Instruction for Ceramic Sculpture

Five stages of clay

Beside the usual state of wetness out of the bag, there are 5 consistencies of clay, each with a different colouring:

1. wet from the bag
2. ”leather hard”: dried by leaving the sculpture uncovered for a while
3. completely dry but “green” (=unfired), If you carve dry clay, beware of the dust, which is a health hazard and use a dust mask. When sculpting at this late stage, dampen and score the sculpture up to 3 mm depth ,: you can dow both add clay in thin layers, and carve the sculpture using a metal scraping tool
4. biscuit fired (only up to 1000C),
5. fully fired (depending on clay, up to 1250C)

Most sculpting happens at stage 1 and 2; though at stage 3 it can still be carved and sanded down like a soft stone; adding clay is possible (see “Repairs”), but challenging; Glazing or addition of oxides happens either at stage 3 or 4. A fully fired sculpture at stage 5 is “vitrified”, which means it is as hard and impermeable as glass, and can survive frost outdoors

Modelling and carving, wet and dry clay

The skillful use of clay relates a great deal to becoming aware of, and using the various stages of wetness and dryness of the clay.

The softest clay allows the most spontaneous, fast and imaginative sculpting, as it is responsive to the most subtle, and even accidental of movements. This sensual and tactile response to the smooth clay triggers images, thoughts and emotions, thus creating forms that often appear “new”, and original .

However, at this early stage, the form can easily lose shape and the form needs to be supported by hard implements ( for instance lids of various sizes) . Hand movements have to use very little pressure and be careful; this stage encourages stroking motions with the side of the index finger. Pinching out shapes should be avoided, as the clay becomes too thin, frayed and brittle.

Harder clay can both be gently slapped with a wooden bat into shape, and carved, cut and filed; wire tools peel away layers of clay, like with a potato peeler.

These two stages of sculpting and clay might correspond to complementary stages in one’ s relationship to the sculpture:

1. finding the idea, discovering the form by choosing between many options early on;
2. reflecting on and assessing what has been found: Simplifying, clarifying the form, and thereby letting the sculpture have more visual impact.

When building a taller sculpture, it is preferable to use drier and stronger clay at the base, as pressure and weight of the sculpture is bearing down . A blow heater can be positioned 20 cm opposite the sculpture, at various heights, starting at the base of the sculpture. As the sculpture grows, the heater can be raised on supports that control the right height. The heat is evenly distributed because of the constant movement of the turntable. As the sculpture rises, so does the heater…

Another method is to start a sculpture from wet clay at the end of the session, and when most things are in place, leave it to ( naturally) dry for one to three days between sessions, fully supported and held in position.

When the sculpture is dry enough to keep its shape, all the supports can be removed. The sculpture can be positioned sideways either on one’s lap, or on a cushion, to reach different parts of it, and to have a fresh and unprejudiced look at it from unfamiliar views.

The hand or lap-held position can also create a closer relationship to the work – it becomes part of oneself, or one’s body, rather than remaining a separate object. This emotional response engenders a different vision, and theus creation. Henry Moore used this method a great deal to start off and generate ideas for sculptures , creating small “Maquettes” (= three dimensional sketches)

Hollowing solid sculptures from the base with a wire tool is a great opportunity to make sure that the clay is never thicker than 3 cm (the base is least visible point in the sculpture).

If this is not possible or sufficient, you need to cut a rectangle into the sculpture at a place with the least detail (not the face for instance – but the back head instead). Keep that harder clay rectangle, while using the wire tool to empty out the sculpture from inside, using the handle for the furthest possible (angled) reach.

Straightening the base can be a good opportunity to re-balance a sculpture by working on the underside, on its base. The whole view , and balance of a sculpture is affected by a slight change of the angle of the base.

Very often, early sagging of the (heavy/tall) sculpture has to be undone, by correcting the base, and thereby straightening the sculpture. As the newly added clay might still be soft, it is important to add external supports to the work, and heat to give it a chance to harden and strengthen quickly.

Surface and texture

Rough texture can be created from very wet clay that is scrunched up between fingers; many tools can be experimented with for texture – forks, garlic press, wire or wooden tools.

Very smooth surface is made by “burnishing” leather hard clay with a metal spoon, burnishing tools of varying size, or a pebble. This often helps create a clear and simple outline.

