Logwood, or bloodwood, is a tree that is native to the West Indies and South America. When the ground heartwood is soaked in water it makes a blood red liquid which can be used as an indicator solution, changing colour depending on what is added to it. Used as a dye it can produce a range of colours from black and purple to a delicate fawn.

Aztec and Mayan cultures used logwood for centuries, and it was highly prized when it was first brought to Europe by the Spanish in the 15th Century. In the 1570s Elizabeth I of England ordered privateers to seize Spanish logwood cargoes, escalating hostilities between the two countries and leading, in 1588, to the sinking of the Spanish Armada.