Technical Details: Ceramic Material.
The material I use for slip-casting is the result of 30 years experimenting although based on published recipes. The greatest proportion is white earthenware clay, sold in solid de-aired blocks. This is a commercial product which I think of as plastic clay, because I also incorporate additional china clay, quartz and feldspar in powder form. This way, I have reduced the plasticity of the clay but increased the whiteness and heat-tolerance of the material which could now be regarded as semi-porcelain. The powder and plastic clay are mixed together with water and deflocculant into a runny liquid which will fall through an 80’s mesh sieve held in a vibrating oscillator.
It weighs in at about 34 to 35 ounces by weight to one pint by volume. If you wish for an accurate recipe, please send a SAE or ask for it by email.

This liquid slip is poured into dry plaster-of-paris moulds. I call them ‘multi-part moulds’ because many potteries use plaster moulds, but I have never seen more than three or perhaps four parts used by a commercial concern. They make their working moulds in dense plaster or perhaps silicone rubber ‘case’ moulds because they need the repeatability and interchangeability of parts that comes from identical moulds. Figurines may be cast in several sections, for instance, legs, arms, heads, and reassembled while stiff enough to handle. I designed my horse and dog models to be cast as one whole body including the legs and head. The only part cast separately was the tail moulding, which was frequently used to conceal the filling and emptying hole. This means that a typical mould for a standing dog or horse model will have nine to ten parts, plus two for the tail. I have found that this is the better procedure. It means a longer and more complicated job mould-making but easier fettling. I also feel the structure of a large animal on four thin legs is stronger because there are no weak joints.

This approach could not be used for the Van-Dal little girl or the Van-Dal Cat in the shoe. The little girl was cast as a body (torso and arms, down to the hem of the skirt), legs with a flat upper platform on which the torso rested, a left ankle and foot in the left shoe and the same for the right foot and shoe, with a small additional part being the bow on the head. All the parts were cast in batches of ten, trimmed of the waste clay and usually rested in an old fridge which we used as an air-tight damp cabinet. The plinth had to be supported underneath with a cup shaped insert, because otherwise we found the weight of the girl caused the top of the plinth to cave down. Remember, this material is fired to 1140 degrees centigrade, a fierce yellow/orange heat, and very close to melting point.

Method of assembly: The cup was inserted into the plinth. The large holes were to let the air out as it dried, and out and in during firing. There was also a relief hole in the torso. The shoes were attached to the legs and then the shoes to the plinth. This assembly was then rested in the damp cabinet until the slurry used as glue had stiffened. Only when this sub-assembly was firm was the fettled torso, with its bow already attached, placed on top. The completed model was then rested again. Models were air dried and then fired 13 in a round 3 cubic-foot top-loading kiln, all heads facing inwards and touching so that they supported each other during the biscuit firing. They were then sprayed with a pale cream/white/transparent gloss glaze and fired again, 12 to a kiln, not touching. The glazed models were then hand-painted with enamel bright gold on the hair ribbon and gold shoes. The gold lettering was on a water-slide transfer, printed by a local firm. The models were then fired for a third time at 750 deg. centigrade to fuse the 22 carat gold to the glaze. The base also shows the incised lettering, the logo, AF, and the year date, M = 1981.

The Van-Dal cat gave us another technical problem because the Siamese (seal-point) cat had to be coloured to breed standards, but the brown must not be allowed to discolour the grey shoe. It was designed so that the oval plinth was cast, fettled, sprayed with a white/cream/transparent gloss glaze and once-fired. The shoe was cast, fettled, and sprayed with a satin grey glaze. The cat’s body, legs, and the cushion she rested on were cast in a two part mould, and the head and ears in a separate three part mould. The head was attached to the body, and allowed to dry. The body was air-brushed with a warm cream colour and the seal-points were air-brushed with a dark brown. The red cushion was hand-painted with the same maroon red colour as the transfer printing, and the whole cat sprayed with a satin glaze. Then the assembly was inserted into the grey shoe. The whole was then once-fired and the glaze on the underside of the cat fused her to the shoe. After this firing, the transfers were applied to both sides of the plinth and fired again. Finally, the fired shoe was attached to the fired plinth and a leather insole (provided by Van-Dal) inserted to cover up the void in the high heel. It was important to the client that the look of contentment on the cat’s face, the seaming on heel and instep, and the welts of the sole and heel were sharp. The four moulds (a total of nine parts) were not allowed to wear too much before being replaced. It was fortunate for us that a nearby farmer required waste plaster to harden the entrance of a previously muddy field.

Van-Dal cat in the shoe, port side view.	Base of the piece, showing the incised letters, Lenham Pottery Norwich, the logo, AF, and the year date: R = 1986.

The Start-Rite Shoe was made in 1991 for their Bicentenary Year, 1992. One shoe was presented to Prince Charles, 24th January, 1992. Another went to Norwich Museums Service to join the Van-Dal little girl and the Van-Dal cat on display in the Norwich shoe industry collection in the Bridewell. The only problem we had with this model was the number required (1500) while still producing our normal amount of dolls house china and horses. In this one instance I resorted to making silicone-rubber case moulds from which I could cast working pottery-plaster three-part moulds. It was important to Start-rite that the details of stitching and pattern on the sole remained sharp. This meant that we could not work the moulds as frequently as we might normally do, and had to replace them as soon as these details showed signs of wear.

