Coatings for ceramic fibre have been promoted at various times with promises of improved efficiency and safety. These coatings are intended to be sprayed onto the surface of the fibre, and are supposedly suitable to be sprayed onto kiln elements. The composition of the coatings appear to mostly alumina and silica, with some calcium oxide and zirconia, which when fired, create a crust or shell over the fibre. Potential users of coatings should be aware of some possible problems:-
The manufacturers of Kanthal element wire, used in almost all electric kilns, do NOT recommend the use of any coatings on their wire. Spraying any coating on elements may lead to premature failure of the elements, and would immediately negate any warranties.
2. Many modern ceramic fibres already contain Zirconia, and these fibres form a protective crust when fired. The use of any additional coatings overloads the surface and causes cracking of the crust, which then breaks loose and drops onto the pots below. The hot-face fibre will then have to be replaced. Thermal Ceramics recommended that no coating be applied to their Zirconia fibre, such as Cerachem 1400. Many manufacturers and suppliers use these types of fibre. Once again, any warranty will probably be voided by the use of any coatings on this fibre.
The above comments do not apply to non-Zirconia enhanced fibres, but I recommend that the manufacturer or repairer of a kiln be consulted, and consideration be given to the possibility of warranties being voided, before any coating is applied to ceramic fibre.