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Building Tips and technical articles. => Paint and finishing => Topic started by: Dan McEntee on April 13, 2019, 07:10:42 PM
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This has been in the forefront pretty regularly with the popularity of rattle can paint jobs. I was going through some magazines today that came from the estate of a club member that passed away several years ago, Virgil Diekmann. Some of you may remember him. In one of the Model Aviation magazines from August, 1993, in Bill Boss' scale column, there was mention of a book on building model airplanes (FYI-Model Flight) and inside was a small chart on chemical compatibility, in other words, what can go over or under what! The column is on page 78 and those that are still AMA members can view it on the website. Maybe one of the computer wizards can copy it and pin it to the top of the painting and finishing section? It might save a lot of grief for new comers. Bill Boss was one of THE top control line scale builders and wrote that column for a long time as was one that I always and least glanced at, so you know the info should be correct.
Type at you later,
Dan McEntee
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Hey Dan, I looked in my files and found this. it isn't the best resolution but should be able to view it.
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Hi Joe;
Yeah, that is the same chart. I just can't read what is along the bottom. It's not on the chart in the scale column though. If some one can clear it up to where it can be read we can just add it to this thread, then maybe pin it to the top of the forum. The only one I can't agree with right off is the vinyl spackle. I've never had any luck with anything going over that when used as a fillet material. Everything always lifted off of it. This should cover all of the basics, though.
Thanks a lot,
Dan McEntee
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Whisky over wine is fine.
Wine over whisky is risky.
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Same but different.
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Hey Dan, I looked in my files and found this. it isn't the best resolution but should be able to view it.
I just recently came across this same chart on the "Model Flight" web site by Larrry Davidson for old timer model airplane supplies. The statement at the bottom of the chart:
"NOTE: This information was copied from the February issue of Hot Air the newsletter of SAM 59 model airplane club which their editor got from the AMA National Newsletter. It is credited to the Rocky Mountain Aeromodelers. It was also published in the August issue of Model Aviation."
Which August issue of Model Aviation is not shown.
Keith
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So I'm guessing Rustolium is acrylic enamel and ok to spray over epoxy, superpoxy, Klass Coat or Zpoxy?
It won't curdle it up. "Compatible" means it won't melt it or craze it, or wrinkle it up. That doesn't mean it will stick very well. Many of the combinations in this list are notable for poor adhesion and/or other problems. Test carefully any planned mixing of materials.
Some examples (that I happen to know about, but being very far from an expert on):
SIG Dope will sometimes just lie like a film on some batches of Brodak dope, like you had painted it on glass, and it peels up cleanly. Other batches of Brodak dope are OK. I have no way to identify which are which
Butyrate Dope doesn't stick very well to epxy, particularly after the first week of curing.
Silver butyrate dope tends to act like teflon, and nothing seems to stick to it very well.
Epoxy over butyrate dope tends to trap the (eternal) outgassing and bubble up
Butyrate dope will not stick to "lightweight" spackle (Model Magic, etc) and will soften it up, maybe permanently
Plasticizer in dope greatly reduces the adhesion of anything over it
Epoxy doesn't stick very well to butyrate dope (any kind)
Different batches of Aerogloss are incompatible with each other, and will immediately "craze" the underlying paint, like a million little cracks
Butyrate dope has minimal adhesion to Epoxolite. It sticks better to Aeropoxy and really good to SuperFil
Anything in a spray can is a crapshoot, and two identical cans/part numbers might have different ingredients
These are just the ones I can think of off the top of my head, and came from experience, witness the results, or first-hand from reliable sources.
Brett
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It won't curdle it up. "Compatible" means it won't melt it or craze it, or wrinkle it up. That doesn't mean it will stick very well. Many of the combinations in this list are notable for poor adhesion and/or other problems. Test carefully any planned mixing of materials.
Some examples (that I happen to know about, but being very far from an expert on):
SIG Dope will sometimes just lie like a film on some batches of Brodak dope, like you had painted it on glass, and it peels up cleanly. Other batches of Brodak dope are OK. I have no way to identify which are which
Butyrate Dope doesn't stick very well to epxy, particularly after the first week of curing.
Silver butyrate dope tends to act like teflon, and nothing seems to stick to it very well.
Epoxy over butyrate dope tends to trap the (eternal) outgassing and bubble up
Butyrate dope will not stick to "lightweight" spackle (Model Magic, etc) and will soften it up, maybe permanently
Plasticizer in dope greatly reduces the adhesion of anything over it
Epoxy doesn't stick very well to butyrate dope (any kind)
Different batches of Aerogloss are incompatible with each other, and will immediately "craze" the underlying paint, like a million little cracks
Butyrate dope has minimal adhesion to Epoxolite. It sticks better to Aeropoxy and really good to SuperFil
Anything in a spray can is a crapshoot, and two identical cans/part numbers might have different ingredients
These are just the ones I can think of off the top of my head, and came from experience, witness the results, or first-hand from reliable sources.
Brett
Damn, I wish I had seen your list 20 years ago (!)
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My brother reported that polyurethane clear on his PRC produced "oak" toilet seat didn't harden and was forever sticky to sit on. I'm guessing that he disposed of the seat in an environmentally safe manner, since he lives in California. We figured that the stain used on the seat was latex based, which caused the problem. LL~ Steve
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Interesting how one chart says Dope over Lacquer is ok and the other chart says no way