Garments designed to keep their wearer's skin at a largely constant temperature have been developed by researchers at the two US companies Frisby and Outlast Technologies. To do this, they incorporated millions of tiny microcapsules filled with a waxy substance into the fabric. It can absorb and release heat without changing its temperature, going from solid to liquid, and vice versa. When the body produces excess heat through exertion, the material liquefies in the microcapsules, absorbing the body heat. This causes a cooling effect: sweating is prevented. When the body produces little heat of its own, liquid wax solidifies as soon as the temperature between the skin and the fabric drops below a certain level. It releases the previously stored heat again. The result: The body surface does not cool down. By varying the chemical structure of the wax, it is possible to determine exactly at what temperature the body surface should be kept. The capsules are to be woven into winter gloves, for example, which ensure that skiers do not freeze while standing at the lift or sweat on the slopes.