Ability of bleach and other biocide treatments to remove and prevent mold growth on Douglas-fir lumber

Molds are an increasingly important issue for all building materials, including wood. While washing with bleach is a commonly recommended method for removing molds, and the associated discolorations, there is surprisingly little information on the effectiveness of this treatment. The ability of mold removal treatments to brighten wood and eliminate fungi was assessed on Douglas-fir (Pseudotsuga menziesii) sapwood lumber heavily colonized with mold and sapstain fungi. The boards were subjected to different washing treatments: wiping with bleach solution, wiping with water, and a no-wash control. Samples were evaluated visually for changes in mold appearance and then fungi were isolated from the surface of the wood. Replicates from the various wash treatments were further treated with three biocide formulations. The effect of the mold control treatments on visual appearance and fungal diversity was assessed 1 month after treatment. Increasing bleach concentrations from 2.5 up to 20 percent solution had no effect on the appearance of the wood following the wash treatment, nor did such treatments completely eliminate fungi from the wood surface. The chemical mold prevention treatments tested were not effective in sterilizing the wood, nor did they improve the visual appearance.

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