Oakum

Key takeaways

Oakum belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Oakum to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Oakum from memory before moving on to harder problems.

Reference excerpt

Oakum is a preparation of tarred fibers used to seal gaps. Its traditional application was in shipbuilding for caulking or packing the joints of timbers in wooden vessels and the deck planking of iron and steel ships. Oakum was also used in plumbing for sealing joints in cast iron pipe, and in log cabins for chinking. In shipbuilding it was forced into the seams using a hammer and a caulking iron, then sealed into place with hot pitch. 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.

Plumbing 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 joint to create a permanent "lead and oakum" seal. The oakum swells and seals the joint, the tar in the oakum prevents rot, and the lead keeps the joint physically tight. Oakum present in older cast iron bell/spigot joints may also contain asbestos, requiring special methods for removal. Today, modern methods, such as rubber seals (for example, gaskets or o-rings), are more common.

Cultural references 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 oakum by orphaned children in the workhouse. The oakum extracted is for use on navy ships, and the instructor says that the children are serving the country. The Innocents Abroad, a travel book by Mark Twain, also mentions in chapter 37 a "Baker's Boy/Famine Breeder" who eats soap and oakum, but prefers oakum, which makes his breath foul and teeth stuck up with tar.

Jack London, in his book The People of the Abyss (1903), mentions picking oakum in the workhouses of London. Robert Jordan, in Winter's Heart alludes to picking oakum as a punishment among the Sea Folk. Joshua Slocum in Sailing Alone Around the World, describes caulking his ship the Spray, with oakum. Guy de Chauliac in The Major Surgery of Guy de Chauliac, frequently cites oakum as a medical supply in his treatments of wounds. Bernard Cornwell, in his Sharpe novels, refers to Richard Sharpe's childhood in a workhouse, picking fibres from old rope.

References

Illustrations

Worked examples

Example 1 — a first encounter with Oakum

Start with the simplest possible case. Write down what Oakum claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Oakum before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Oakum ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Oakum

In research: Oakum appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses Oakum in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: Oakum is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hemp products, Jute, Shipbuilding, so understanding it makes those chapters shorter.
In everyday life: Look for Oakum outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

How to study Oakum in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Oakum means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain Oakum out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Oakum in simple terms?

Oakum is a preparation of tarred fibers used to seal gaps. Its traditional application was in shipbuilding for caulking or packing the joints of timbers in wooden vessels and the deck planking of iron and steel ships.

Why does Oakum matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Oakum?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Oakum.