Tips for preventing wood surfaces from cracking

Although woodworkers hate cracks, they can seem to be a fact of life, especially when you're working with large pieces. In this blog, we'll look at ways you can minimise their impact...or eliminate them entirely.

Let's first consider how cracks develop.

As befits a once-living material, wood is mobile and responsive to changes in its environment, shrinking or expanding with humidity levels and other factors. These movements occur through every part of the piece, so the centre of a block of timber ought to change size just as much as its outside surfaces.

It doesn't always work out that way.

Firstly, wood is often subject to very sudden changes. The obvious example would be a house move accompanied by a rapid reduction in humidity or an increase in temperature. Those changes will eventually cause the entire piece to grow or shrink, but in the short term the outside of the wooden object may be affected more than its inside. Such conditions breed differential stresses in the wood, and the result is often a crack - most commonly starting at the cut ends of the wood fibres and extending into the piece along its grain.