A gold enamelled version of the shoe for very special presentation purposes.

A black version of the shoe for Directors, with the presentation box.

The black version, shown right, was easier to do than the gold version above, because it was black all over, only the sole being wiped clear of glaze lest it should stick to the shelf in the kiln. Painting the gold, which comes out of the bottle a very dark brown, onto the black glaze was difficult because we could not see errors until after firing. The gold shoe had to be white inside, but smudges of the dark brown unfired enamel could be wiped off.

During the summer holidays, when I had student workers to help, we had twenty sets of working moulds on the table, with each mould being used twice a day for five days and then dried over the weekend, or until the back-log of fettling was cleared. The casts were easy to handle, and were once-fired with a white gloss glaze at 1140 deg. centigrade. The welts and buttons were hand-painted with 22 carat gold enamel and the water-slide transfer placed inside before being fired again at 750 deg. centigrade. With these large-volume commissions I had to employ extra workers. Family, students, and extra part-time ladies helped me achieve the target in time. By this time I had a 400 sq. ft. new sectional workshop in the garden with three kilns as well the previous workshop, a long 160 sq ft conservatory attached to the house, now used as a design studio and plaster-casting workshop.

BRONZES: Lost wax which is liquid hot metal castings into refractory moulds.

With the development of affordable silicone rubber (two part, room temperature vulcanising) for master moulds, I was able to encase my original clay model in a flexible silicone rubber mould. This enabled me to use the rubber mould to make a rubber original to keep without fear of damage in the subsequent plaster mould-making. It also enable me to make wax models and try my hand at lost wax casting.

Into the rubber mould, I poured liquid hot wax. Before it solidified, the excess was poured out to give me a hollow wax model. To this model, runners and risers in wax were attached. The wax was filled with refractory plaster and also submerged in a steel can filled with refractory plaster. Then the wax was melted out in the kiln and the plaster fired to eliminate all organic material. Whilst still hot, yellow-hot liquid bronze was poured into the dog or cat-shaped hole in the plaster. Our first furnace was a small brick-built firebox heated by burning coke with a forced-draught from a reversed vacuum cleaner fan. Only the crucible was professionally made. I began with small cats, particularly as the sitting domestic cat was technically easy to make and cast, with a nice big filling hole in the base which enabled me to get the internal core of waste plaster out easily.

This home-made method proved successful so that I had samples to show prospective clients. Several dog models were commissioned by breed clubs to serve as an unusual trophy. One model of the standing Keeshond was silver-plated over the bronze, mounted on a walnut plinth and I believe it went to a club in Scandinavia. Unfortunately, no photos of the dog bronzes survive. There are photos of the bronze cats and the bronze door knockers on the other media page. We replaced the original brick furnace with a purpose-made portable furnace, fired by bottled propane gas, but still using the vacuum cleaner fan for the air supply.

Extending the range from small dogs and cats, I made a model of a Yearling Race Horse, six inches high (twelfth scale), and the necessary rubber mould. This model was the largest that I could handle as the red-hot crucible had to be held at arm’s length when taken out of the furnace. The liquid metal then had to be poured into a small hole - the runner. When cold, the plaster was chipped and washed off. Most difficult of all was getting the unwanted plaster core out of the hollow body through a small hole in the tummy, which then had to be filled with a bronze peg and the patch disguised. The original model was a success but the edition of 9 was not completed. Commercial foundries could handle much larger crucibles and therefore their 1/6th scale horses looked worth the money they were charging. I very much regret that no photos were made at the time, and none have been found since.

A great many copies of the Animalier school of bronze horses were produced in the nineteenth century in France and even more have been made in filled resin since.

Filled Resin:
With flexible silicone rubber moulds, backed by rigid plaster outer moulds, it is possible to fill the moulds with casting resin. Adding metal powder to the liquid resin outer skin gives a result similar to hot-metal bronze. The way to tell is that metal is cold to the touch while resin, even if 75% metal, feels warm or air-temperature. If you see something advertised as “Cold Cast Bronze”, remember that it is glue with metal powder added. There is no strength to thin sections. Thin legs, such as those on my resin Dobermann model, on the page describing the other media, may have to have steel wires embedded in them to prevent breakage.

Fibre-glass and resin.
It is usual to place this material on the inside  of a mould, such as a boat hull. The making of the mould is incredibly expensive, and hundreds have to be cast from it to pay off these costs. However, by building up an armature of wire and aluminium mesh, it is possible to create a firm foundation onto which glass fibre may be laid and wetted with the liquid catalysed resin. Layers of resin and glass mat or tissue are built up to the required thickness. Additional surface modelling may be worked by thickening the resin with powder or other inert filler such as vermiculite or perlite, until it is as stiff as putty. In this way it is possible to create large hollow structures or free-form sculptures. The final finish may be metal-filled resin, coloured resin or in the case of the sea-horse, shown on the other media page, the finish is partly embedded fine granite grit over a dark green ground.