Colouring clay in the UK
The closest the United Kingdom ever came to a coloured clay tradition took place in the county of Staffordshire during the eighteenth century. At this time the British Empire was developing and the mercantile classes were prospering with the burgeoning industrial revolution which included many advances in pottery technology. Business orders from abroad gave the potters in the towns around Stoke in Staffordshire room to be inventive with the pottery they produced. Perhaps inspired by imported Chinese pottery which used coloured clays, local 'Agate' ware was produced, possibly as early as 1700 and continuing at least until 1750.
Crucially the manufacturers of this new style chose not to use stoneware, instead opting for earthenware clays and low fire transparent lead glazes. It must have been apparent to local potters who wished to pursue the idea of colouring clay that a pragmatic approach was necessary and that it would be sensible to stick with relatively manageable temperatures while experimenting with a new technique.
The same cannot be said of JW who was driven by the idea of making fine ceramics and prepared 10,000 tests in order to fufill his goal. He kept the results of his experiments secret, writing his notes in code. This code has subsequently been broken and his various clay body formulas and recipes are now known to all. His interest in producing good quality ceramics was galvanized at the time by excavations of Roman vases in Italy in 1769. The impression given is that he was struck by the fantastic craftmanship of the Italian work and somehow wanted to duplicate it for the masses. His inumerable tests led to Jasperware being patented in 1771.This was an unglazed ceramic ware that borrowed on the style of marble vases and urns from antiquity. The design element of this work also relied on the contrast between the different coloured clay bodies that composed the work.
Josiah Wedgwood became an industrialist, a highly motivated man in the right place at the right time. His fabulous connections helped build his reputation. By 1790 he was selling his ceramics to every city in Europe.
Now in 2018 there is little evidence of coloured clay ceramics in the UK.
North America has some fine and successful practitioners, notably Thomas Hoadley and Curtis Benzle.
In Japan staining clays to produce handbuilt ceramics is recognised as Nerikomi but in Europe, the technique is rarely practised which is suprising given the scope for design possibilities within this technique.
The modern age has provided an enormous range of ceramic pigments that were unavailable 20 years ago, this, with the availability of very white porcelains means we can produce vibrantly coloured clay.
If we go through the process, it may become clear why colouring clay is considered to be a niche technique.
Mixing body stains with porcelain creates a short clay, quite unmanageable and prone to cracking. This is especially true of the extra fine particled whiter porcelains that do not need the addition of even finer particles. This kind of clay will provide heartache to the potter but problems in the studio can normally be overcome.
The answer to creating a malleable clay can be found in many English kitchens. Treating your porcelain to Lyles Golden Syrup will loosen the clay and reduce the likelihood of tearing around the edges of slabs etc. The sugar has the effect of binding clay particles. A by-product of this is less dust. Helping the performance of the clay body will not ensure the work will survive bearing in mind the extraordinary contraction rate of very white porcelain (15%) although steps can be taken to aid survival
It is essential to let your work dry slowly and in the pots own time. Let the pot sweat out the moisture, molecule by molecule. This can take weeks, even months. Drying pots can be done by wrapping the work in fine polythene (obtained from dry cleaners). After three days, look closely for condensation on the interior of the plastic which will come in the form of beads of moisture. Remove and reverse the polythene, keeping this up until the moisture disappears. Enormous patience is necessary at this stage, the temptation might be to speed things up but if you are not playing with fire yet, you will be when it comes time to put the pot in the kiln.
The final firing will take on some significance as it has taken so long to get to this point. Once again, there is a proceedure that can help the delicate nature of the clay body. It will involve making an open saggar and filling it with alumina bubbles. These are very small, hollow, thin walled alumina spheres made from fusing high purity special alumina. The melt is atomized with compressed air producing cute little low density bubbles. Immersing your piece of work in them will dampen any thermal shock and allow you to ratchet the temperature up and obtain a 1250 degree centigrade firing, a temperature the porcelain will appreciate
The key to making contemporary coloured clay ceramics are the stains available nowadays.
Body stains currently on the market can be a useful tool, offering tremendous scope for contrast and invention. I am sure Josiah Wedgwood would have looked on in envy.