We've all seen darkened stocks, which seems to normally be attributed to dirt and oil. However, I recently did some reshaping of one of my own stocks and noticed the new wood was noticeably lighter in color than the old. This was English walnut finished with tung oil/urethane (waterlox sealer/filler and benmatte topcoats, pores completely filled, and was only about 2 years old.
So do you attribute this darkening to the wood itself, or to the finish?