When casting metal by making use of shaped and formed expanded polystyrene ( 'lost polystyrene' method), it is - essential to ensure that exhaust ventilation LEV is effective, to remove gases to the outside. See also information on cutting/working with polystyrene: Working with Plastics and Polystyrene.
Polyurethane should not be used in the same way as polystyrene i.e. the 'lost-foam' process.
When metal casting into pre-made plaster moulds, it is essential to ensure the moulds have been fully dried and that no moisture is evident in the mould or casting area. The plaster mould should always be buried into the casting pit and firmly surrounded with casting sand to support the mould and prevent any leakage of hot metal.
After casting, allow the casting sand (oil bonded sand) to cool fully (1-2 hours) before removing the sand mould or releasing the cast metal following the lost polystyrene casting, to enable smoke and gases to fully clear.
Always prepare steel or ingot moulds when metal casting, to enable all the hot metal in the crucible to be used after the mould is filled.. It is essential to pre-heat steel or ingot moulds prior to pouring.
Metal casting should not be attempted unless the teacher is properly trained and qualified and the conditions are appropriate.
For all metal casting activities, suitable PPE must be worn by all participants ie, eye protection/face mask, heat-resistant gloves, leather apron, spats, gaiters and suitable footwear. Observers should stand more than 2 metres from the casting activity and should also be suitably equipped with PPE.
CLEAPSS guidance - MRAT - 020 - Casting, sand and fumes.
CLEAPSS guidance - MRAT - 019 - Casting
CLEAPSS Resource - Pewter casting
Oxy-fuel welding and flame cutting should carried out only under the direction of a fully qualified teacher who has successfully completed an approved course of training. Oxy-fuel welding and flame cutting must not be undertaken in art rooms. This should only be carried out in a specialist welding facility.
CLEAPSS guidance - MRAT - 029 - Oxy-Acetylene Welding and Brazing
CLEAPSS guidance - MRAT - 029 - Oxy-Acetylene Welding Fumes
Electric welding must not be undertaken in art rooms. This should only be carried out in a specialist welding facility.
CLEAPSS guidance - GL325 - Using a welding facility
CLEAPSS guidance - MRAT - 027 - Electric Arc Welding
CLEAPSS guidance - MRAT - 028 - Electric Arc Welding fumes
CLEAPSS guidance - GL326 - Managing welding fumes in schools and colleges
Here the main concern is the fumes that are released when rosin-based solder fluxes are heated. Consequently only rosin free solders should be used. Nevertheless it is still essential that this activity only takes place in a well-ventilated area or with forced air ventilation (LEV). Burns and scalds are also a potential hazard.
mains voltage soldering irons should be fitted with rubber insulated leads to prevent damage to the leads from hot soldering irons. The use of a safety stand to hold the soldering iron between uses, will greatly reduce the risk of damage and burns and will also extend the life of the bit.
The use of Butane fuelled soldering irons is not recommended in art and design.
CLEAPSS guidance - MRAT - 016 - Brazing and Silver Soldering
CLEAPSS guidance - MRAT - 025 - Soft Soldering Fumes and Fluxes
CLEAPSS guidance - MRAT - 026 - Soldering irons
CLEAPSS guidance - GL333 - Soldering fume extraction