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Questions and Answers

White stains on a black guitar

Q: I have a black Yamaha FG 411 acoustic guitar. Of late, there are these white stains which have appeared all over the body (front and back) of the guitar, which just won't come off.

Can you please suggest a way of successufully removing these horrifying stains off my guitar?

Regards,
Noel.

A: The finish on your guitar is catalyzed. It's like an epoxy coating. There is a wash coat to seal the wood, then Black color coats and then a clear top coat. Nothing sticks to this type of finish very well. Sweat stains would be white but would wipe off with water. The old nitrocellulose lacquers turned white when people spilled alcohol on them. The only thing that I can think of which would make a white stain on top of your finish, and would be hard to remove, would be a Superglue haze. Scratches and cracks in this type of finish are patched with cyanoacrolate, Superglue. As the glue dries a mist will condense on the finish near the repair. The police use this property of superglue to find fingerprints at crime scenes. If this is your problem, the surface should feel slightly rough. You should be able to raise a shine with McGuire's #7 buffing compound.

Your problem is more likely in the finish or under the finish. If you took a knife and scratched your guitar the scratch would appear white. There could be lots of tiny scratches looking like a white stain. These also could be buffed out but you would have to start with a heavier buffing compound and work down to #7. Lastly, there could be a bad joint between the black coat and the top coat. Fixing that would definitely exceed the value of the guitar. The guitar would have to be refinished. Black is a very hard color to match (actually all colors are essentially impossible to match) so the whole guitar would need to be refinished. Removing the old finish involves removing some of the wood that it's soaked into. In your case this is the top ply of your plywood back and sides. The grain in the next ply down goes the other direction. Don't go there. If this is your problem, learn to love your stains or sell the guitar to someone who can. Get your eye right down to your guitar in very good light. Use a magnifying glass even. You should be able to see if your facing door #1 door #2 or door #3.


Steve Mason


 


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