In 1712 John O’Bisset discovered horn could with the application of heat, be moulded into various shapes. When cooled the shape was retained – O’Bisset had discovered the first natural thermoplastic material. Sheets of horn were put between hot metal plates in a press and pressure applied. Placing the warmed horn into moulds before applying pressure enabled the production of horn boxes, beakers and other items. With the application of black dye, pressed horn was a good candidate for a simulant of Whitby jet and many jewellery items were produced.  Horn has a tendency to delaminate due to its layered structure, so loupe examination often reveals these layers, especially on the reverse of brooches. Any damage to the edges also gives a slight transparency to the damaged area, which is not seen in Whitby jet. The colour can often seem uneven and it is not possible to screw a brooch fitting into jet. Therefore a screw, often seen in horn, is always a sign of a simulant. 

All search results