Wednesday, January 28, 2009
Fortunately, I was able to rub most of it off with a cloth. I suspected it was some sort of mold, but I couldn't be sure. I was worried that it was caused by the dampits that I've been using a little obsessively these last few months due to the extreme low humidities. When I got home I inspected the interior of the cello and it appeared clean and dry - whew! no mold inside. Treatment with cello polish cleaned off all the residue, and the finish underneath the stain was just fine.
I realized it had to be coming from the case. There was a damp spot in the dark blue lining of the case that corresponded to the spot on the cello. The back of the case has a foam padding beneath the liner. I'm guessing that the extra moisture I'd been putting into the case via the extra-wet dampits was condensing into the foam pad and collecting at its base; and over time a mold had begun to grow on the liner against the back of the cello.
I left the the case open in front of a heater overnight to dry it out. The next morning I saturated the area with carpet cleaner and blotted it with a paper towel (which picked up some color) and then vacuumed up the residue after it dried. So, once again I've started squeezing the "free" water out of the dampits before putting them into the cello.
I've been asking myself since that night how this could have gone that far without me seeing it. I guess I just don't inspect the cello on any regular basis.