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.
Zipper
This double-mated surface is good at retaining both vacuum and pressure, but the fit must be very tight, to press the surfaces together firmly. Consequently, these zippers are typically very stiff when zipped shut and have minimal flex or stretch. They are hard to open and close because the zipper anvil must bend apart teeth that are being held under tension. They can also be derailed (and damage the sealing surfaces) if the teeth are misaligned while straining to pull the zipper shut.