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Alumino Silicate Wool (ASW)

  • Also known as “refractory ceramic fibre” (RCF)
  • Invented in 1942
  • Commercialised in the 1950s
  • Mainly used for products in industrial high-temperature applications
  • High chemical resistance
  • Typically used from 600 °C to 1400 °C

Alumino Silicate 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 from Alumino Silicate Wools are generally used at application temperatures > 900 °C in industrial equipment such as furnaces and kilns under critical application conditions, fire protection and in automotive exhaust systems.

Key features are:

  • low thermal conductivity
  • good chemical resistance

Application of ASW

Regulatory Classification Status

ASW also known as refractory ceramic fibres (RCF) was originally classified as a carcinogen category 2 – “Substances that should be regarded as if they are carcinogenic to humans” under the Dangerous Substances Directive since 1997.

This was translated under CLP Regulation into a carcinogen category 1B “Known or presumed human carcinogen; presumed to have carcinogenic potential for humans, classification is largely based on animal evidence”.

They have been listed under the EU index number 650-017-00-8 in Annex VI part 3 table 3.1 of CLP, which specifies the information required on the labels.


Regulation (EC) No 1907/2006 of the European Parliament and the Council of 18 December 2006 concerning the Registration, Evaluation, Authorization and Restriction of Chemicals (REACH) requires manufacturers, importers and or the exclusive representative of non-European manufacturers to share data on potential health and environmental hazard and provide data to the European Chemicals Agency (ECHA) in a formalized registration process.

ASW / RCF is REACH registered and can therefore be used on in the European market.

Aluminosilicate refractory ceramic fibres and zirconia aluminosilicate refractory ceramic fibres were added to the Candidate List (containing substances of very high concern – SVHC – potentially qualifying for authorisation) by ECHA in 2010 and updated in 2011.

As a consequence, EU (European Union) or EEA (European Economical Area) suppliers of articles which contain aluminosilicate refractory ceramic fibres and zirconia aluminosilicate refractory ceramic fibres in a concentration above 0.1% (w/w) have to provide sufficient information, available to them, to their customers or upon requests to a consumer within 45 days of the receipt of the request. This information must ensure safe use of the article and as minimum contains the name of the substance.

Cartoon; Best working practices

ASW / RCF is subject to a 0.3f/ml Binding Occupational Exposure Limit Value (BOELV) under the Carcinogens, Mutagens and reproductive toxins Directive. This applies across Europe and controls should be implemented to comply. Further information on good working practices can be found in the support section.

Further specific information can be found on your supplier’s SDS.

All relevant local, state, regional and national regulations should be observed at all times when using these products.

Inclusion of RCF on REACH Annex XIV? Socio-economic implications

The “non-use” of RCF could lead to a wide range of undesired socio-economic implications; negative impacts are expected in terms of environmental sustainability, competitiveness, employment, process safety and legal compliance with plant emission regulations.

Joint industry position paper on Risk Management Options (RMO) for ASW

ECFIA, along with 14 major industry associations, has developed a joint position paper on the advantages of the introduction of a BOELV under the existing framework of the CMD. The BOELV is a much more efficient and effective way to achieve the overall objective of improved risk management, via harmonized workplace controls.

HTIW Handling Advice

Download HTIW Handling Advice in PDF-Form.