This has worked for me. Maybe everybody already knows it. I felled some large pines and hauled them away to make lumber. All cut at 7/8ths inch thick and up to 16 feet long. Many are 16 inches wide. Anyway I got the boards in all wet (green) last summer and stickered them up for drying. Winter hit and they did'nt dry for months. Got black mold stain all over their pretty surfaces and down to about one millimeter deep. I bought the cheap WalMart large jugs of bleach and sprayed it (straight, no dilution) on to the boards. The mold and spores is of course killed and the stains bleached out well. Its southern yellow pine and the boards themselves are much lighter. Looks good.