Joint of the Week: Butterfly Key

George Nakashima often used butterfly joints to stabalize the massive slabs of wood that he used in his work. They can be used either to hold two or more wooden slabs together or to keep two halves that have already started to split from splitting further. When done properly, a butterfly key will actually draw the crack together and inhibit further movement of the crack.

 A butterfly key looks like two dovetails joined at the narrow end. The then negative is cut from the board and the butterfly is fitted in.

The key is often made of contrasting wood as in Nakashima's work, but it was also used for repairing cracks as early as the 18th century, when the butterfly was hidden on the underside to stabalize a crack.