Mold & Mildew

Why mold develops

Moldy wood is often a precursor to rot or decay. Severe rot and decay can appear around corners or base logs, which may point to a moisture problem that can be addressed with gutters, flashing, or other drainage solutions.

Mold grows whenever temperatures are above freezing and thrives above 70°F / 20°C. It needs three things to survive: warm temperatures, a food source, and moisture. Remove any one of these factors and mold cannot grow.

Mold on new or unfinished wood

Freshly peeled or milled logs can bring sap to the surface, creating a food source for mold spores. Mold spores are tiny airborne seeds found almost everywhere and can grow into colonies when temperature, food, and humidity are right.

If mold has started and is killed, discoloration may remain. Clean the surface with a sodium carbonate base product and/or Ultra-Brite before using any MENCO product on interior or exterior wood.

Moisture guidelines

Most wood should have a moisture content of 18% or less before staining. Cedar, redwood, and cypress should be 12% or less. Use a moisture meter to check the wood.

As a simple check, spray water on the wood. If it penetrates immediately, the wood may be ready to stain. If water beads and remains on the surface, surface moisture is too high. High moisture can allow mold and mildew to develop under a finish.

Moisture content explained

Greenwood has 30% moisture or more and may reach 100%. Surface-dry wood has 25% moisture or less and is commonly seen two weeks to four months after cutting and debarking.

Dry lumber has 18% moisture or less; cedar, redwood, and cypress should be 12% or less. Kiln-dried wood has 15% moisture or less and is more dimensionally stable.

A note on Men-Wood finish

Men-Wood contains fungicides to help fight surface growth. Mold and mildew are natural worldwide occurrences, and Men-Wood Coatings cannot assume responsibility for their formation on wood or logs.