This guide mostly concerns itself with natural rubber – usually called "latex" – a polymer that occurs naturally in the sap of the rubber tree. The chemical name for natural rubber is polyisoprene.
Natural rubber is very stretchy, and available in many different colours. In the form of sheet latex, it usually has one smooth and shiny side, and one less smooth side. This is a result of the manufacturing process.
Natural rubber is resistant to many chemicals; notable exceptions are vegetable and mineral oils (other than silicone oil), which will degrade it quickly, and some metals (iron, copper, manganese, and cobalt) which can discolour rubber and degrade it in the long term. Natural rubber is also susceptible to degradation through sunlight; raw surfaces can develop a white coating (usually preventable via a thin layer of silicone polish) or become dry and crack.
Neoprene or polychloroprene is a synthetic rubber. It is most commonly used as foam sheets (in clothing, wetsuits etc.) or as a main component of contact glue (see Glues.)
Neoprene has better chemical stability than natural rubber and is resistant to most oils and metals.