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.
Forge
A "slack tub" is usually a large container full of water used by a blacksmith to quench hot metal. The slack tub is principally used to cool parts of the work during forging (to protect them, or keep the metal in one area from "spreading" from, for example, nearby hammer blows); to harden the steel; to tend a coal or charcoal forge; and simply to cool the work quickly for easy inspection. In blade smithing and tool making the term will usually be changed to a "quench tank" because oil or brine is used to cool the metal. The term slack is believed to derive from the word "slake", as in slaking the heat.