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Building Tips and technical articles. => Paint and finishing => Topic started by: Mike Callas on September 14, 2011, 10:28:06 PM
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OK,
Tried to finish my Oriental with Polyspan and dope.
I read as much as I could on the subject from this forum.
Butyr over nitrate, right hand wax, left hand wipe etc.
I covered the frame with nitrate thinned 50/50, 3 coats dried 2 days.
Polyspan went on dry and easy (shinny side up). Used a heatgun to pull out the wrinkles. Several coats of nitrate and it looked great-really.
Sanded between coats and it was real smooth.
I let it out gas for a week in the backseat of my truck (after 3 days the smell went away).
Then I tried brushing on some butyr clear before putting on the base color dope (Silver).
The butyr dope appeared to soften up the nitrate and now it looks like crap. The surface has a grainy appearance.
So, to quote Adolf Menjou from Paths to Glory, "Wherin did I go wrong"?
Should I have put a barrier coat of primer before adding the butyr?
Should I have shot the color straight on the nitrate?
Should I have watched a gladiator movie before starting?
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This is one of the reasons I gave up nitrate and went to butyrate from the wood up. No compatibility problems. But Ty is right. Just let it dry, make sure the covering is taunt, re-sand and prime as necessary. Then shoot color. It will be fine. Half the trick of any finish is knowing how to recover from problems. If a finish is going on too easily, I get nervous.
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That's been my experience with nitrate also. It looked OK until I put butyrate over the nitrate, and then it got kind of a mottled look to it. On some of the heat shrinks like Polyspan and Sig Koverall, I think they recomend that the first few coats be with nitrate. I am guessing that there may be adhesion problems with butyrate, although I have used butyrate on Koverall all the way without problems. The mottled look does not matter if you are going to put color over it.
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So Mike:
By 'grainy' do you mean that the underlying dope has wrinkled or otherwise changed shape, or do you mean that there's little dots of color?
If it's just appearance changes, then you're OK. If it's bumpy, but you've still got full adhesion, then you're OK. If your nitrate is gatored, then you've got big problems.
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Paths of Glory? Adolph Mejou? Just how olde are you. LOL LL~ LL~ LL~ LL~
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51, and I'm the baby at the field.
The last scene is my favorite.
Jim,
The first 3 coats were nitrate.
The surface looks like football skin.
WC fields once said "If at first you don't succeed, try, try again, then quit , no sense being a damn fool about it".
I'll continue my research and pick the brains of the local gurus, before I try this again.
I want to get this right before I build my Pentastar!
In the meantime I threw some color on it and plan to wear a bag over my head when I fly it.
Thanks guys
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I too now stay with Butyrate from the start. Then after a week or so after final dope coat I spray automotive two part clear. H^^
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Guys,
Seems like you should use the nitrate to adhere the Polyspan to the wood, then fill and finish with Butyrate.
Best, DennisT
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If you think that dope is giving you troubles then I'd suggest that before you use Monokote you locate some old stock before you start. The new Top Flite offering is really a pale shadow of the origional. It is hard to attach and even worse to shrink, plus it's a lot easier to burn a hole in it then any of the old covering was.. Forty five years of using Monokote and I've had it with it. Use Ultrakote and you should be as happy as a film covering can make you.
Dennis
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If you think that dope is giving you troubles then I'd suggest that before you use Monokote you locate some old stock before you start. The new Top Flite offering is really a pale shadow of the origional. It is hard to attach and even worse to shrink, plus it's a lot easier to burn a hole in it then any of the old covering was.. Forty five years of using Monokote and I've had it with it. Use Ultrakote and you should be as happy as a film covering can make you.
I took a long, long break from flying. So when I bought my first roll of the "new" monocoat I just thought that I had completely lost my touch. I can't say how relieved I was when I heard about the quality slip in the current product.