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A slip-cast object is a satisfying thing. It is the reward of all the investment of time making the model and molds.

Slip casting step by step

FORMING TECHNIQUES // SLIP CASTING STEP BY STEP

2| Fill a plastic jug with slip. For large molds, have a couple of jugs of slip

on standby so a continuous pour can be maintained. Pour the slip carefully into the mold. Aim for the center and not the sides. Pouring too fast can cause casting spots or swirl marks. Pouring too slowly risks fi lling lines or causing variations in thickness. Fill the mold and keep topping up the slip reservoir.

1| Prepare the slip by mixing in a blunger or with a handheld blender.

Ensure the mold is completely dry and place a tight rubber band or cord around the outside. This will prevent the mold from opening once it is full of slip. If your mold does not have a spare (see p. 93), place a coil of clay around the top of the mold to create a slip reservoir.

3| Casting times vary on the type of slip, size of mold, and consistency of

slip. Allow approximately 20 minutes for an earthenware and semi-porcelain body. Bone china and porcelain take much less time, approximately three minutes. After this time, the slip can be tipped out. This should be done steadily—not too slowly, as this can cause draining marks, and not too fast because this can create a suction that can pull the cast away from the mold. If you hear a glugging sound, tip back the mold slightly and ease the fl ow.

4| Place two wooden sticks of uneven height on top of a container. The

uneven height is important because this allows the slip to run down the sides and prevents stalactite droplets from forming in the base. Turn your mold upside down and place on the sticks. Leave to drain; do not reverse the mold too soon as this can cause wet areas to run back; the cast should have a matt, waxy sheen.

6| Empty the mold after 30 minutes to 1 hour. Discard your fi rst cast as

this may be contaminated with plaster. 5| Once the cast is touch-dry and has

a matt sheen, trim away the spare with a sharp scalpel. A blunt knife will cause the cast to crack. Be careful not to cut or scratch the mold. Tidy and sponge the rim.

7| When the cast has dried to leather-hard or green state, remove seam

lines with a sharp knife or scalpel (this is known as fettling) and sponge the area. Handle the piece as little as possible.

Techniques to try Casting slip can be colored with the addition of 10% stain to 2 pints (1 liter) of slip. Try experimenting with painting or slip trailing colored slip inside the mold before fi lling the mold with white slip.

The fi nished cast will appear to have a fl ush decoration in the surface.

To emboss the cast, lightly scratch into the plaster mold and brush away any loose bits of plaster. Secure the mold and fi ll with slip.

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Gallery: slip casting and molds

FORMING TECHNIQUES // GALLERY: SLIP CASTING AND MOLDS

Christie Brown (UK) Entre Chien et Loup, 2003/4 Each fi gure H: 51in (129cm), W: 10in (25cm), D: 10in (25cm) Ceramics and mixed media Brown’s work encapsulates an ongoing interest in multiples, repetition, and the metaphors associated with molds.

Sasha Wardell (UK) Large Shoal Vase, 2008/10 H: 15in (38cm)Slip-cast bone china, layered and incised with colored/stained casting slips

Maria Lintott (UK)Bloom Jugs, 2009H: 3in (8cm), Dia: approx. 3½in (8.5cm) Slip-cast fi ne bone china with hand-applied fl oral sprigs

James Rigler (UK)Valley, 2007

Approx. 9ft 10in (3m) by 6ft 6in (2m)Glazed earthenware;

press-molded ceramic; plaster molds taken from sledged/lathed/

assembled plaster models, then press-molded, bisqued, and glazed The layout of the elements means

the piece can vary in size and shape to interact with its site.

Ruth Borgenicht (USA)Gray Moon, 2008

H: 15in (38cm), W: 13in (33cm), D: 5in (12.5cm)

Stoneware; slip-cast, unglazed, colored casting slip; fi red to 2372°F

(1300°C/cone 10) This artist uses the chain-mail

pattern and other woven patterns to create ceramic works that

conjure up a sense of permanence and defensive concealment.