Drying Green Wood - Page 2 of 2 - Popular Woodworking Magazine

Drying Green Wood

 In Techniques

One thing to remember is that once your lumber has dried, it can’t get any drier, so lumber that has air dried for many years isn’t any drier than lumber that has dried for just the right amount of time. Once your lumber is as dry as it can get, you can re-stack the lumber somewhere else without stickers for easier storage.

Air drying your lumber outdoors won’t get you down to the ideal moisture content to successfully use your lumber indoors. Wood used in the home should range around 6 to 8 percent moisture content. Air drying outdoors only allows the lumber to reach its equilibrium moisture content (EMC) with the surrounding air, which is typically 12 to 18 percent. While air-dried lumber can be used as-is with adequate consideration for shrinkage, you will be better off drying it indoors before using it.

To dry your lumber indoors, use essentially the same stacking technique, without the special considerations for moist ground, sun and rain. It is important to stack the lumber in a dry area where there is air circulation. While it is tempting to do this in the basement, it may be too moist to do this effectively. If in doubt, use a dehumidifier to control the humidity.

Finishing the drying process indoors will take from several weeks to a couple of months, depending on conditions in your home and the moisture content you are starting with. You don’t need to dry all your lumber indoors at once. If you plan your projects properly, you can dry enough in small batches to satisfy your project-making goals. To be certain the lumber is dry enough, check the moisture content before using it. PW

Measuring Moisture
You can measure the moisture content of your lumber in three ways:

Moisture meters • They are available at various prices and various moisture ranges. Traditional meters use pins that are pressed into the wood for a reading, while pinless meters allow you to check moisture without damaging the wood.

Consistent weight method • To determine if boards being dried indoors are dry enough to use, weigh one board at the start of the process and then once every week. Plot your results. When the weight starts to remain constant, the lumber is sufficiently dry.

Oven method • Accurately measure the weight of a small sample (no more than a 1″-thick cross section) of your lumber and dry it in a 212-degree oven until it is dry (up to 24 hours). Weigh the dried sample and subtract its current weight from its original weight to find the weight of the water that dried off. Divide this by the dried weight of the wood and multiply by 100 for the moisture content.

Michel Theriault lives in Ottawa, Ontario, Canada.

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