This touches on a question I've had for sometime - sorry, no solutions.  I've an old gun (1860) in its case.  The wood that is "on top" when you open the case is a pleasing dark walnut.  Flip it over and the wood is much lighter, almost a "blonde". 
I've wondered if once, for decades, the gun was displayed in a rack of some sort and the blonde side was exposed to sunlight, could that have lightened the wood?  Or the inverse, the darker side was exposed. The uneven effect is somewhat disheartening, especially because the wood has such beautiful figure. 
Last edited by Krakow Kid; 01/09/11 07:14 PM.