Oakum is a preparation of tarred fiber used to seal gaps. Its main traditional applications were in shipbuilding, for caulking or packing the joints of timbers in wooden vessels and the deckplanking of iron and steel ships; in plumbing, for sealing joints in cast iron pipe ; and in log cabins for chinking . In ship caulking, it was forced between the seams using a hammer and a caulking iron, then sealed into place with hot pitch. [1]

Oakum was at one time recycled from old tarry ropes and rope, which were painstakingly unraveled and taken apart into fiber. This task of picking and preparation was a common occupation in prisons and workhouses , where they were often put to work when they would no longer perform heavier labor. Sailors undergoing naval punishment were also frequently unpicked, with each man made to unpick 1 pound (450 g) of oakum a day. The work was tedious, slow and taxing on the worker’s thumbs and fingers. [1]

In modern times, the fibrous material used in oakum comes from virgin hemp or jute . The fibers are impregnated with tar or tar-like substance, traditionally pine tar (also called ‘Stockholm tar’), an amber-colored pitch made from pine sap. Tar-like petroleum by-products can also be used for modern oakum. White oakum is made from untarred material.


The word oakum derives from Middle English okome , from Old English tocumba , from to- ( separative and perfective prefix) + -cumba (akin to Old English camb , “comb”) – literally “off-combings”.

Picking oakum was a common occupation in Victorian times in British prisons and workhouses . In 1862, girls under 16 at Tothill Fields Bridewell Had to pick 1 pound (0.45 kg) a day, and boys under 16 Had to pick 1 1 / 2  pounds (0.68 kg). [2] Over the age of 16, girls and boys Had to pick 1 1 / 2  and 2 pounds (0.68 and 0.91 kg) per day respectivement. [2] The oakum was sold for £ 4 10 s (equivalent to £ 406 in 2016 in modern money) per hundredweight (100-112 lb, 45-51 kg). [2] At Coldbath Fields PrisonThe men’s counterpart to Tothill Fields, prisoners had to pick 2 lb. (0.91 kg) per day unless they were hard to work, in which case they had to pick between 3 and 6 lb. (1.4 and 2.7 kg) of oakum per day. [3]


Oakum can be used to seal cast iron pipe drains. After setting the pipes together, workers pack oakum into the joints, then pour molten lead into the seal to create a permanent seal. The oakum swells and seals the joint, the “tar” in the oakum prevents rot, and the lead keeps the joint tight. Today, modern methods, such as rubber seals (for example, gaskets or o-rings ) are more common. [4]


In Herman Melville’s novella Benito Cereno , crew members of a slave ship spend their idle hours picking oakum.

Charles Dickens’s novel Oliver Twist mentions the extraction of oaks by orphaned children in the workhouse. The oakum extracted for use on navy ships, and the instructor said that they were serving the country.

The Innocents Abroad , a travel book by Mark Twain , aussi references in chapter 37 a “Baker’s Boy / Famine Breeder” who eats soap and oakum, order Prefers oakum, qui Makes His foul breath and teeth stuck up with tar.

We love the tarry rope to shred
With blunt and bleeding nails;
We rubbed the doors, and scrubbed the floors,
And cleaned the shining rails:
And, rank by rank, we are planked,
and clattered with the pails.

-  Oscar Wilde , The Ballad of Reading Gaol , 1897


  1. ^ Jump up to:b Kemp, Peter (1979). The Oxford Companion to Ships & the Sea . Oxford University Press. p. 807. ISBN  978-0-586-08308-6 .
  2. ^ Jump up to:c Mayhew, Henry; Binny, John (1862). The Criminal Prisons of London, and Scenes of Prison Life . Volume 3 of The Great Metropolis. London: Griffin, Bohn, and Company. p. 477.
  3. Jump up^ Mayhew & Binny (1862) p. 312.
  4. Jump up^ Yates, David (1 February 2005). “The Lost Art of Making Lead Joints” . Contractormag.com . Retrieved 6 July 2011 .