This may be a dumb question, but is it possible to remove, or at least make less noticeable, stains that occur on wood while air-drying? Also, how do I avoid this next time?
I have approximately 125 board feet of birch air-drying in a shed, and there's now a black stain on some of the boards. There's no stain under the stickers.
The black stain is probably mildew (but not for certain, since I haven't seen the wood). It can be removed by planing. Oxalic acid can be used on some stains to bleach them, but not fungal stains such as mildew.
These stains result because you are drying the wood too slowly -- poor air flow and high humidity.
Gene Wengert, forum moderator