Oakum

Oakum, a tangled mass of tarred hemp fibres, is made from old rope by untwisting the strands and rubbing the fibres free from each other. Its principal use is in Caulking (q.v.) the seams between planks, the space round rivets, bolts, &c., for the purpose of preventing water from penetrating. The teasing of oakum is well known as an occupation for prisoners in jail.