Choosing the clay

I usually keep two different kinds of clay, all stoneware and grogged:

Pink Crank craft: Suitable for most sculptures:, the “crank” is clay dust fired, and mixed back into the clay body. It is strong yet flexible, but does not allow the most precise detail ( fires at 1170 -13.00C)

Grey stone ware: Firing off-white, but similar to above (1000 – 1300C)

Coils, slabs, solid clay

Clay can be used solid, which allows the greatest spontaneity, as nothing has to be planned; though in larger sculptures, the problem of sagging is magnified. When the surface is harder, it can be (—>) hollowed out. It is important to remember this, as sculptures exceeding a thickness of 4 cm explode in the kiln. Hollow sculpture can be either coiled or built up with leather-hard and already-dried slabs.

Coils are “snakes “ of clay, squeezed between fingers and thumb, and built on top of each other. The bonding (smearing, stroking) between them is important, both inside and on the exterior of the sculpture. Sometimes a coiled sculpture is built around cardboard, or is filled with newspaper or bubble wrap to strengthen its shape.

Slabs are created from clay that is flattened to 3 cm thickness: make a square with the four sides held by batons on top of a plastic or paper sheet; fill up with clay you press down; use a rolling pin over it, creating an evenly thick slab. Joining slab to slab, the repair techniques should be used.

Ideas and planning

Solid small sculptures can be a more spontaneous affair – a vague idea, for instance a figure, or even no mental picture at all might be enough to get started. The image is generated between the sensuous experience of the material, that stimulates the imagination, and the eyes watching what is happening. This is why the emerging sculpture needs to be at eye level to create the feedback from the creator and maker.

However, with larger, coiled or slabbed sculpture planning can become more important. A small maquette ( clay sketch) can help work out ideas, and test it from all views. Or drawings can help to establish and play though possible options. A drawing could be enlarged, transferred onto cardboard, and be covered with a slab, to be built into a third dimension. A lot of the creativity and inventions originate from this transferral of the drawing into three dimensions – problems, or options appear that one has not foreseen.

Armature

Wet clay sags and loses its intended form or collapses. Therefore, all clay sculpture is a dilemma between needing sufficient strength to hold it up, and wanting the flexibility for the work to evolve naturally, and to be able to easily change one’s mind.

Most sculptures become their own armature through drying, sometimes speeded up through using the blow heater; or sometimes left to dry naturally : Initially, they might need to be supported externally and often only provisionally.

Some sculptures need internal supports

Wire exists that can be fired. It has the advantage of being able to curve to follow the form. Barbeque sticks are another option, as they can be left in the sculpture and fired. Alternatively a pipe or dowel held in a cement block , or welded to a steel base makes for a flexible armature. the stick or pipe needs to be covered in plastic, so the clay does not attach to it, and the sculpture can be slid off it at the end of the process.

Careful: the clay will shrink, the armature will not, which often means that the sticks will show at a drier stage of the sculpture , and need to be covered again with fresh clay. There are also L-shaped external armatures , either fixed or flexible.

Keeping sculpture damp, letting it dry

If your sculpture is finished, leave it uncovered – but make sure it is taken off its pipe armature, so it does not attach itself to it! As it dries, you/or I might have to repair parts that crack.

If you want the sculpture to become self-supporting through greater dryness and hardness, leave it uncovered for 1 – 3 days of natural drying

If you want to keep the sculpture till the next session exactly at the same stage of dampness, cover thoroughly with 2/3 plastic bags, also from underneath, where air can penetrate and dry the sculpture .

Repairs on a wet sculpture that is sculpture is sagging or collapsing:

Introduce an armature retrospectively and use external supports, use heat from the blow heater applied evenly to all sides of the sculpture positioned on its turntable take it as a signal that you should stop building any further, and instead consolidate and strengthen what you have got Dry sculpture repair.

Clay has different shrinking rates, depending on its dampness or dryness. This fact adds to the challenge of repairs to a dry sculpture. Crisscross with a thin bladed tool or knife the location of the repair, and dampen it with water sprayed or brushed on , taking care that the sculpture’s base is not flooded with water. Repeat this process in different places till the knife can cut to a depth of 3mm. This will provide a surface deep enough to enable a strong bond. Use as dry as possible clay for the repair, to reduce renewed cracks due to shrinkage of wet clay. When the clay is very hard, score and brush it with slip first, before adding harder clay..

If the clay is very dry, use either vinegar, or preferably a brewing product in mixing the slip (or buy a repair kit from a ceramic shop) .Check after one or two days, if a crack has re-emerged – repair again if necessary.