Enamelling on Copper
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Enamelling on Copper

Pat Johnson

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eBook - ePub

Enamelling on Copper

Pat Johnson

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About This Book

Copper enamelling - essentially, the melting of glass enamel grains onto a copper surface - is an exciting and fascinating technique. Enamelling on Copper highlights the unique interactions between copper and enamels, and gives a detailed account of working with this wonderful combination. The basic technique - simply sifting ground enamels onto a copper surface and firing the two in a kiln for one minute - is a thrilling experience, but delving deeper into the techniques pays even greater rewards. Starting with an introduction to enamels, this new book goes on to explain how to work with an enamelling kiln, including temperatures and timings; the different kinds of enamels and how they work together; the enamelling process and how to control small sifted particles of the glass enamels to achieve your designs. A final chapter is devoted to the practice of firing the enamels higher than is necessary in order to transform their colours to create unique effects.This book wiill be of great interest to all enamellers, jewellers and metal workers at all levels and is beautifully illustrated with 226 colour photographs.

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Chapter 1
Glass and Heat
1
WHAT IS ENAMELLING?
Enamelling is the technique of melting coloured glass particles onto a metal surface. The glass particles are known as enamels, the melting process is called firing and in this book, the metal involved is copper. An enamelled picture, bowl or piece of jewellery is often referred to simply as an enamel, the same word as the ground glass. The words ‘piece’ and ‘work’ relate to an object that is being and has been enamelled and the copper will be called either a ‘blank’ or a ‘panel’.
image
This piece of enamel, just a bit bigger than a golf ball, was broken off the cooled mass that had just come out of a crucible. The mass was roughly pounded until the pieces were small enough to be put in a mill and ground up into fine grains.
About enamels
Enamels are a type of glass made up of minute fragments of rocks and minerals, jostled together with a great deal of sand. When this mixture is put into a crucible and taken up to its melting temperature, the sand melts, and the elements and compounds in the rocks and minerals are released. In the matrix of melted glass they break apart and then, during the cooling process, join up to make new components. The separate particles are gone and in their place is an enamel, a glass that will melt at a specific temperature and that will adhere smoothly to certain metal surfaces. At this stage, the enamel is one large mass, soon to be broken up into pieces of pea-sized lumps or ground into grains.
Enamels come in a wide range of colours and works in enamel are created by applying layers of these colours one after another, with firings in a kiln in between each layer. A firing will melt the glass particles and produce a hard shiny surface.
ENAMEL BEHAVIOURS
Enamelling gold and silver jewellery and vessels is very difficult indeed. Not only are skills and physical effort required to form the metal, the colours of the enamel must be pure and lack surface blemishes. Perfection lies at the heart of this practice, requiring a great deal of time and patience. Precious metal enamellers work with pea-sized lumps, grinding them by hand in distilled water to prevent any kind of contamination. The enamels are applied to a silver or gold object using a brush or feather to put the damp grains in place. This technique requires great care. Once dried, the piece is fired for a short time until enamels melt, after which it is cooled slowly. The glass has become bonded to the metal but apart from this, nothing has happened to change the enamels’ structure and nothing is revealed about them except their wonderful colour.
Enamelling on copper is a different story. Here, the metalworking technique can be much easier but the actual roles of the enamels are more complex. Most importantly, the copper intermingles with the enamels and this has a profound effect on their colour. In addition, enamels fired on copper are treated in a very different way from those fired on silver or gold. They are sifted on rather than laid down wet and because it is hard to gauge exactly just how much enamel has been applied, the results are not entirely controllable. Unusual effects are regularly created and most of them are so beautiful and interesting that perfection is not required, although with practice and great skill in sifting, it can be achieved.
Copper is relatively inexpensive and the enameller is free to experiment. In particular, firing times and temperatures are allowed to vary from the norm. At higher temperatures the enamels interact with each other, resulting in new colours and textures that look like they were formed by an act of nature. Even heating an enamel to the point where its colour disappears is practised because nearly burnt enamel can be used artistically.
TRANSPARENT AND OPAQUE ENAMELS AND FLUX
Enamels come in two main categories – transparent and opaque. Transparent enamels act like watercolour paints in that any colour or drawing underneath will be visible but tinted with the colour of the paint or enamel on top.
Furthermore, the light colours must be applied first, because a dark colour underneath would not allow them to show up. Opaque enamels, on the other hand, behave like oil paint. Over layers of previously fired enamels, they will cover all the colours and designs that lie below them.
Most transparent enamels cannot be fired directly on to copper because the result will be a colour that is a combination of both. To allow the colour of the transparent enamel to show more clearly, a layer of colourless enamel, called a flux, must lie beneath it. The flux creates a space, which allows light to reflect back up from the surface of the copper through the transparent enamel, thus illuminating its colour. Some tinting from the copper remains, but it is much less pronounced.
There are many fluxes, all of which have different uses. Although supposedly colourless, fluxes actually appear to be lightly tinted when fired over copper. They can be transparent pink, gold, or a greyish blue. Transparent coloured enamels fired on top of a flux will be altered slightly, although much less than if they had been lying directly on the copper. The true colour of transparent enamels will only be revealed when they are fired over white opaque enamel.
image
This bowl shows several different enamels flowing and interacting with each other.
Nevertheless, regardless of the tinting effect, many pieces of enamelled copper feature a transparent on top of a flux because this is the way to make its thrilling colours glow.
Opaque enamels cannot produce the thrill of transparency but their strong colours play a major role in enamelling. They can be applied in any order of light and dark. The opaques often provide a wonderful foil for transparents but they are also the medium that will produce works of enamel that are on a par with fine art.
