Cold wax strips may need be applied repeatedly at the same area to remove all hair. Meanwhile, hot wax uses melted wax, and may or may not require strips. The wax is applied while still warm and spread evenly and thinly. As the wax cools, it moulds onto the skin and grips at each individual hair strand. The wax is supposed to warm up from the heat of your body as you spread the wax. Firstly, the 'cold' wax needs to be heated. ... Skin should be dry in order for the wax to stick properly which is why powder is often applied pre-waxing. Just washed skin takes a while to fully dry and is not ideal for waxing.