carving, cutting and abrading stone
The varieties of stone available for carving in schools are limited and this is why Plaster of Paris tends to be cast and then cut and abraded as the easiest solution. See the page on Plaster of Paris.
UK art and craft suppliers do sell small lumps of Soap stone and Alabster for carving. These are relatively soft stones that can be easily worked with wood saws, chisels and rifflers. However, such activity will rapidly blunt these tools, which can result in over exertion or more forceful actions which can itself present a hazard. Other soft stone such as sandstone is available and might be brought in by an older pupil for their own work. Portland stone and marble are typically medium hard stones and will need proper stone carving tools to work. Teachers should satisfy themselves as to the safety of the stone material, including possible hazards from chips and dust e.g. some sandstones and slate have very high levels of silica, and some marble naturally contains small amounts of asbestos, all of which can be hazardous if not used with care, proper carving and abrading tools and suitable PPE and hygiene practices.
When risk assessing activities using stone and blocks involving carving, cutting and abrading, teachers must be aware of the process that will result in pieces being chipped off across the carving area. With harder stones, these chips can be sharp and travel some distance, posing a hazard to the eyes and skin of other pupils in the wider vicinity and also from airborne dust. Precautions must be taken to prevent such hazards affecting the pupil carving and others.
As in all carving, cutting and abrading activity, suitable PPE must be worn and the stone or material being worked should be firmly or safely clamped, or bedded firmly in a sand filled bag on a suitably robust carving bench. PPE should include suitable goggles, gloves and protective clothing, with a possible requirement for a mask and filter. Please reference HSE guidance on respiratory protective equipment (RPE). Access this here.
The HSE produces guidance on Controlling exposure to stonemasonry dust.
The HSE guidance for Stoneworkers, gives guidance on silica dust and silica levels of different types of stone. You can access this guidance here.
Building and Insulation blocks
The health hazards of the compounds used in the manufacture of building and insulation blocks should be investigated before being carved or abraded. Some may have a high silica and irritant content. Aerated blocks are manufactured with names such as 'Thermalite', 'Aircrete' and 'Breeze' blocks. Larger blocks can be created be sticking or bonding several blocks together, but risk assessments must take account of the weight and safety of lifting and working on larger blocks.
If safe to use, suitable PPE must still be worn and care taken particularly with the control of dust if cared, cut or abraded inside a studio or workshop.
All heavy materials, which could cause severe damage to feet and hands if insecure, must be held firmly in a suitable vice or other mechanical device.
CLEAPSS guidance - MRAT - 150 - 3-Dimensional Carving, Cutting & Abrading
CLEAPSS guidance - MRAT - 171 - projects, Testing, Experimental & Novel Activities Materials