Regarding Paul Lehrman's inquiry [131220 MMDigest] about the
discoloration on a recently moved grand piano case.  My best guess
is that the finish is separating from the wood.

Now, before you get too alarmed, I'll say that this is not unusual.
As finish ages it becomes harder, especially the old type of varnish
they used back then.  The finish gets to a point where it cannot expand
and contract with the wood during seasonal changes and causes the
surface to crack.  Technically this takes place early on in the life of
a finish, and depending on it's environment and care through the years
(waxing and oiling) the condition may never be too noticeable.

You've probably seen the extreme of this condition called "alligatoring".
Also, you've probably heard of or seen where a glass of water made a
white ring on a seemingly good finish.  That's when the moisture has
gone through those little microscopic cracks and separated the finish
from the wood causing discoloration.

Basically, on a larger scale, that's what is happening to the finish on
your piano.  The roughness you feel is the finish actually coming loose.
For it to show up suddenly is evidence it has gone through some sort of
climate change.  The reason it's only evident on the case is the result
of it's positioning relative to light exposure through the years, we
see this often on grands.  Most likely the veneer on the damaged areas
is "sun-bleached" a little as well.

There are a couple of "quick fixes" for that condition.  There are
products that will amalgamate the finish together again, but as a
refinisher I've never been too impressed with the results of that.
Also, some modern lacquers will melt old finish together when sprayed
over the top.  This looks a little better but again is only a quick
fix.  Of course, as a piano refinisher I would be remiss if I didn't
recommend a total refinish job from a professional refinisher
_specializing_ in piano refinishing.  As you know, your piano is worth
it.

Ken Marts
Oregon