Tannins and Wood

Time-Tested Performance

Many wood species contain naturally occurring, water soluble chemicals that tend to migrate to the surface with exposure to extracting agents. During the application of Seal-It Wood Sealant to previously untreated wood, coffee or tea-colored fluid may appear on the wood surface or flow down a wooden wall. When tannin extractives that are dissolved by the Wood Sealant, reach the surface they may remain as dark, coffee-brown stains after the sealant “cures”. This brown-black bleeding is unsightly, but not damaging to the wood, or sealant.

Much of the tannins can be easily removed, while in the liquid state, by flushing with water; follow this flushing by re-application of Seal-It Wood Sealant. Tannin “bleed” does not occur on wood that has been treated with Seal-It Wood Sealant.

Should there be a situation where the tannins reach the surface of the wood but do not get flushed away before drying, you may need to use Seal-It Maintenance Cleaner and a stiff bristle brush or broom to remove the stain.