the hot parts of the burner. Evaporating fuel from the wick removes heat from the top parts of the burner and subsequently the fuel at the bottom receives less heat. This slows down evaporation through the center while increasing the gas pressure inside the wall, spreading the ring of flame outwards, inwards, or vertically depending on the jet directions, while the center of the burner produces almost no flame, leading to a more controlled burn and faster starting. Suitable wick materials include fiberglass or cotton cloth. The wick will not burn because the evaporating fuel keeps it cool; also the pressure inside prevents oxygen from entering the hollow until the burner can no longer produce enough gas to support a flame. Cellulose cigarette filters wick fuel efficiently upwards but melt and burn in all but the least powerful designs. Other wick materials in use are Kevlar and other aramid fibers, carbon felt, fiberglass, and even toilet paper. Aluminium-can construction The stove is made from two aluminium can bottoms. An inner wall is cut and rolled from the can material. A ring of holes is pierced into the top with a pin. Parts can be glued with silicone sealant, high-temperature epoxy, or sealed with aluminum (thermal) foil tape, although this is not necessary. Total height is less than two inches (50 mm), though dimensions may be increased to hold more fuel or decreased to take up even less space. The choice of aluminium has several advantages—light weight, low cost, and good thermal conductivity to aid vaporization of fuel. Modifications to the surface such as inking or painting a dark color increase the amount of radiant thermal energy captured by the stove body and change the stove's burn profile as a function of time, fuel load, and ambient temperature. Many designs require priming to get started and most are regenerative and stable during operation. Alternative construction materials have been used, including stoves made of tin cans such as cat food tins, tuna cans, and juice cans — the basic design is very similar. Windscreens/stands can be fabricated from tin cans, cut to size with ventilation holes added. Steel beverage cans of the classic 12 ounces design are still in limited use and while they are heat resistant, their coating will burn off and they will rust if not cared for. Operation and performance Each stove works well to supply one or two