Collings Baby- discoloring??

[marc51]

This was on reverb some time ago, and I had forgotten all about it.

The top is discolored where the arm rests when playing; first time I've ever seen that on a guitar.

Have any of you guys ever seen this type of discoloring?

Thank you,
m

[pto]

i've seen it on a lot of old martins and other well-played guitars. i've never experienced it, myself, maybe because i've always worn a long sleeve shirt - for sun protection.

[Frank Sanns]

There are many different finishes on guitars. Each one has a weakness.

Nitrocellulose is one of the easiest to be affected by solvents. It is by design, a polymer that dissolves in a solvent. Cure is by solvent evaporation and not by additional polymerization. This makes it prone to any kind of solvent that might be found in everything from oil based paint solvents to nail polish remover to gasoline and oil. Somebody that simply was around a paint spray booth with either no long sleeves or even with long sleeves could pick up some solvent. The playing the guitar would soften the surface up enough that dirt and other grime could slowly get to the surface and start a discoloration.

This can happen with varnish and urethanes too but different materials will attack those but by different mechanisms.

Hard to say what happened for sure but the moral of the story is to not have any lotion on your hands/arms when you are playing and beware any solvents of any kind that might adsorb up onto your skin/hair or a sleeve.

[armdog]

That can probably be fixed. An old master carpenter showed me some stuff about lacquer on my 74' CFM D12-18. (first guitar he ever held) He took clean old tshirt, dropped on some 3in1 oil, sprinkled on some H. Behlen Pumice stone (grade 4F fine powder). Rubbed it in over the entire surface. Then, I buffed it back to like new with my Woodcrafter buffing wheels.

From what I learned, that stain is probably only on the surface. .02c