COMBINING ENAMELS
Almost all enamelling processes are based on layering. One layer is sifted on and fired, then a second, third and onwards, with trips to the kiln made between every application of enamel. When two enamels are fired at the same time, one on top of the other, a whole range of new possibilities opens up. A transparent red fired on top of a transparent yellow produces a wonderful orange, a colour that is difficult for enamel manufacturers to produce. Similarly, if a transparent red enamel is applied over an opaque yellow layer, the result will be an orange that simply has no equivalent in any other medium. Gradations of colour can be created, for example, with a layer of light turquoise blue on the bottom layer and a rich dark transparent blue lying over part of the turquoise, grading gently to produce a handsome, two-toned surface.
When enamels are melted together and fired above the recommended fusing temperature, a variety of reactions take place. Exploring these reactions, finding out how and when they occur, learning to control and use them to produce their wonderful new colours and textures is one of the pleasures that enamelling has to offer.
LEAD-BEARING AND LEAD-FREE ENAMELS
In addition to the categories of transparent and opaques, there is another area with two types of enamels – those that contain lead and those that don’t. Historically, all enamels were leaded but in the late twentieth century, the general concern over a number of potentially dangerous elements resulted in the development of lead-free enamels.
At the time of writing, both types of enamels are available. Each group can produce wonderful colours, so an enameller might choose a lead-bearing or lead-free enamel purely for aesthetic reasons. Using enamels from both groups together in one piece is possible, particularly if the lead-free enamel is fired on first.
How dangerous are lead-bearing enamels? Many enamellers who have been working with lead-bearing enamels for years have so far not suffered any ill effects. That said, it makes good sense to be careful. When enamelling regularly, a good-quality mask should be worn, no matter which kind of enamel is used and hands should be rinsed at the end of an enamelling session. In Chapter 2, there is information on how to find a mask that is effective.
Working with enamels
Making a work in enamel can be a quick process. Sifting on a colour takes no time and firings usually last one minute. Of course, the preparations may take much longer. Deciding on what is going to be made can keep the enameller occupied for quite a while and producing shapes and designs with enamel can be quick but also as long as a complicated drawing.
SIFTING ENAMELS
Most enamellers working with copper use pre-ground enamels, bought from companies that make and supply ground enamels. The most effective way of applying ground enamels is putting the grains of glass into a sieve and sifting them on to the copper surface. Sifting produces an even coating and allows for layering colours and covering large areas quickly. There are many ways of controlling where the enamel grains will fall and of using them to make any kind of image and design. Techniques for harnessing the potential of enamels as an art form are presented in Chapter 5 and onwards.
THE ACT OF FIRING
Physically, performing a firing is probably one of the easiest tasks in enamelling and it is the quintessential centre of the process. When one or more enamels resting on a piece of copper are put into a kiln, the conditions of the crucible are recreated in one minute. The grains of glass become liquid and blend into a whole.
For every enameller, firing is always exciting. The colour of the hot kiln chamber is wonderful and the sense of danger from being so close to the heat is compelling. The fired piece, fresh out of the kiln, is glowing orange, radiating a wonderful light that always leaves a sense of regret as it fades when the piece cools. It is only then that the colour of the enamel is revealed and the enameller learns if the firing has been successful or not. Often the result of the firing is what was wanted, but occasionally it is not. There might be disappointment or the enameller may receive a wonderful surprise.
Anyone who becomes involved with enamelling on copper must face the challenges of discovering the best firing temperatures and times for their enamels. Many factors are involved because each enamel is structurally unique, and overall there is a wide variety of firing behaviours. These will be discussed continually throughout the book but particularly in Chapter 4.
INTERACTING WITH ENAMELS
image
First attempts at enamelling are an opportunity to have an adventure, and to make a start in developing a personal relationship with enamel colours and techniques. After a while, a revelation occurs – that the whole process is two-way. The person enamelling has an idea in mind, a plan of action, and the enamels will have their own response to the plan. The finished piece, unless the enameller is very practised at reproducing what has gone before, is the result of a dialogue. Usually, it is lovelier and more exciting than the original plan.
Learning and inventing ways of manipulating the enamel grains so that they make textures, patterns, designs and pictures is a challenge. The enameller must also know what to do when things do not go to plan. Over the years, enamellers find out more and more about their art and craft. This progress is an amalgam of personal experience, learning from other enamellers, and reading about techniques. The varieties of enamel behaviour multiply out of sight but this is not a cause for despair. The pieces pictured at the headings of many of the chapters illustrate the rewards of learning to work with the fascinating combination of enamels, copper, heat and imagination. Success is a frequent occurrence; boredom is never a problem.
About enamellers
Enamelling is a very physical activity and personal experience is the best way of learning. Self-teaching will reveal the right amount of enamel to put in a sieve and how it feels when that right amount is subsequently sifted. What motion seems natural for dispersing ground enamel over a flat piece of copper or around the curved surface of a bowl? Chapter 5 suggests quantities and techniques that assist in answering this question, but eventually every enameller will develop an individual working practice. It all comes down to finding the movements of hands and arms that feel natural.
Because human physicality is involved, the result of any day’s enamelling is unpredictable. Judgements can vary wildly according to one’s mood. It is important to recognize that there are times when sifting will be too heavy or too light and estimations of firing times and temperatures are off the mark. Even if very careful notes are taken, and test pieces and samples are close at hand, reproducing a previous success is never guaranteed. The enameller should not take the blame if a piece does not turn out right – unknown factors due to the interactions of the enamels...

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