ToddW Posted November 2, 2008 Report Share Posted November 2, 2008 Help please. I sealed the solid body guitar I'm finishing with a couple of 1# cut coats of de-waxed shellac and sanded it to 320. Then I put down 3 coats of pre-cat lacquer each an hour apart per the instructions, sanded to 600g after each. I then repeated this the next day. 3 days later I sanded up through 12,000 grit and was planning to buff it later. That was about 2 or 3 weeks ago. I worked a little on the electronics yesterday and it looked fine, but today I saw what looked like deep linear dents in the finish radiating out from the tail piece studs and a couple from the tone control holes. The feel like dents too, but I think there's a very fine crack in them. Any idea what caused this? Clearly I have to sand to wood and redo this, but I'm clueless on the cause. Thanks, Todd Quote Link to comment Share on other sites More sharing options...
ToddW Posted November 3, 2008 Author Report Share Posted November 3, 2008 Well, I think I figured it out somewhat. In sanding it off outside dusted up easy, but once I got through the outer part, the finish underneath was soft and still had a solvent smell. To the point where I'm letting it cure overnight since it is too soft to sand off easily. So . . . guess you can put one or two coats down after an hour, but clearly I exceeded the maximum thickness. I'll sand off the top, the back and sides are thinner so I'll see how that goes, and then I'll re-coat. But clearly I'll let it cure much longer between coats! Todd Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted November 3, 2008 Report Share Posted November 3, 2008 I've never used pre-cat laqcuer - it is a nitrocellulose product like regular lacquer? I use a pre-cat conversion varnish and I never end up needing more than 3-4 coats, and that's with 20% thinner. It can be levelled after a day or two, but it ends up being much harder, and levels and buffs out nicer, if I let it set for two weeks. After 2 weeks you can't smell the solvent coming out. Quote Link to comment Share on other sites More sharing options...
ToddW Posted November 3, 2008 Author Report Share Posted November 3, 2008 I've never used pre-cat laqcuer - it is a nitrocellulose product like regular lacquer? Hi Erik, I think it's basically a mix of some nitrocellulose lacquer and a conversion varnish. The nitro makes it act like acquer, and I would guess helps with adhesion of multiple coats. I think it also means you need to let the lacquer thinner flash off before you cover it with more varnish. I probably went too thick and too fast. Live and learn . . . Quote Link to comment Share on other sites More sharing options...
erikbojerik Posted November 3, 2008 Report Share Posted November 3, 2008 Yep - the CV I use will dry to the touch in 10-15 minutes at 75°F, but if I end up laying down a coat that's too thick, it will skin over and I'll get tiny bubbles accumulating under the skin as the bottom of the layer tries to gas off. Quote Link to comment Share on other sites More sharing options...
ToddW Posted November 4, 2008 Author Report Share Posted November 4, 2008 I didn't see any bubbles, but the checking was bad enough. I've almost got it sanded off. Just the edges are still coated, and I'll have to sand those off by hand. It was a good learning experience Quote Link to comment Share on other sites More sharing options...
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