Safety at Raku kilns
This SIM draws inspectors' attention to safety aspects associated with the Raku ceramic firing process.
Raku is a ceramic firing technique which, in practice, involves heating glazed ware in a reducing atmosphere to approximately 900oC and then removing it from the kiln whilst red hot and putting it into a 'secondary' or 'post firing' reducing atmosphere (normally a bin containing leaves, sawdust or similar materials) where it is allowed to cool for a period of time. The ware is then either, removed and left to cool completely or alternatively rapidly cooled in water, halting the process.
The process is relatively quick and simple allowing the user to see the results of their work in a short period of time and it is for this reason that it is often carried out in schools and other educational establishments.
Historically concerns have been raised about the precautions required and observations about the 'ad hoc' nature of the work. Of particular interest are the types of kiln used and the methods of work adopted to control the risks associated with this firing technique.
The Sector suggests the following precautions are taken:
- Raku kilns should not be operated indoors;
- Appropriate personal protective equipment should be worn when transferring the hot ware from the kiln to the reducing atmosphere, namely eye protection, heat resistant gloves / gauntlets, apron and safety footwear;
- When opening the container either during or after 'post-firing reduction', the lid should be removed so that the far side of the container from the operator is opened first, with other persons at a safe distance, to mitigate against the hazard of a flash fire;
- On no account should highly flammable liquids be added to the reducing medium due to the increased risk of a flash fire;
- Where refractory ceramic fibre is used as the insulation material in the kiln, the precautions outlined in OC 267/3 should be taken;
- Each kiln burner should be fitted with a flame safeguard device, (eg a thermoelectric device to automatically cut off the gas supply if the flame goes out);
- Adequate supports should be provided for the kiln burners so that they are securely attached to the kiln structure to prevent them being knocked out of position inadvertently and;
- Where LPG is used as the fuel source, cylinders should be properly stored and cylinders in use should be securely located in a safe, well ventilated position in accordance with Code of Practice 24 – Use of LPG Cylinders, Part 1: 2006 – Use of LPG Cylinders at Residential and Similar Premises .
Action by inspectors
Any inspector who has any information relating to the Raku firing process and the methods of work adopted by the client is requested to contact the Metals and Minerals Sector.
Inspectors should be aware of who (in terms of diversity eg men, women, disabled etc) is the target group in the sector they are dealing with. Give consideration to, and factor into the approach, any issues that may surround this audience such as literacy issues, English as a second language and disability (access needs).
Cancellation of instructions
SIM 03/2002/54 - cancel and destroy