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.
Worm, parcel and serve
The tar, or "slush" is a mixture of Stockholm tar, boiled linseed oil, and Japan drier. Many "recipes" for slush exist, but the intent is always to allow a penetrating coat of preservative pine tar that then cures to a harder finish that will not so easily rub off on sails and crew. The term "slush" is also used to describe the grease applied to the masts to lubricate the parrels so that the yards can raise and lower freely.