Aramid or Chemically Treated (FR fire resistant) Fabric?
A certified racing suit’s fabric will either have been woven using an aramid fiber or made with a chemically treated organic fabric (FR.)
ARAMIDS are synthetic, technical fibers that have inherent properties including heat & flame resistance, low thermal conductivity, lightweight, resistant to abrasion, own a high tensile strength, have resistance to organic solvents and chemicals oils.
The fire resistant properties of an aramid fiber remain with the fabric and cannot be washed out.
Avoiding the complicated science of fire-retardant fiber compositions, it is simpler to state that there are multiple fire-retardant aramid fibers used in safety clothing. For motorsports Nomex® from DuPont™ is the preferred (meta-aramid) material.
Most aramid racing suits will be made with 100% Nomex®, or blended with another aramid fiber; or an organic material; or a fiber that has other benefits for driver comfort and performance - such as elasticity, breathability, anti-static behavior...
The blend and the degree of Nomex® used in the fabric will decrease or increase the price of the suit. Nomex® is proprietary and expensive.
The blends and composition of an aramid fabric can significantly increase the suits characteristics including thermal resistance, weight, appearance and flexibility.
Stretch panels are manufactured using highly, technical aramid fibers that have been developed for elasticity and breathability. Their inclusion in a suit benefits the driver but can significantly increase the price of the suit.
THE CHEMICALLY TREATED (FR) FABRIC (usually cotton,) gains its flame resistance from being treated with a flame resistant chemical. The process produces a lower cost fabric. The downside the treatment is not permanent and, to meet the SFI & FIA standards, will be heavier. Frequent washing, regular use, exposure to certain elements causes the suit to lose some degree, or all, of its flame resistance. This can start at the eighth wash.
Proban FR cotton, Pyrovatex FR cotton, Indura FR cotton are all registered brands frequently used in the manufacture of ‘wallet friendly’ racing suits.
FR cotton suits are always heavier. Cotton is inherently heavier than synthetic thread. In addition, to pass the thermal tests (TPP,) multiple layers will have been used.
Remember no matter the fabric all the suits have to pass the same SFI and/or FIA standard tests. It’s how they achieve this which leads to the significant differences and costs of the suit.