Originally published in Ceramics Technical.

MOULDS CAN ENHANCE A MORE FREE-FLOWING creative expression of handbuilding clay. Also they can help the artist deal better with some of the problems of clay. One can save wasted hours. Using a mould can speed up the entire building process. A mould has other uses besides reproducing the same clay form over and over again. The clay heads featured in this article were hand pressed out of the same mould. When the clay heads are removed from this two piece mould they are just less than leather hard resulting in lightweight hollow forms that I can move easily. I can still change the clay in any way that I like. I can express many different versions from the same form what would seem to be impossible in one sculpture.

The question of ‘who and what we are and what is our purpose’ is a recurring theme in my work. The oversizing of the heads compared to the normal size of a human head is a technique that has been used down through the different periods of art history to convey the importance of that person or theme. In my work I have focused on human and animal heads and use live models to examine and replicate their form in a much larger size what they actually are. Using photographs of the subject is also helpful. I build, carve and model images into solid clay forms, pounding the clay with my fist. The solid clay form gives some resistance when I want to push in or dig or scrape out some areas. The moulds address the logistical requirement that clay sculpture needs to be hollow to fire properly and a mould allows you to build without internal walls. An added plus of a hollow sculpture is weight reduction. Before incorporating moulds into my building process, breakage was a serious issue, which caused countless hours of lost time.

STAGE 1 – Building the solid clay forms. The original solid sculpture can involve much clay and many hours. Build on the ground or on a durable table because of the amount of clay and the weight of the mould built around it. Recycled clay is suitable for this purpose. In the end the original can be destroyed and the clay can be reused for another sculpture. There is an important issue regarding mould-making that you must give consideration to before making your pieces, that is, dealing with the undercuts in the original sculpture. You must think of the direction that you will attempt to pull your mould off the sculpture and what could hinder the plaster mould being removed easily. A mould piece should freely detach itself so plan ahead. A Murphy’s oil soap and water mixture must be applied, to the surfaces that will be touching the next mould piece to prevent the plaster forms sticking together. I recommend that you don’t make individual mould pieces heavier than what you can handle easily.

STAGE 2 – Making the two-piece press-mould. Start by making the centre line of the solid sculpture original from the bottom of the neck area where it touches the table, up to each ear, and push the wooden or other shims down into the soft clay. Going from ear to ear by moving over the top of the head, do the same again with more shims. You have now divided the form into two sections; face front and back of head. The shims will keep the two sides of the mould separate. I also apply small pieces of grey electric tape to cover the small holes between the shims. Apply a mixture of oil soap with water to both sides of the shims and tape. Now you are ready to mix up a bucket of plaster. Half fill the bucket with water, and sift or pour in a 25-pound bag of plaster. I use an electric drill and paint mixer blade to mix the plaster. I make the two mould pieces by applying the plaster while the sculpture is standing on its neck. I wait until the plaster is as thick as whipped cream and then work quickly before it hardens too much (a second person assisting you with this part is helpful). I wipe the outside of the mould with a damp sponge so it will be smooth when it hardens.

STAGE 3 – Preparing to make the second piece of the mould once you have completed one side of the mould. Carefully remove the shims. Before you do anything else make sure to carve out at least two large indented negative space triangles on either side of the mould to make some keys. When you make the second side of the mould it will automatically fill in the negative key spaces on the first mould. The new positive key pieces which will fit in the key pieces when you reassemble the mould later. Once your plaster is mixed up and almost ready to harden, quickly make the second mould piece by applying the plaster to the other side. If you missed getting some spots to the desired 2.5 - 4 cm (1 1 1/2 in) thickness then you can mix up smaller batches of plaster to fill in and reinforce thin spots on the mould pieces. I let both pieces harden for several hours, then I turn the whole mould on to its side with someone helping me. When I can access the flat bottom of the neck of the sculpture such as this way I can scoop out all the solid clay out with a pot-tery-carving tool or my hands. The plaster press mould will last as long and strong as how well you make it (areas of the mould too thin with crumble when you press clay against them but can be reinforced with more plaster. All of my head moulds have lasted more than three years, despite numerous usages and some chipping on the edges.

STAGE 4 – Customising the raw form. I hand-press the clay into the moulds with them lying on their sides looking up at me as if they were two baby cradles. I make sure to build up the edges 5 cm (2 in) thick where the front mould piece and back will touch each other when the two sides of the mould are put together. I let the clay stiffen in the moulds overnight before I try to join the two sides together. Join the two sides of the mould together to form a complete clay head. After you have pressed the clay into the mould, it will be too soft and the clay will fall out so it is advisable to let the clay stiffen in the moulds to almost leatherhard. I want the inside parts to stiffen up but I want the places where the clay touches to stay moist. To achieve this I cover those areas with aluminum foil to keep them from becoming too dry. Make sure to remove the aluminum foil before you join the front and back pieces together. Poke holes all around the inside of the sculpture with a fork before you join the two sides together. How long you leave the clay in the mould depends on how wet or dry the plaster remains. After I make my moulds, I put them in the sun outdoors for several days or in the winter next to warm radiators. Once the form comes out of the mould the head sculpture should be about leatherhard and able to stand up on its own neck. I work freely on the leatherhard clay, making marks, adding parts, etc. If it breaks at this stage I can go back and press out another head form. The impression of the original sculpture that I laboured so hard over is still there preserved, captured into the mother mould and not lost. After the last glaze and gold firing I spend time painting on the finishing touches with oil or enamel paints. I prefer to have my pieces retain an unfinished quality to them. If you paint them with too much detail they will lose some of their visual freshness.

Gilda Oliver is a ceramic artist and a teacher at Baltimore Clayworks, Maryland. Photography by Katie Walsh. Text & images ©.

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