Alumino-silicate glass wools, also known as “refractory ceramic fibre” (RCF), are amorphous fibres produced by melting a combination of Al2O3 and SiO2 (see also EN 1094-1; VDI 3469 Parts 1 and 5).
Products made of alumino-silicate glass wools are generally used at application temperatures > 900 °C in industrial equipment like furnaces and kilns under critical application conditions, in fire protection and in automotive exhaust systems.

Substances considered to be of very high concern (SVHC) may be subjected to authorization. Some of the ASW/RCF wools have been identified as SVHC since 13 January 2010. See ECFIA position on the issue.