Non-Asbestos Fibre materials are so-called because they fill the gap in the range of gasket materials previously occupied by asbestos. Asbestos, although considered to be a dangerous material, had excellent heat resistance properties, which is why it was utilised so widely in high temperature applications. When asbestos was outlawed, replacement materials were needed; so these asbestos-free, or non-asbestos, materials were developed to perform the same function, but without the corresponding problems.
These materials are now commonly comprised of aramid fibre (Kevlar), carbon and other non-organic fibres, which are in turn blended with different polymers to meet different applications: most commonly nitrile rubber, for fuel and oil resistance. These materials can also be graphite coated for non-stick and steam resistance, mixed with PTFE for excellent chemical resistance or with EPDM for potable water applications.