In 1839 Charles Goodyear discovered the method of mixing sulphur with rubber to form hardened or vulcanised rubber, called Vulcanite. The proportion of sulphur can be increased or decreased in order to vary the required amount of hardening accordingly. Between 25-50% sulphur gives a hard product with the familiar feel of plastic. There are many Victorian vulcanite objects, but the most common form is an imitation of Whitby jet used widely in the production of brooches, bracelets and necklaces. Vulcanite could be produced in almost any colour, although the predominant colours are black (ebonite) and brown. As a result, vulcanite was by far the most widely-produced Whitby jet simulant. Unlike pressed horn a thermoplastic materials which, if heated again can be re-moulded into a different shape. Vulcanite is a thermoset material which, after moulding becomes brittle and cannot be remoulded.  Vulcanite can be distinguished from jet relatively easily. If the material has been exposed to light over time it loses its black colour and becomes khaki brown. When rubbed, vulcanite smells strongly of sulphur and brooch pins are usually screwed into position rather than glued. Chain links only show one or two splits depending on the link style as the link can be twisted open and then closed. In comparison in Whitby jet links, where every other link in the chain is cut and glued and will always show two or three cuts depending on the style of link. As vulcanite pieces were often moulded from jet originals the same design is seen regularly and, with experience, can be identified easily. (Please note: the ‘streak’ test on vulcanite will reveal a light brown streak similar to that of hard Whitby jet and so should not be relied on).

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