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So I pull #5 down from the drying rack to start polishing out the Nitro and finish it up. RH in the house is down around 30% right now so not too bad. However, where this was stored is the dryest part of the house. I saw that the box was quite dehydrated so I throw a humidifier inside to puff it back up. Three days later all looks good except there are some hairline cracks in the finish around the edges of the soundboard. Sorry, no pics as it's sanded to 400 and the cracks just wont show.
The question is this. Will another coat or two of Nitro melt the cracks closed or do I need to strip and refinish the top?

Steve

Steven,
I would try a highly thinned mix and see if it melts it in, like mostly thinner.
There is a solvent designed for this but I don't remember what it's called, I think it might be called cellosolve from US Cellulose.

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Jim Watts
http://jameswattsguitars.com

Mohawk makes a solvent called Amalgamator that may work. It's designed to soften an old finish to get rid of water marks, finish cracks and crazing. I've used it on older nitro finishes and it worked well for me. It may be worth checking out.

http://www.mohawk-finishing.com/catalog ... 37&atomz=1

Cal

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Remember, there are no stupid questions, only stupid answers!

The Lacquer Melt is called Butyl Cellosolve. Be very careful as this compound tends to melt the lacquer AWAY!

I personally would recommend spraying another coat or 2 of nitro. You don't have to mix it too thin, just make sure that you spray a wet coat.

Mike Franks
www.mjfranksguitar.com

I didn't have very good results with Mohawk's Amalgamator, years ago when I used it , but I have had good results by spraying a coat of lacquer retarder and then giving it a plenty of time to dry, and I wouldn't be suprised if , as Mike Franks suggested, a couple of additional coats of lacquer wouldn't do the trick too.
jack

Nitro shrinks a lot, and continues shrinking for many, many years. If there are hairline shrinky cracks, even a couple more coats of finish will just shrink right back to where it is now, it will just take a while.

Sooo... either live with it(not a bad option if it is not for a customer) or its back to wood and deal with the surface. Adding lacquer or thinner will just prolong the innevitable.

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Jordan Aceto
Ithaca, NY

Thanks everyone for your help. I think I'm going to strip this one down and redo it. Now that it sat for two more days and a closer inspection, I've found more cracks in the finish than I saw before. One of these days I'm going to finish a glossy guitar on the first try!

Steve

Probably everyone here who has ever finished a guitar knows exactly how you feel, it sounds like you are taking it in stride like a champ. As bob taylor said, approximately "we should find out where the guy who decided it was a good idea to make guitars shiny by rubbing out lacquer finishes is buried, dig up his corpse, and shoot it."

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Jordan Aceto
Ithaca, NY

You'd probably have to shoot him again as he's already been shot the first time.

http://www.frets.com/FRETSPages/Luthier/Technique/Finish/Lacquer/CheckRepair/checkfill.html

I was thoroughly chastised for posting this link a while back.
But, doggone it, I would feel safe following Frank's advice.
Would it be worth trying a small area first without the razor blade widening technique?
(Just asking)

Well the top had too many checks to spot in so it's all sanded out with a fresh coat of sealer on it. The one check on the side and the one on the back are being dealt with using Todd's method.

Mr. Shiney Guitar's courpse shot? What he did was sick and wrong. Retribution should not be so easy for him.

Frank Ford is a stud.

I recommend against both the casual use of butyl cellosolve and inside-the-guitar humidifiers.

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Howard Klepper
http://www.klepperguitars.com

When all else fails, clean the shop.