In addition to fungi, weather is the other cause of wood deterioration.

The major factors in the weathering process are:
- Ultraviolet rays (sunlight)
- Water
- Temperature
- Abrasion

Ultraviolet rays – UV causes a breakdown in the lignin component of the wood cell which gives rise to color changes. Light woods tend to darken and gray. Dark woods bleach out and gray.

Water – It plays a major role in weathering of wood. As UV causes lignin to degrade, water washes away surface cellulose fibers that have been released due to the breakdown of lignin. As these surface fibers are washed away, new fibers are exposed and the cycle continues. Water also causes swelling and shrinking of the new wood surface, developing cracks which expose new wood fibers to UV breakdown.

Temperature – It is not as critical a factor as UV and water, but increased temperature accelerates the deterioration process caused by UV. For log homes, elevated surface temperatures will increase the rate of moisture release within the logs thereby causing more checking. That’s why it’s a good idea, especially on new log homes, not to use dark color stains, since darker colors will absorb and hold heat and accelerate the release of moisture. Also, freezing and thawing of absorbed water contributes to checking as well.

Abrasion – The mechanical action of wind, sand, and dirt can be an important factor in the rate of surface degradation and removal of wood. Small particles such as sand, can become lodged in surface cracks and through swelling and shrinking, weaken fibers in contact with it. Solid particles in combination with wind, can have a significant sandblasting effect. A log home in a treeless field is especially vulnerable to abrasive weathering.

This sections content was provided by The Continental Products Company.