One of the most significant processes that is still widely in use today is slip casting. Although simple in concept, to be used successfully and to its full potential, it requires a wide variety of skills and an in-depth understanding of the materials it draws upon. This process allows highly decorative shapes to be made that would be impossible to make economically by hand in any large numbers.
Limoges is famous for its ceramics, and two major manufacturers still based there, Bernadeau and Royal Limoges. They have set up in their original 18th century premises displays that document their histories and the manufacturing processes they used, and still use, albeit now in the industrial outskirts.
First we visited Bernardaud (http://www.bernardaud.fr) which has immaculately restored and presented buildings, a short walk from the center of the City. There is a small very upmarket showroom of their most recent and expensive products, and a helpful assistant who took some time talking us through the various pieces on display, classic designs and more recent ‘designer’ contributions. The work is beautifully made, and one or two pieces were lovely designs; unfortunately they do not allow photographs so that goes undocumented! I imagine that for a majority, the prices are prohibitive, including us, so we were shown next door to the outlet shop while we waited for the guided tour…some bargains to be had!
The tour is comprehensive, although delivered at pace in French. If you were not familiar with the topics you might struggle with the detail, but the examples are well presented and are generally self-explanatory.
The process is at once simple and challenging. Faithfully reproducing complex designs requires an intimate understanding of mould making and the ability to design moulds in such a way that the cast objects come out intact and requiring as little fettling (cleaning up) as possible.
Work stations with over head racks of drying casts, waiting to be fettled
The original, be that a mug, bowl or figurine, is created and used to make a plaster mould. A simple thing such as a bowl, with no undercuts that would prevent it being lifted out of the mould, could be made from a single-piece mould, but for objects with undercuts there may be three or more mould segments. By carefully designing the moulds, the parting line (the seam where the mould parts meet) is placed where its visual impact will be minimised. This is important because as little cleaning up as possible is desirable, not only to maintain the integrity of the design, but to keep the cost down. The design of the object and how it will be made have to be considered hand in hand.
The mould pieces are strapped firmly together and a viscous solution of clay (slip) is poured into the mould and left to stand; the length of time depends on how thick the wall of the object needs to be. The mould is drained, leaving a layer attached to the inside of the plaster mould. As moisture is absorbed into the plaster, the clay dries, shrinks slightly and can then be removed, very carefully, from the disassembled mould. The casting is allowed to stand, and when firm enough to safely handle, the part lines are gently removed. From there the process becomes more familiar- bisque firing, glazing and final firing again.
Royal Limoges, the original buildings
Before the introduction of this process, potters were essentially restricted to three ways of making pots- construction, forming and throwing. The latter, being the most common and efficient method, has the disadvantage of producing only round symmetrical shapes unless further hand work is used afterwards. The dramatic and game-changing aspect of slip casting is that within reason, more or less any shape can be made, shapes that have little to do with traditional thrown pots.