In memory of Bill Helwig, the distinguished American enameller who died this summer, we reprint a shortened account of the Master Class he gave at our 1993 conference.

“The most important thing to remember is that enamel is glass and glass is a liquid. It melts and floats and is only rigid when it is super cooled. Therefore the most dangerous thing you can do is add another liquid like water. Bill preferred to avoid using water as much as possible although this did not apply to preparing enamels for jewellery, where, to obtain absolute clarity for such fine work, enamel had to be ground in water.

A lump of enamel decomposes rapidly and even more rapidly in powder form: and some colours decompose quicker than others; greys, for instance, decompose within 2 hours! 1400-1500th C enamellers ground their enamels in the morning and then re-smelted them back into lump form at the end of the day. Cellini described how to chew up paper to make a wad to dry out water from his work, so it was known then that enamels would decompose more rapidly when in contact with another liquid.