Vulcanised Rubber Sphere

This dark red, knobbly, bouncy toy ball is made of classic red natural rubber, the kind that is so dearly wished for in A.A. Milne’s poem “King John’s Christmas.” This material is made by refining latex, the milky sap produced by cutting the bark of tropical plants like the Para Rubber Tree, and the Rubber Fig. Latex is also produced by more familiar plants like lettuce and dandelions. While rubber had been used locally for many years, it was first commercially produced in France and England in the late 1700s, named for its ability to ‘rub out’ pencil and graphite marks on paper. It was also known as India Rubber, or China Rubber by the colonialists. 

Rubber is produced in industrial quantities today in South-East Asian tropical countries, but the latex is still tapped from trees in the traditional way. To make this ball durable and extra bouncy, the rubber is cured by the addition of sulphur, which is called vulcanisation (named after Vulcan, the Roman God of fire). The rubber, a natural polymer, then becomes an elastomer.