WHAT IS THE CASTING LAB FOR:
Before you can use the Casting Lab you need to know what you can use the lab for. The Casting Lab is where you can cast plaster and concrete, use Mod-Roc and model using clay. These are the main materials that the ceramics lab is used for and these can be purchased from the Lab Shop. Silicone and resin cannot be used in the ceramics lab. Silicones and resins must be used in the Spray Room. Other materials such as papier mache are suitable but please check before using. If you are casting into a mould, this will need to be made prior to using the Lab, in one of the other labs (Woodshop, CNC, Project Space).
MATERIALS:
In the Casting Lab you can use many materials. The three main materials and the three covered in the Essentials are Plaster, Clay and Concrete.
Plaster:
Plaster is bought as a fine white powder (Calcium Sulphate Hemihydrate) when mixed with water becomes a liquid similar in consistancy as double cream. The water starts a chemical reaction that converts it from a liquid to a solid, all under an hour (it might take several days to fully cure and dry out). This mean plaster is a great material for casting with.
Clay:
Clay is is a fine grained natural soil material dug from the ground. When wet it is putty like with great plasticity. Becuase of this plasticity it is used in many ways; potters 'throw' it on a wheel, it can be rolled and cut, coiled and carved, it can be pressed into moulds or thinned with water to a liquid and poured into plaster moulds. To convert it from a soluble clay to a ceramic, once 'bone dry', it is fired in a kiln above 600 C. After this it can be glazed with a huge variety of colours. The glaze is a coating of a liquid suspension of glass minerals which are then refired at 1200 C, creating a glass like coating on the outside of the ceramic body. Bricks are unglazed fired clay, your tea cup is fired clay which has been glazed.
Concrete:
Concrete is the second most used material on earth after water. It is a combination of cement (the binder) sand (filler) and course aggrigates (for strength). Like plaster, when water is added it begins a chemical reaction that converst it to a solid. Unlike plaster it is a slow process taking upto 24 hous to solidify and 28 days to get to stength. It can continue to cure for years after.
HAZARDS AND CONTROLS
The Hazards involved in the lab are from the materials used rather than the machinery. Read carefully as you will be tested.
Plaster:
- HAZARD: When curing, plaster creates an exothermic reaction. If you cast plaster around your hands in a bucket, the plaster will start to harden and heat up, your hands will start to cook, and will not be able to remove them. You will loose your fingers. CONTROL: DO NOT CAST YOUR BODY PARTS.
- HAZARD: For people with very sensitive skin, plaster can dry your skin. CONTROL: Wear gloves if you have sensitive skin.
- HAZARD: Working with plaster can ber very messy. CONTROL: Small volumes of plaster will always be safer and cleaner. Larger quantities (more the 3kg) should only be used with staff assistance.
Clay:
- HAZARD: When dry the dust is hazardous to your lungs. CONTROL: Only use clay when wet. DO NOT SAND DRY CLAY.
- HAZARD: Toxic fumes emmitted from the kiln. Once the clay has dried it gets fired in a kiln. COTROL: Only clay can be fired If you want to fire your clay you cannot add anything into the clay as this will burn in an unpredictable way.
Concrete:
- HAZARD: Cement is very corrosive to your skin and eyes. CONTROL: You must wear heavy duty gloves that we provide, wear glasses at all times and avoid making the dry material airborne.
- HAZARD: Once cured concrete is very heavy. if dropped it could break your foot. CONTROL: Do not cast large quantities (over 4kg) with out assistance.