My second workshop consisted of making vina moulds, which is the pouring of reusable hot rubber. The material comes in blocks which are cut up and heated until a liquid.
The process of vina mould are:
- Rolling a thick slab of clay (roughly 1 inch)
- Pressing the item into the clay
- Creating clay boarder around the slab, making sure its taller than the item.
- Whilst heating the vina in the microwave for roughly 5 minutes
- Pour the vina in the clay mould making sure to cover the whole item
- Leave to set
I decided to try something a little weird and cast an Oreo.
I wanted to cast the whole biscuit instead of one side, and actually create a 3D cast of the Oreo. To do this I put a screw in the bottom of the biscuit and pushed it into the clay, this allowed it to stand up without touching the clay creating a whole cast of the Oreo.
Vina moulds do have some draw backs for example you can not use dry or sinewy objects. This is because the the mould will try and pull at the air pockets in the object rewening the mould. However vina mould can create perfect moulds with delicate and beautiful detail.
If there is any excess vina left over it is necessary to put it on the floor till it makes a thin disc. this will then allow you to easily and efficiently cut and reheat the vina next time.
The next step would be to use the mould to create a wax cast, as shown in this photo.
wax moulds are created from vina mould to end up being used in Bronze casting.
Similarly to vina mould wax chunks are out into a pot on a designated burner and allowed to heat up. once it is all melted and hot the wax is poured in to the vina mould, and allowed to cool. Once it is cool the wax cast is done.
Another technique is to weld two pieces of set wax together. By placing a metal palette knife on the burner you can put the hot tool between the wax pieces allowing them to melt slightly and join them together. this process does involves the wax spitting and can be a bit dangers. Caution is necessary.