Control Splitting While Seasoning

Issue: Issue 229
Posted Date: 8/11/2009

I want to know how to control splitting of wood in the seasoning process.

T. C. Knight: The technical term for splitting of boards during the drying process is checking. Checking is caused by the exposed capillaries at the ends of the boards losing moisture faster than the sides. Reducing excessive end drying will reduce the amount and severity of end checks. The best way to control checking is to paint the ends of the logs with a good exterior paint soon after cutting the tree. The paint slows drying on the ends of the boards so that the board dries more evenly and reduces the stresses that cause checking. Another cause of checking is drying the wood too quickly. Lumber drying should be a controlled process that takes an appropriate amount of time to allow moisture to gradually escape from the wood so that the wood fibers can adjust to the reduced pressure.

John Brock: Splitting and checking occur when the moisture goes out of the wood too fast. On average, end grain gives off or absorbs moisture 15 times faster than side grain. This means you need to seal the end grain to keep it from seasoning too fast. Paraffin wax or latex paint both work pretty well. To slow down the moisture from the side grain, stack the planks on thin strips of wood called stickers, and throw a tarp over the pile. This will let air circulate between the planks, but in a controlled way so it doesn't season too fast. Slower is better.