Oakum

It is also referenced frequently as a medical supply for medieval surgeons, often used alongside bandages for sealing wounds.

History

The word oakum derives from Middle English okome, from Old English ācumba, from ā- (separative and perfective prefix) + -cumba (akin to Old English camb, "comb")—literally "off-combings".

Oakum was at one time recycled from old tarry ropes and cordage, which were painstakingly unravelled and reduced to fibre, termed "picking". The task of picking and preparation was a common occupation in prisons and workhouses, where the young or the old and infirm were put to work picking oakum if they were unsuited for heavier labour. Sailors undergoing naval punishment were also frequently sentenced to pick oakum, with each man made to pick 1 pound (450 g) of oakum a day.

The work was tedious, slow and taxing on the worker's thumbs and fingers. In 1862, girls under 16 at Tothill Fields Bridewell had to pick 1 pound (450 g) a day, and boys under 16 had to pick 1+1⁄2 pounds (680 g). Over the age of 16, girls and boys had to pick 1+1⁄2 and 2 pounds (680 and 910 g) per day respectively. The oakum was sold for £4 10s (equivalent to £494 in 2025) per hundredweight (112 lb, 51 kg). At Coldbath Fields Prison, the men's counterpart to Tothill Fields, prisoners had to pick 2 lb (910 g) per day unless sentenced to hard labour, in which case they had to pick between 3 and 6 lb (1.4 and 2.7 kg) of oakum per day.

In modern times, the fibrous material used in oakum comes from virgin hemp or jute. In plumbing and marine applications, the fibers are impregnated with tar or a tar-like substance, traditionally pine tar (also called "Stockholm tar"), an amber-coloured pitch made from pine sap. Tar-like petroleum by-products can also be used for modern oakum. When working on HMS Victory in the 2020s hemp combined with Jeffery’s Marine Glue was used.

"White oakum" is made from untarred material, and was chiefly used as packing between brick and masonry in homes and building construction prior to World War II, as its breathability allows moisture to continue to wick and transfer through the material.