Pitch (resin)

Pitch is a viscoelastic polymer which can be natural or manufactured, derived from petroleum, coal tar,[1] or plants.

Other important historic uses included coating earthenware vessels for the preservation of wine, waterproofing wooden containers, and making torches.

[4] The viscoelastic properties of pitch make it well suited for the polishing of high-quality optical lenses and mirrors.

The ability of pitch to flow, albeit slowly, keeps it in constant uniform contact with the optical surface.

This means that even though it seems to be solid at room temperature and can be shattered with a hard impact, it is actually fluid and will flow over time, but extremely slowly.

[6] Another experiment was started by a colleague of Nobel Prize winner Ernest Walton in the physics department of Trinity College in Ireland in 1944.

The Jewish deuterocanonical Book of Sirach states that "whoever touches pitch gets dirty, and whoever associates with a proud person becomes like him".