Non-stick

The non-stick interior of modern kitchenware is the most slippery material known to technology. It has approximately the same friction rating as ice, so if streets were coated with it they would be almost impossible to walk or drive on.

The non-stick finish, called PTFE, allows scrambled eggs or toffee to be cooked without leaving a sticky mess clinging to the pan. The same slippery quality also makes PTFE ideal for coating artificial hip joints, which must move with the least amount of friction.

PTFE is one of the most remarkable of man-made materials, and slipperiness is not its only unusual quality. It resists both very high and very low temperatures; it is quite impervious to attack from almost all chemicals; and it does not conduct electricity.

PTFE stands for polytetrafluoroethylene. It was discovered almost by accident in 1938 by an American engineer, Dr Roy Plunkett, when he was conducting experiments for the Du Pont company on a chemical used for refrigeration. The Du Pont trademark for the discovery was Teflon.

PTFE is a difficult substance to deal with, and no widespread consumer use was found for it until a French engineer, Mark Gregoire, became one of the first people to appreciate its domestic applications. He marketed the first non-stick pans under the name Tefal in the mid-1950s. Other manufacturers then produced a wide range of cookware, bakeware and appliances coated with PTFE.

However, from the early 1940s a wide variety of industrial uses had been developed. PTFE’s slipperiness was put to use in bearings – machine components that support rotating shafts. PTFE bearings are known as self-lubricating because they need no lubrication other than their inherent slipperiness. To increase their strength, they are usually reinforced with other materials, such as glass fibre and graphite. They are used particularly in chemically testing environments in which metal bearings would corrode, such as for pumps in acid treatment plants.

 

Spray-on surface

To make a non-stick frying pan, PTFE powder is mixed with water, sprayed on the pan and baked.

Heart valve The ring of a heart valve left) is covered with PTFE- coated fabric vhich is stitched to he heart. The PTFE s chemically inert, o it does not ause infection.

Sun and space The plastic dome of this sports stadium in Japan is coated with PTFE to reduce the heat of the sun’s rays and keep the stadium cool. Astronauts’ pressure suits have several layers of material, including one of Teflon-coated, fireproof, abrasion-resistant cloth.