WHAT IS THE REDDISH BROWN STAIN ON MY WOOD?
Probably extractive bleed. Water-soluble substances called extractives are present in many species, especially ones with natural durability like western red cedar, Alaska yellow cedar and redwood, but also in Douglas-fir and some of the pines. These extractives can leach out of wood in moist conditions and “bleed” through many finishes. If excessive, these stains can interfere with coating adhesion. Remove stains by gently scrubbing with soap and water. Don’t use steel wool, as this can leave iron stains. Oxalic acid will remove these stains if soap and water isn’t effective; handle carefully and rinse thoroughly with water. Other possible sources of this stain: pine pitch leaching from a knot, or rust from a corroding fastener.
