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Mixing paint types
Posted: Thu May 10, 2012 6:59 am
by Charles Bloss
I have been playing around with scrap trying to pick a good finish and color and I had something odd happen today. I sprayed a clear acrylic down to seal and level the wood and let it dry for a few days. I sanded it and sprayed a satin base coat on top of the clear and it dried really nice. I let that dry for about 12 hours and then shot the same clear acrylic on top but it instantly made the base color crackle and become rough. Both paints are from Krylon. Although I don’t want this to happen to my current project, it does make a interesting finish. What would cause this?
Re: Mixing paint types
Posted: Thu May 10, 2012 9:24 am
by Aaron Helt
I'd recommend checking the types of paints and the solvents in the mix. Sounds like the solvent of the clear is chemically hotter than the base. A hotter solvent can act like a stripper to another. One time, I was painting a new home I was having built and sprayed flat wall paint on the sheetrock. Then, the trim was installed and I primed the trim with nitro lacquer undercoating. All was fine until 6 months later, the flat wall paint was cracking and flacking off the wall everywhere the lacquer over-lapped the flat.
Re: Mixing paint types
Posted: Thu May 10, 2012 10:18 am
by Barry Daniels
Basically, this is one sign of incompatible coatings. It might look cool, but will likely not be stable in the long run like Aaron's example.
Re: Mixing paint types
Posted: Thu May 10, 2012 12:51 pm
by Rodger Knox
Was the satin base coat some kind of enamel? Lacquer over enamel will frequently have that effect, I'm not sure about acrylics. Most of the Krylon products are acrylics, but I believe they make acrylic enamel and acrylic lacquer, which may not be compatible. It's always safer to TEST ON SCRAP.
Re: Mixing paint types
Posted: Fri May 11, 2012 7:17 am
by Charles Bloss
I can't seem to find what type of paint these are. The clear only states acrylic. The satin finish doesn't say anything. It finishes similar to laquer that I have used before. The acrylic seems to build up like a good enamel. I just wish they would state that on the packaging.
This was only testing things I have leftover on scrap so no harm but I want to start planing out the color and finish of my current project.
What works best on bare wood, enamel or laquer?
Re: Mixing paint types
Posted: Fri May 11, 2012 12:57 pm
by Rodger Knox
In answer to your question, lacquer would probably be prefered over enamel, but for reasons that don't make much difference on a solid body electric. Either could be made_to_work equally well. That "made_to_work" means you'd have to test the entire procedure to verify compatibility between the sealer, pore filler, color coat, and clear coat, which you probably should do anyway. You MAY also need to develop some technique in the application to get your desired results.
A good finish can be cheap, quick, or easy. You only get to pick one!
Assuming you want to do a solid color sprayed from rattlecans, I'd recommend the auto parts store.
They have primer for a seal coat/pore filler, a wide range of colors for a base coat, and clearcoat to go over it, all formulated to work together.
I've never used this on a guitar, but then I've never done an opaque solid color on a guitar, and I don't spray finish on guitars.
Re: Mixing paint types
Posted: Wed May 16, 2012 8:30 pm
by Alan Owler
I have run into a problem like this before (just not on an instrument). Check the directions on the paint, some types have a time window for re-coating. The instructions can say something like "Re-coat within 1 hour or after 1 week". When I found out about this the second coat made the first wrinkle and crackle much like you're describing.
Al