Crazing in water-based lacquer - created 07-05-2011

Baker, Dan - 07/05/2011.20:31:33

I am using S-M's ColorTone water-based lacquer/sanding sealer to finish my guitar, using an HVLP system. Spraying 3-4 light coats per day, 4 hours apart @ 65-70 degreees, 45% humidity. I shot 12 coats of sanding sealer, and level-sanded. Everything looked good. I made a toner using the water-based lacquer and some S-M ColorTone Liquid Stain, and shot two light coats. Then began applying top coats using the lacquer. After 4-5 coats, I noticed that the finish was very uniformly crazed all over. I hope it shows up in the picture. The crazing is a bit exaggerated in the soundboard extension area, which I had masked off prior to spraying, but very much like the crazing on the actual finish. The only possible theory I've found is a possible disparity in the evaporation rates of the toner and the lacquer. But as they are from the same family of products, and designed to work together - I am a little skeptical. As it turns out, it's not a bad look since I am going for a vintage vibe anyway. But I would prefer to make that decision rather than have it made for me. I would appreciate any theories.

Image

sysop - 07/05/2011.20:34:41
Deb Suran

Wow. That crazed fast! Looks like the finish on an old piano.

Swanson, Mark - 07/05/2011.22:24:29
MIMForum Staff, Michigan

My first guess would be that the finish is too thick, the 12 coats of sealer is too much and there might be something going on between the two products.

Clay - 07/05/2011.22:25:23

If the toner in the finish slowed the evaporation and you oversprayed it with a faster evaporating top coat it could cause the top coat to alligator or craze when it did dry and shrink.

!2 coats of sanding sealer sounds like an awful lot! It often contains stearates, soap like substances to make it easy to sand. Too much sanding sealer can affect adhesion adversely.

Brackett, Woodrow - 07/06/2011.05:06:15

I've heard of others having similar problems that were cured by adding retarder to slow the curing time. I believe you'll need to strip the crazed finish.

I'd recommend something besides a waterborne finish.

Baker, Dan - 07/06/2011.07:50:57

Agree it seems like a lot of sealer. But I had quite a bit of orange-peel, so I felt that I ended up removing a good amount of it during the leveling.

Tweedy, Chuck - 07/06/2011.11:52:12
Midnight Lutherie ... because that's when I work

Did you talk to Stew-Mac?

If you are following their recommended schedule, they should be able to help you.

Duross, Dennis - 07/06/2011.18:53:19

I know this is of no possible use, but that looks really cool.

Baker, Dan - 07/07/2011.11:11:19

It's easy enough to start over, I'll adjust the gun to shoot lighter and see how that does. I would like to know how to do this intentionally though, just for the heck of it. When I pulled off the masking film, the finish that had built up on it broke into a million little pieces - very brittle. They measured out at .006" thick. So anyway, thanks for the input - I will stumble blindly forward, it's how I roll.