Vulcanised rubber is the stuff of car tyres, industrial valves and traditional wellington boots. It is tough, elastic, waterproof, resistant to solvents and impervious to moderate heat and cold. However, these properties do not come naturally. ‘Natural’, or uncured latex rubber is the sap from various types of rubber tree. In this state the rubber is very elastic, but will not last. Over time it will dry out, crack and crumble as it decomposes.
The process of vulcanisation was discovered by Charles Goodyear (oddly, no relation to Goodyear tyre manufacturers) and was arguably one of the most important industrial discoveries of the age. Liquid rubber has sulphur added to it, then through a combination of heat and pressure, the inner structure of the rubber changes, making it far stronger and more durable. Named ‘vulcanization’ after the Roman god of fire, this heat process allows the long chains of molecules in the material to bond together, becoming more like a 3D fishing net, geometrically spaced, strong, resilient and elastic in any direction.
This black rubber cube has some other ingredients to make it even tougher and abrasion-resistant. Carbon black is used as a pigment and reinforcement, and is made by burning old tyres.