Since 1975 the FIA has required that driver clothing be flame retardant so as to offer protection in the event of a fire. That used to mean heavy, five layer, NASA-spec race suits. Nowadays the key is Nomex®, a fire-resistant, lightweight artificial fibre which undergoes thermal testing in the laboratory. It is subjected to an open flame with a temperature of 300 to 400 degrees Celsius that acts on the material from a distance of three centimetres - only if it fails to ignite within 10 seconds can it be used in a drivers overalls.
The modern drivers race suit (also worn by pit crews) features elastic cuffs on wrists and ankles and is made of two to four layers of Nomex®. A completed multi layered overall undergoes 15 washings as well as a further 15 dry cleaning processes before it is finally tested. It is then subjected to a temperature of 600 to 800 degrees Celsius. The critical level of 41 degrees Celsius may not be exceeded inside the overall for at least 11 seconds.
The zip on the suit must also be able to withstand the same temperatures and must not melt or transfer heat close to the driver's skin. Even the thread used to sew it together must be fire resistant, as must any patches, although the majority of sponsor logos are now printed on - a change that has helped cut the weight of overalls by over half a kilo in the past few years. But not only are modern race suits light, theyre also breathable to in order to allow the several kilos of sweat produced by the driver during a race to escape.
The suit must also have two large handles on the drivers shoulders. These straps must be capable of supporting the combined weight of the driver and his seat, which in the event of an accident can be removed from the car by marshals as one, in order to minimise the risk of complicating injuries.
The drivers gloves are also made of Nomex® and are thin, with suede leather palms to provide the sensitivity of feel necessary for steering. The driver's fireproof ankle boots are made of soft, cushioned leather and, similarly, their rubber soles are far thinner than those of ordinary shoes to provide accurate and slip-free contact with the car's pedals. Underneath his race suit the driver wears a further layer of flameproof underwear, and under his helmet a fireproof balaclava.
Did you know that drivers in an overall made of Nomex® fibre can survive for 11 seconds in temperatures of 840 degrees Celsius. In comparison, the maximum temperature in a sauna is 100 degrees. In a house fire it would be up to 800 degrees, while the lava in a volcanic eruption reaches between 750 and 1000 degrees.