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The Effects of Heat on Wood

Wood has many purposes, from a walking stick to fuel for the fire. Wood drys, smokes, burns and chars, as increased amounts of heat are applied. The effects heat has on wood can be correlated to physical and chemical changes in the wood being heated. Properties of different types of wood also have been selected throughout the ages to perform special forms of heating, such as using maple wood for smoking or pine chips for burning.

Drying
- Drying is the effect of low-temperature heat on wood. When water is evaporated from the wood the wood will either shrink or swell, depending on the original moisture content of the wood. Lower moisture will cause shrinking and higher moisture will cause swelling, as the wood drys. Both shrinking and swelling will eventually lead to cracking, and wood with higher moisture content will take longer to completely dry.
Smoking
- Temperatures above 212 degrees Fahrenheit can cause wood to begin smoking. The effect heat has on wood at this temperature varies, depending on moisture content. Surprisingly, wet hardwood becomes pliable at these temperatures, despite smoking considerably. Smoking suggests that some chemicals -- mostly carbon dioxide and water -- are undergoing combustion reactions, creating smoke. A small portion of the smoke comes for the wood's composition, and creates smoky aroma of the wood.
Burning
- The effect of high heat, around 650 degrees Fahrenheit, is burning or ignition. This means, the bonds of the chemicals are becoming part of the combustion reaction. Burning require a consistent flame to ignite the wood. At higher temperatures, around 1100 degrees Fahrenheit, the wood will no longer require a flame and will spontaneously ignite. In this case, water vapor at high temperatures can spontaneously ignite a piece of wood. Burning different types of wood will result in a range of outcomes. For example, the amount of heat output and the length of burning will vary.
Charring
- The most noticeable effect heat has on wood is charring, and it is the hardest to predict. Wood that is burning on its own, or has become its own fuel source, is considered charring wood. How wood chars determines what type of wood should be used in home construction. Dry, light wood chars easily and hard, cured wood does not.

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