Discoloration on underside of pinblock

[Andrew & Rebeca Anderson]

I've seen this in Delignet pin-blocks where the underside was sanded 
thinner in places to better match the case.  The glue layers come out as 
"stained".  Of course when sanding, as opposed to planing, you can end up 
with a blotchy (irregular depth) pattern.

Andrew
At 07:36 PM 5/27/2005, you wrote:
>New customer today with a gorgeous Yamaha C7, 1993.  It was in Tennessee 
>for a while, and has been out here for several years.
>
>I felt the edge of the pinblock through the half-opened fallboard, and 
>felt ripples in places.  Removing the fallboard, the underside was stained 
>dark in large areas across about a third of it, like a walnut stain (wish 
>I had a picture).  In some places, there were thin white lines in the 
>shape of the grain, with broad dark lines between them (where the harder 
>wood didn't absorb the color?).
>
>The color didn't scrape off with a fingernail.  In the dark areas, I could 
>feel ripples, parallel to the bass strings (from the milling machine, 
>perhaps?).  The light areas were very smooth.  No other stained areas in 
>the action cavity.
>
>Pin torque was tight.  No signs of moisture damage, save that if you 
>caught a reflection off the soundboard just right, you could see a few 
>cracks starting to form in the varnish, along the glue joints.
>
>Any ideas as to the cause?
>
>--Cy Shuster--
>Bluefield, WV
>