A burl is a growth on a tree that is the result of some form of stress the tree has been subject to. The tree repairs itself by growing over the stress point, eventually creating a burl.  They occur only on a small percentage of trees, thus making the supply of burl wood limited.  I enjoy turning burls and usually end up with a distinctive piece, as I never know what colours and patterns I will find inside the chunk of wood I started with.

It is hard work to reveal the inner beauty of a burl, particularly if it's been off the tree for many decades before turning. A number have disintegrated and flown off the lathe before completion due to extended cracks, bark intrusions and general weakness.  This is just part of the challenge and also why I wear a full face protective helmet!