Oakum
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 seal. The oakum swells and seals the joint, the "tar" in the oakum prevents rot, and the lead keeps the joint physically tight.
Today, modern methods, such as rubber seals (for example, gaskets or o-rings) are more common.
Tar
In Northern Europe, the word "tar" refers primarily to a substance that is derived from the wood and roots of pine. In earlier times it was often used as a water repellent coating for boats, ships, and roofs. It is still used as an additive in the flavoring of candy, alcohol, and other foods. Wood tar is microbicidal. Producing tar from wood was known in ancient Greece and has probably been used in Scandinavia since the Iron Age. For centuries, dating back at least to the 14th century, tar was among Sweden's most important exports. Sweden exported 13,000 barrels of tar in 1615 and 227,000 barrels in the peak year of 1863. Production nearly stopped in the early 20th century, when other chemicals replaced tar, and wooden ships were replaced by steel ships. Traditional wooden boats are still sometimes tarred.