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Building Tips and technical articles. => Paint and finishing => Topic started by: Brian Massey on March 09, 2011, 02:47:51 PM
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I've always used what I think of as "regular" butyrate, that is the tautening variety. But I got to thinking, is that a waste when doing the bare wood? Is there any advantage or disadvantage to using non-taut on the wood, then tautening only on the open bays to shrink the silk?
Any thoughts/advise is appreciated.
Brian
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Brian,
I use the full strength stuff only over open bays and only one coat at that. Everything else gets non-taunting. I also find that things stay in better alignment that way. The full strength taunting stuff can pull pretty hard.
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Brian, I've started using sanding sealer only on the bare wood, lots of thin coats. Even use it to stick the tissue on now. It doesn't shrink I know that!
Cheers
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Brian,
I use the full strength stuff only over open bays and only one coat at that. Everything else gets non-taunting. I also find that things stay in better alignment that way. The full strength taunting stuff can pull pretty hard.
Randy; does that mean the non-taut goes over the "full strength" dope ok?
Brian
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Brian,
It'll take a little sifting out, but the subject was hashed out pretty thoroughly right here...
http://stunthanger.com/smf/index.php?topic=19162.0
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Non-shrinking goes over shrinking dope absolutely fine! Just finished 2 little models (30" span) for my grandson, covered in silk scarves, 2 coats of shrinking nitrate (thinned) the rest was non-shrinking butyrate, (well thinned) no problems at all. I don't have to fuel-proof them as I'm using diesel engines!
Cheers
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Brian,
yea, as said above, the non-taunting goes over the taunting stuff fine. I don't use nitrate dope, though others do successfully. I use butyrate from the balsa up.
I've been talking to someone else about doing mixed finishes (in this case using lacquer and urethane). Compatibility becomes an issue mostly when you are using non-homogeneous material. There are ways to do it (like intercoats and seal coats between incompatible elements), but you always run a risk when using stuff that isn't made to work together.
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Brian,
It'll take a little sifting out, but the subject was hashed out pretty thoroughly right here...
http://stunthanger.com/smf/index.php?topic=19162.0
Thanks All for the feedback; and the link above; it was very helpful.
Brian
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The reason I used nitrate for the first few coats is, because it sticks better, personal experience as shown that! ;D As of the last couple of models, I've used sanding sealer, not home made, to stick the silk down and seal the bare wood. It doesn't lift fillets either. Clear dope is only used only on the open loose silk.
Cheers
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The reason I used nitrate for the first few coats is, because it sticks better, personal experience as shown that! ;D As of the last couple of models, I've used sanding sealer, not home made, to stick the silk down and seal the bare wood. It doesn't lift fillets either. Clear dope is only used only on the open loose silk.
Cheers
HI Neville,
Over the past close to 50 years, I have seemed to finally fall into a system I like and works, too. I used to only use Testors and Randolph dopes, because they were all that was available "locally". All were "butyrate". I did do a plane or two with Aero Gloss which I got on the rare trip to the hobby shop over 30 miles away. It wasn't "compatible" with the others at the time. As time has passed, I have taken tips from some of the best guys in the business: Windy, Bob Hunt, Billy Werwage, etc.. Bobby told me about Randolph's "Tinted Non-tautening Nitrate" years ago. He said to use it as a substrate, up to attaching the paper. I did and have done so ever since. I do like Randy P. and use Sig Supercoat (or some other high shrink butyrate) to shrink the open bays. Randy goes tend to use more full strength dope than I do, I thin everything, never using full strength (it will hardly ever "brush out" for me). I have then put dope, automotive lacquer, basecoat/clearcoat, urethanes, etc., over that. Final clear is either Sig Lite Cote, or urethane, depending on the plane. I no longer use ANY retarder.
I will say that you cannot use dope over a clearcoat/basecoat paint base color, it eats it alive. And never put nitrate over butyrate. ;D (but you can repair an automotive urethane clear finish with clear butyrate dope on open bays)
Big Bear
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Non Taut dope is a must... Even with carbon veil, which shrinks less than Silkspan, balsa isnt that strong without is. The issues are that with regual taut dope and silkspan is can " suck in " or warp the wood underneath. I have used moulded balsa shells for along time, and have used normal Taut dope to seal everything. Its IMPOSSIBLE.. read - IMPOSSIBLE, not to get some element of Suckdown over a shell. I have ( in the past ) resorted to laying down carbon fiber inside the shell, with more balsa doublers for a top block, yet still have the suckdown effect. - Which to fix results in more filler, more carbon, more work, more WEIGHT.
I finally gave up a few planes ago and went to Non - taut and carbon veil and the ship stays the way I finish it in wood, no suckdown no dips or gaps. No more fill.
I will even use a 50 / 50 mix of non-taut over the open bay to lay it down, - Starting with just putting it around the edges 1st, let it dry, then lay it over the bay - let that dry then put full strength over that - with no ill effects, no warping. If doing a fin for example, I would lay .02 carbon veil over that to aid in the finish and strength.
Any other way ( IMOH ) is a waste of time.