Metal Casting
As part of my master's studies I took part in a metal casting course. The course took 11 days all together and during that time each student created a bronze cast sculpture of their choice.
The first days were spend getting to know different casting methods briefly and playing around with cheese wax. The casting technique used for the class was "lost wax" technique, where the sculpture is first modelled out of cheese wax. I chose to model a sitting fox.
Once the cheese wax sculpture was ready it was attached to a pouring cup (also made out of wax) and straws were added to act as gas channels. The whole structure was build onto a board to make the next stage easier.
Once all the bits were attached together a plaster mould was created around the sculpture. First a length of chicken coup wire was bend into a circle and a rubber sheet was wrapped around it. The wire/rubber shell was placed around the sculpture. Then a slurry of brick gravel, water and plaster was poured on top of the sculpture. After the slurry hardened the plastic wrap and wooden base were removed.
Next the moulds were placed in different ovens, first to melt the wax out and then to burn out everything else (straws and toothpicks). This way a negative of the sculpture was left inside the plaster mould. Then the molten bronze mixture was poured into the plaster moulds. It only took about two hours for the mixture to cool enough for the mould to be opened.
Next all the extra little channels and bubbles were removed from the sculpture. Then I polished the sculpture a little bit before the pouring cup was removed with an angle grinder. I used different power tool drills to remove the last of the excess material from the sculpture and kept polishing the surface.
Finally I polished the surface to a proper shine with polishing compound.
Because I was fast with my first piece I had time to create another sculpture as well. I chose to make a small leaf shaped candle holder. This I created from start to finish in 5 days, starting wax sculpting on a Monday and finishing patinating and polishing on Friday. The metal pour wasn't a 100% successful but that did not matter to me.
Once the leaf was out of the mould and cleaned, I polished one side of it and used sodium sulphide to darken the other side, creating a nice contrast of shiny and matte texture and dark and light colour. I also grinded the bottom so the sculpture sat flat on a table.
The finished pieces together.
