Materials, Tools and Workshop Safety
This domain tests whether you can identify modelling and sculpture materials, choose the right tool for each, and work safely in a school workshop. CHSE +2 Vocational questions often turn on material behaviour and safety rules rather than on lengthy theory.
Materials and tools
- Natural clay is plastic when damp, leather-hard when partly dry, and brittle when bone-dry; it shrinks on firing.
- Plaster of Paris sets by a chemical reaction, not by drying; it is used for moulds, waste moulds and casts.
- Wax (paraffin, beeswax) is thermoplastic: it softens with heat and is used for lost-wax patterns.
- Papier-mâché is paper plus adhesive, built in layers over a form; it dries by evaporation.
- Match tools to material: wooden and wire-loop modelling tools for clay; spatula and rasp for plaster; chisels and mallet for wood; riffler/rasp for stone; moulds and release agents for casting.
Safety rules
- Control silica and plaster dust: wear a dust mask, wet-clean surfaces, never dry-sweep.
- Plaster gives out heat as it sets; do not cast a thick mass in your hand or a closed container.
- Melt wax in a double boiler, never over an open flame.
- Cut away from the body, keep chisels sharp, and clamp work securely.
- Keep solvents and spray fixatives away from flames and use ventilation.
Worked example
A student mixes plaster in a plastic bucket, and the mixture becomes hot and stiffens quickly. Reasoning: plaster sets by an exothermic hydration reaction. The safe response is to add plaster to water (not water to plaster), stir gently to avoid air bubbles, use a clean bucket, and let the unused plaster set before disposing of it in a bin-never pour it down the sink.
Traps that cost marks
- Confusing plaster with cement or clay.
- Adding water to plaster and stirring violently.
- Using kitchen utensils and unlabelled containers.
- Ignoring dust, hot wax and sharp-tool hazards.