I have this piece of cherry (American) heartwood. It had a sticker on it. When I peeled it off there was a lighter area underneath. It is not residue from the sticker (I scrubbed it with xylene), the wood is discolored. I am not sure how deep it goes but I was unable to affect it with heavy sanding.
My question is: What caused that? Was it some chemical in the glue? The paper? Trapped moisture? No oxygen, or blocking sunlight?
I'm not concerned about getting rid of it (that piece lives in the scrap bin now) but I'm curious about the chemistry behind that discoration.