Slip Casting

Making the Mould

Stage 1

1. First I placed the baby doll head on top of a lump of clay and a wooden board (for stability). I used more clay to level the head across the centre line to create the best outcome.
2. I pushed clay into the ears, stretching the clay down to the base, to prevent plaster going into the ears and getting stuck.
   
   
   
3. I then placed wooden boards around the clay (lining up the bottom of the head to the edge of one block to create a hole to easily pour in the slip later on) and clamped them in place.
4. After mixing 600 ml of water with powdered plaster (roughly 5 scoops), I poured the mixture over the head and clay up to the centre line. This first cast would be a 'sacrificial' cast as it wouldn't be able to hold the whole shape of the cast, but would me create the top half of the mould.
   
   

Stage 2

1. Once the plaster was fully dry I removed the clamps and boards and carved off the meniscus using a potters knife to create as smooth clean edge.
2. I then coated the surface of the plaster with mould makers soap 3 times, waiting 5 minutes in-between each coat. This prevents the wet plaster from sticking and fusing to the dry plaster.
3. Using paper towel I then wiped off any excess soap, and buffed it into the surface with a cloth.
   
   
   
4. Using UHU glue, I then glued 2 natches onto the surface, leaving room around the ears for a later step.
5. I then replaced the boards and clamps, and poured another mixture of plaster over the top (600ml water and plaster).

Stage 3

1. Once dry I removed the boards and the bottom layer of plaster and clay. This half could then be thrown away as it had served its purpose.
2. Without moving the head from the plaster mould, I used a blade to flatten the surface, making it as smooth as possible.
3. I then covered this surface with mould makes soap (3 times, the wiping excess and buffing), and placed 2 more natches inside the other 2.
4. I then placed clay into the ears, making sure to end the clay at the very tip of the ears so the plaster could take the shape of the back of the ears, but would not get stuck inside and prevent me from removing the cast.
   
   
   
5. I replaced the boards and clamps, and pure another equal mixture of water (600 ml) and plaster over the top.
   
   
   

Stage 4

1. I removed the boards and clamps and carefully separated the two halves. 
2. At this point I removed and cleaned the doll head to remove and clay or paster that was stuck.
3. I then carved two tapered tunnels towards the ears onto each half of the mould, matching them up as best as I could, making sure not to mark the plaster where it had already taken the shape of the head.
4. I then applied mould makers soap to the 'ear canals' and to the surrounding surfaces.
5. I then put the two halves together, securing with tape, before pouring a smaller amount of plaster (from 100 ml water) into each ear canal. 
6. Once one side was dry, about 15 minutes as it was a smaller volume of plaster, I flipped the cast to other side and filled the other ear canal.
   
   
   

Stage 5

1. Once the plaster in the ear canals were completely dry (I waited overnight), I flattened the edges to create a flat side to the mould so they could be handled more easily and less likely to break.
2. I separated each section of the mould (in total four pieces) and let them dry separately, on top of a kiln to make sure there was no moisture left. This would be important when I used them to lessen the drying time, and create less imperfections in the finished cast. 

Casting

1. After each piece of the mould was fully dry, I put the pieces together and secured it with tape to ensure it stayed together while casting.
2. I first mixed the white earthenware slip clay (clay in liquid form) with a spatula to make sure the additives where evenly distributed and would produce a more even and stable final product. I then ran the mixture through a sieve into a pouring jug to remove any bigger or hard pieces that were introduced while mixing, and for an easier pour into the mould.
3. Once in the jug, I gave it another mix and quickly (to reduce the risk of parts drying unevenly) into the mould until completely full. 
4. Once filled I left the slip in the cast for five minutes to make surety walls were thick enough to support themselves. During this time the slip would move into the crevices and small indents, so the level would decrease and would need topping up a couple of times.
5. Once the slip was in for five minutes, I turned it upside down and shook out the excess slip, removing as much as possible before placing it (still upside down) on raises so any excess could get out.
6. After about ten minutes I removed any excess clay from around the entrance point, stopping at the neck. This would ensure that when the clay dried, it was able to pull away from the edges evenly and not get caught at the edges. If not, it could create weak points around the base of the head, and make it harder to remove from the mould. 
7. For this first cast, I left it to dry for about 24 hours before removing from the mould. After a few uses, the capillaries in the plaster open up and allow water to be absorbed from the slip clay much quicker, allowing the cast to be removed from the mould quicker.
8. After removing the cast, it is still very fragile and easily marked or collapsed, but is also the perfect time to remove the excess clay from the seams. I used a potters knife to remove the seam, and clean up the ears and any other imperfections, like around the eyes and nose.
9. Once cleaned up, I left the casts to dry fully before bisque firing them. A this point they are ceramic heads, instead of clay heads.
              
   
                      
   
   

Glazing

1. Once bisque fired, they turn completely white and are ready for glaze to be applied.
2. To prepare the glaze, you mix it thoroughly as it separates naturally. A thick sludge settles to the bottom with a cloudy liquid on top. It needs to be homogeneous in order to work and act correctly.
3. Once mixed, Dip the heads into the glaze, trying to prevent the glaze from going inside the head too much. Once an even layer is applied, set to the side to dry.
4. Once dry, remove any glaze from the base of the head (as it can stick to the base of the kiln when fired, causing damage to both the piece and the kiln when removed) using a damp carpet square or sponge.
5. Once dry it can be glaze fired, which melts the glaze to form a glossy and protective layer on the pottery.