I am thinking about still using it on my vintage builds and using primer on my new models.
Reply With Quote
  #5  
Old 08-25-2011, 02:10 PM
ghrocketman's Avatar
ghrocketman ghrocketman is offline
President, MAYHEM AGITATORS, Inc.
 
Join Date: Jul 2005
Location: Nunya Bizznuss, Michigan
Posts: 13,443
Default

Balsa Fillercoat and Sanding Sealer "toughen" the balsa; the fillercoat fills and penetrates making the balsa "denser" which prevents easy denting, and the Sanding Sealer gives a tough "plastic like" top coat further toughening the balsa.
Primers do virtually nothing to toughen balsa.
For Basswood or ply, primer is actually plenty.
Not so for balsa unless you want easy dentability.
__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL
, if you have to ask what is "NORMAL" , you probably aren't !

Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !
Reply With Quote
  #6  
Old 08-25-2011, 02:37 PM
scigs30 scigs30 is offline
Master Modeler
 
Join Date: Jul 2006
Posts: 2,261
Default

I was thinking that but then remembered that when applying filler or sealer we sand it back down to the balsa so there is not top coat. What makes it seem stronger is the fact that the grain is filled and that is also done with primer. I used test pieces of balsa and there was no difference in strength or dentability....if that is a word....nope it is not a word.
Reply With Quote
  #7  
Old 08-25-2011, 02:51 PM
ghrocketman's Avatar
ghrocketman ghrocketman is offline
President, MAYHEM AGITATORS, Inc.
 
Join Date: Jul 2005
Location: Nunya Bizznuss, Michigan
Posts: 13,443
Default

I'm thinking you are sanding the filler and sealer far too deep.
__________________
When in doubt, WHACK the GAS and DITCH the brake !!!

Yes, there is such a thing as NORMAL
, if you have to ask what is "NORMAL" , you probably aren't !

Failure may not be an OPTION, but it is ALWAYS a POSSIBILITY.
ALL systems are GO for MAYHEM, CHAOS, and HAVOC !
Reply With Quote
  #8  
Old 08-25-2011, 03:53 PM
AcroRay's Avatar
AcroRay AcroRay is offline
Craftsman
 
Join Date: Sep 2010
Location: South-Western Pennsylvania
Posts: 265
Default

I've been using Rustoleum "High Build" automotive primer since my second BAR build, and the results have been fantastic even with only the most minimal treatment with Elmer's FnF underneath.

I do notice that it tends to add a little more weight to the bird.
Attached Thumbnails
Click image for larger version

Name:  Primer Coat.JPG
Views: 155
Size:  409.4 KB  
__________________
BAR after a 29 year absence. Using my plastic, resin & vinyl kit building skills (and my paycheck)
to build what I could only dream of as an 11 year old...


My Rocketreviews.com Gallery
Reply With Quote
  #9  
Old 08-25-2011, 04:11 PM
chrism chrism is offline
Master Modeler
 
Join Date: May 2008
Location: Greenville, PA
Posts: 1,291
Default

Quote:
Originally Posted by scigs30
Here is a link to my latest build using primer only to seal the balsa.
http://forums.rocketshoppe.com/showthread.php?t=9815

When it is all said and done, I cannot believe the results I received without using balsa sealer. I have used Balsa Sealer and filler ever since I started building rockets to seal and fill the balsa. For the most part I have had great success, but that is because after the balsa sealer is dried and sanded I spray 2 to 3 coats of primer with more sanding for a smooth finish. Now in the beginning all the rocket directions and rocket books mention using balsa filler or sealer then spraying the rocket with Enamel top coats. Never in the literature did it say anything about using primer after the sealer and before the top coats so that is what I used to do.....For the most part the rocket would come looking ok but obviously without primer some imperfections would show. Also the balsa fins would be smooth but some grain would show unless I used 7 to 8 coats. Now that everyone is using primers, you can see by itself it works great as a filler and does not add much weight as long as you sand most of it off and I think most of us do that anyway. The biggest advantage I see with the primer only is that you only sand twice vs 4 to 8 times as with sealers and primers together. I sprayed 3 coats of primer with no sanding in between coats and let it dry for one day. The next day I sanded it smooth and added 2 more coats. Now I think the only thing I might do different is after sanding the first time I would look to see if I have any major imperfections and correct with putty or wood filler, on this build there were no issues. After filling the major imperfections I would only sand the filler and begin spraying my next 2 to 3 coats of primer. I have seen others on these forums use primers only and also the new Estes directions now mention to use primers to fill the balsa so why would we still use fillers or sealers? I have only built one rocket with this method so I have not made up my mind if I am going to do this with all my builds but I will post my results and like to hear what others think.



I just built Sunward's Explorer, and the instructions do not mention using a sanding sealer on the balsa at all, just primer. This was surprising to me. I don't ever remember any instuctions that do not mention using sealer.
Reply With Quote
  #10  
Old 08-25-2011, 09:56 PM
Mark II's Avatar
Mark II Mark II is offline
Forest Sprite
 
Join Date: Dec 2006
Location: Back Up in the Woods
Posts: 3,657
Default

I only use primer on wood as a paint base for the topcoat. I do all of my sealing and grain filling with other products. I have tried many different techniques and this works the best for me. On tubes I use a light coat of primer as a base before I fill spirals because it helps to prevent scuffing when I sand down the spiral filler. Once all of the surfaces are smooth, I hit the entire model with one coat of primer. I very lightly sand that coat and after toweling off the dust I proceed with top coats. I try to limit my use of spray primer and paint because of the cost. Aside from spraying a thin coat onto paper tubes prior to filling, I only use primer for its main purpose, which is to help the paint adhere to the surface. Using it for such things as sealing and filling wood grain and filling tube spirals quickly becomes expensive. I have tried using it for those other tasks, and I was appalled at how quickly I ran through cans of it.

I am not disputing your conclusions about the technique, but for me it is just not economical to do it that way.
__________________
Mark S. Kulka NAR #86134 L1,_ASTRE #471_Adirondack Mountains, NY
Opinions Unfettered by Logic • Advice Unsullied by Erudition • Rocketry Without Pity
+09281962-TAK-08272007+
SAM # 0011
Reply With Quote
Reply


Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump



All times are GMT -5. The time now is 03:14 PM.


Powered by: vBulletin Version 3.0.7
Copyright ©2000 - 2024, Jelsoft Enterprises Ltd.
Ye Olde Rocket Shoppe © 1998-2024