By Raymond Jackson

Introduction

As a relative beginner in the craft of enamelling, I find myself especially attracted by transparent enamels. They yield their true beauty when light is reflected through them from the metal substrate beneath.

Copper, being much cheaper than silver, is a popular metal base for enamelling. However, the copper oxides that form at the high kiln temperatures necessary to fuse the enamel to the metal can both colour the enamel and reduce the transmission of reflected light. Some transparent enamels are little affected but most appear somewhat opaque and dark. As a consequence it is generally good practice to first apply a colourless enamel flux. This flux is formulated to more easily absorb the copper oxide. The result should be a clear and bright surface onto which coloured transparent enamels can then be applied.

The proper application of enamel flux is thus an important first step in achieving reflective enamel pieces with copper as the base metal. In contrast, silver presents problems only for specific enamels (eg some reds and oranges) and the flux layer is correspondingly less necessary.

Through my inexperience and understanding of the factors involved in achieving transparency with enamel flux, my enamelled pieces were rarely clear or bright, and more often they were muddy, or cloudy.

I decided, therefore, to embark on a series of experiments aimed at finding and controlling the factors that determine the clarity of enamel flux applied to copper. These experiments deal with the sieving of dry enamel flux powder on copper. Most of the results, however, are also relevant to the technique of wet laying of enamel flux.

This report describes those experiments that have subsequently led me to achieve a consistent and acceptable enamel flux base coat.

The information is presented in the hope that other beginners may find it useful. It owes much to various excellent publications that provide background information on the fluxing of copper.

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