I have been having a less than entirely fun experience painting a resin-cast Mark VII tricorder.
I primed with self-etch, painted with Krylon gloss acrylic, sanded, dusted with Krylon silver, and then applied a lacquer clear coat (Watco Clear Satin). Unfortunately, anything other than the lightest of mistings of the clear coat causes the topcoat to wrinkle and crack down to the primer. Very light mist is fine, but anything enough to wet the surface markedly tends to cause this monstrosity:
Which means I have to sand back down to around the border of the primer and gray and start over.
Some experimentation has led me to the conclusion that this is an issue of a chemical incompatibility between the acrylic and lacquer. Namely, the lacquer seems to be acting as a solvent to the acrylic, even though it is entirely dry. I have another prop that I painted using laquer-based paint and I tried applying the same laquer clear coat on top of that copiously (far more than the tricorder ever got) and there was no sign of cracking at all. So, as I say, it seems to be an issue of incompatibility between the chemicals. Why the problem doesn't occur with just a light misting is entirely a mystery to me, but using many very very light coats actually does work, notwithstanding the anxiety of trying to apply it without overdoing it.
Here is my puzzle: now that I've managed to get the prop to accept a clear coat using the lacquer with multiple light coats is also when I have worked out the cause of the problem, so my question is: should I sand everything back down and start over, or leave it as it is (looking fine now) and just cross my fingers that something isn't going to do wrong down the road? My fear is that somehow the lacquer coat is going to dissolve the paint over time and end up cracking anyway.
Any other ideas as to what's going on here chemically or in terms of my technique would be most appreciated. My surmises above may be entirely incorrect.
I primed with self-etch, painted with Krylon gloss acrylic, sanded, dusted with Krylon silver, and then applied a lacquer clear coat (Watco Clear Satin). Unfortunately, anything other than the lightest of mistings of the clear coat causes the topcoat to wrinkle and crack down to the primer. Very light mist is fine, but anything enough to wet the surface markedly tends to cause this monstrosity:
Which means I have to sand back down to around the border of the primer and gray and start over.
Some experimentation has led me to the conclusion that this is an issue of a chemical incompatibility between the acrylic and lacquer. Namely, the lacquer seems to be acting as a solvent to the acrylic, even though it is entirely dry. I have another prop that I painted using laquer-based paint and I tried applying the same laquer clear coat on top of that copiously (far more than the tricorder ever got) and there was no sign of cracking at all. So, as I say, it seems to be an issue of incompatibility between the chemicals. Why the problem doesn't occur with just a light misting is entirely a mystery to me, but using many very very light coats actually does work, notwithstanding the anxiety of trying to apply it without overdoing it.
Here is my puzzle: now that I've managed to get the prop to accept a clear coat using the lacquer with multiple light coats is also when I have worked out the cause of the problem, so my question is: should I sand everything back down and start over, or leave it as it is (looking fine now) and just cross my fingers that something isn't going to do wrong down the road? My fear is that somehow the lacquer coat is going to dissolve the paint over time and end up cracking anyway.
Any other ideas as to what's going on here chemically or in terms of my technique would be most appreciated. My surmises above may be entirely incorrect.