Technical Information

Placing a piece of metal in the kiln covered in a powder which can sometimes bear no resemblance to the finished colour of the enamel and to see it come out, glowing, red hot, then to watch it cool and change colour is a magical, exciting and very satisfying process and one which has been practised for hundreds of years.

Basically enamelling is the art of fusing glass onto metal. Many different metals can be used for enamelling, but the most frequently used are copper, silver, gold, iron and steel and more recently Precious Metal Clay (PMC).

Enamel is a clear flux or frit and is made up of materials such as lead, potash, flint and sand which is then coloured by the addition of oxides which help create all the various colours found in enamels today.

Enamel can be clear, transparent, opaque or opalescent. It can be leaded or lead free, ground from glass lumps into powder, used in liquid form or ground very finely, mixed with oils and used in the same way as paint, it can be used as fine lumps, glass rod or millefiori. It can be purchased in various mesh sizes, 80 mesh being the one more readily available commercially with a texture similar to sugar; finer mesh sizes are also available such as 100, 150, 200 and 350.

Opaque enamel will block out whatever is beneath it and the final result will be no different whichever base metal is used or whether other enamel colours have already been applied.

Transparent enamel can either be clear or coloured. They allow light and colour to pass through to the metallic surface on which they are laid. Using transparent enamel on silver can create vibrantly stunning colours.

Opalescent enamel is a translucent glass that is not completely clear, it has a milky appearance and is similar to that of an opal, hence its name.

The properties of enamels are varied, they have diverse compositions so that they adhere or bond to metals in different ways depending on their softening and flow points. Enamel does not melt, it softens and flows, some enamels may soften at the same temperature but may not flow or smooth out at the same rate as each other so each and every enamel used should be tested first on a small piece of the base metal being used (aprox 1cm2) to see how it reacts. All colours react differently and only experience can help you determine which one to use. A collection of these test pieces documented to show results over various layers of enamel, different types of flux, and different melting points etc is invaluable and can be referred to time and time again.

If enamel is applied to one side of the metal only the resulting tension can cause the metal to ‘ping’ off and so a counter-enamel is applied to redress the tensions. However, the need for counter-enamelling is also dependent on the thickness of the metal being used and the number of layers of enamel being applied, the thicker the metal or the fewer layers of enamel used then a counter-enamel may not always be necessary.

Today we are very fortunate that we are able to buy our enamels ready made. In his treatise ‘On Divers Arts’ the following excerpt by Theophilus Presbyter, a 12th century German monk describes how to prepare and test enamels

"………… take all the kinds of glass you have prepared for this work and breaking off a little from each piece put all fragments at the same time on a single sheet of copper, each fragment, however, by itself. Then put into the fire and build up coals around and above it. Then while you are blowing observe carefully whether the fragments melt evenly; of so, use them all; but if any fragment is more resistant, lay aside by itself the stock that it represents. Now take all the pieces of tested glass and put them one at a time in the fire and when each one becomes red hot throw it into a copper pot containing water, and it will immediately burst into tiny fragments. Quickly crush these fragments with a pestle until they are fine. Wash them and put them into a clean shell and cover with a linen cloth. Prepare each colour separately in this way…………"

As you can see there are many variables to take into account when enamelling in addition to the skill required to make the artefact or piece of jewellery to be enamelled in the first place.

Lead free enamels are safer to use and more acid resistant than leaded, but both are hazardous to health if inhaled and a facemask, approved for protection from fine toxic dusts, should be worn when using enamels. Many enamels contain toxic ingredients such as cobalt, chrome, cadmium and selenium, which are all known carcinogens, so it also makes sense not to eat or drink in the enamelling studio and to make sure the area is well ventilated.