A candle wick is usually a braided cotton that holds the flame of an oil lamp or candle. A candle wick works by capillary action, conveying ("wicking") the fuel to the flame. When the liquid fuel, typically melted candle wax, reaches the flame it then vaporizes and combusts. The candle wick influences how the candle burns. Important characteristics of the wick include diameter, stiffness, fire-resistance, and tethering. Wick types Candle wicks are normally made out of braided cotton. Wicks are sometimes braided flat, so that as they burn they also curl back into the flame, thus making them self-consuming. Prior to the introduction of these wicks specialty scissors were used to trim the excess wick without extinguishing the flame. Large diameter wicks typically result in a larger flame, a larger pool of melted wax, and the candle burning faster. In tealights the wick is tethered to a piece of metal to stop it from floating to the top of the molten wax and burning before the wax does. Candles designed to float in water require not only a tether for the wick, but also a seal on the bottom of the candle to prevent the wick from wicking water and extinguishing the flame. In some birthday candles, the wick is a stub. This limits how long the candle can burn. The Japanese Wa-Rosoku candle uses a hollow cored wick composed of Japanese paper (Washi) and the pith of rushes. Wicks can be made of material other than string or cord, such as wood and (historically) even asbestos, although they are rare. The cotton of tampons can be used as wicks for oil lamps in wilderness survival situations. Stiffeners Fine wire (such as copper) can be included in the wick. This provides two advantages: it makes the wick more rigid, letting it stand further out of the liquid wax, and it conducts heat downward, melting the wax more readily. The latter is particularly important in candles made of harder wax. Stiffeners were once made of lead, but these have been banned in the US for several years by the Consumer Product Safety Commission, due to the concerns about lead poisoning. Other core stiffeners, such as paper and synthetic fibers, may also be used. The CPSC was petitioned to ban candle wicks containing lead cores and candles with such wicks by Public Citizen, the National Apartment Association, and National Multi Housing Council