My wife is an artist who uses guitars I build or renovate as her 'canvas'. She uses acrylic paint. On one previous occasion, I successfully stripped the soundboard of a used guitar back to naked wood using a sander and hand rubbing. That worked well.
However, I purchased a used dreadnought-shaped instrument the other day that has a light gloss varnish on the soundboard but a dark brown finish over the headstock, neck, heel, body sides and back. In a couple of places on the neck, the dark brown has been damaged which allows me to see that the finish has a significant depth above the wood - a bit like a coating. My guess is that this is, or is likely to be, nitro.
Would you confirm my guess or could it be poly?
In either case, it has to come off. Is the best way to strip off the dark brown using a chemical stripper or is another method preferred eg heat?
I plan to oil the neck and colour spray can prepare the body, the sides and the headstock and finally finish my wife's artwork with several coats of clear coat gloss.
Comments
The bad news is that if it's polyester, solvents or even stripper probably won't touch it. You will need heat - quite a lot of it, which is a problem if there's plastic binding - or to simply sand it off, which will be a huge amount of hard work.
In the less likely event that it's polyurethane, stripper might get it off. Probably worth a try first.
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One thing worth mentioning from my experience is that, on my guitar at least, the nice-looking top layer on the laminated sides is VERY thin and I did rub through it in a couple of places before I noticed - doesn't affect the way it plays of course but doesn't look that pretty. If you're planning on painting over it anyway then it doesn't matter so much.
The two small damaged places on the neck will lend themselves to a superglue repair so I'll leave them until I find out how hard it'll be to remove the stuff on the neck. It is a cheapo instrument with the label removed (in shame?!) so I'm assuming since it's all the same colour apart from the fretboard and the soundboard it'll all be the same stuff.
Thanks too for correcting me re polyester and polyurethane. The clarification means it's almost certainly polyester. Given the advice received here, I think my good lady, she who'll do the art decoration, will be persuaded to leave the dark brown stuff as is and to concentrate on the soundboard that I'm fairly confident will allow itself to be machine-, then hand-sanded.
Thanks again.
Stripping finish on cheap instruments usually leads to disappointment, in my experience, a lot of hard work to find a veneer or plywood, better left covered up.
I'm sure it depends on the finished art we are discussing, but getting the finish off these types of instrument is a daunting task.