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 – use a dust mask. When tidying , don’t disturbe the dry clay , don’t use a brush, use 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 the clay.
The softest clay allows the most spontaneous, imaginative sculpting, as it is responsive to the most subtle, and also accidental of movements. This sensual response to the smooth clay triggers and thereby transfers images, thoughts and emotions- that often appear “new”, and original – out into the material world. However, at this early stage, the form can easily loose shape, and does not accept harder tools. Hand movements have to use very little pressure and be careful; this stage encourages stroking motions. 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 two complementary stages in one’ s relationship to the sculpture: from finding the idea, discovering the form by choosing between many options early on – to 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 clay at the base, as most pressure and weight is bearing down, and the softer the clay, the more likely it looses its form, collapses or sags.

Often, a blow heater is positioned on supports that control the right height, and angle of heat, opposite the sculpture, starting at the base; the heat is evenly distributed because of the constant movement of the turntable. As the sculpture rises, so does the 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. it I can be positioned either on one’s lap, or on a cushion, to reach different sides of it, and to have a fresh and unprejudiced look at it from an unfamiliar view.

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 thereby creation. Henry Moore used this method a great deal to start off and generate ideas for sculptures , so-called “Maquettes” (= three dimensional sketches)

Hollowing solid sculptures

That moment is a great opportunity to make sure that the clay is never thicker than 3 cm , but hollowing out the sculpture with a wire tool, starting from the base (the 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

Again, this stage can also 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 of varying size, or a pebble. This often helps create a very clear and simple outline.

Choosing the clay

I usually keep three 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

£12.50/12,5KG  (1170 -13.00C)

Grey stone ware:  Firing off-white, but similar to above

£9.00/12, 5Kb ( 1000 – 1300C)

Cheapest clay: Less elastic , suitable to sculpting with children

£6.50

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, cutting out a “plaster”, and using a wire tool to empty out the internal space, leaving the walls standing at 2 – 4 cm thickness. It is important to remember this, as sculptures exceeding this thickness explode in the kiln!
Hollow sculpture can be either coiled or build up with leather-hard (and ready 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 outside the sculpture. Sometimes a coiled sculpture is built around a ready made plaster or cardboard form (pipes etc..) or is filled with newpaper or bubble wrap to strengthen its shape.

Slabs are created from clay that is flattened to 3 cm thickness with a rolling pin, and then dried, making a space between the board and the clay with supports.Joining slab to slab, the repair techniques have to 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 the eyes watching what is happening. This is why the emerging sculpture needs to be at eye level – rather than be treated like a bit of “dead clay” handled way below one;s eyes!

However, with larger, coiled or slabbed sculpture planning can become more important.Drawings can help to establish and play though all the options; one drawing could be enlarged, transferred onto cardboard, and be covered with a slab, to be build 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, looses 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 change one’s mind.

Most sculptures become their own armature through drying, sometimes speeded up through using the blow heater, sometimes left to dry naturally : Initially, they might need to be supported externally and often only provisionally (through clay covered with plastic, or various tools, sticks, containers holding up parts of the clay, till it is dry to keep its own position).

Most sculptures intended to become larger than 30 cm within one session should have the heater dry them straight from the beginning,:especially the base needs to be extra hard to take the weight without giving way and making the sculpture loose balance.

Some sculpture need internal supports

Wire that can be fired, in two thicknesses. It has the advantage of being able to curve. Thin and thick sticks, used for barbequee, supporting plants or carpentry pipe or dowel that is held in a hole in a cement block. Dried paper clay can be used as armature.

Careful: the clay will shrink, the armature will not, which often means that the sticks will show, and need to be covered again with fresh clay

There are also the traditional external armature , either fixed or flexible, that can be bought from Tiranti

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 around or show up the armature

If you want the sculpture to become selfsupporting 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, please cover thoroughly up with 2/3 plastic bags – cover also from underneath as this is where warm air can penetrate!

Repairs

Wet sculpture repair, when the sculpture is sagging or collapsing:

introduce an armature retrospectively use external supports, use heat from the blow heater applied evenly to all sides of the sculpture positioned on its turn table 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 knife the location of the repair, and dampen it with brushed on water. repeat this process till the knife can cut to a depth of 3mm. This will provide a surface broad enough to provide for a bond. Use as dry as possible clay for the repair, to reduce renewed cracks due to shrinkage of clay.

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