ceramic or silicone rubber, or a combination of both. The tube is drawn through a die to compress the powder and maximize heat transmission. These can be a straight rod (as in toaster ovens) or bent to a shape to span an area to be heated (such as in electric stoves, ovens, and coffee makers). Screen-printed metal–ceramic tracks deposited on ceramic insulated metal (generally steel) plates have found widespread application as elements in kettles and other domestic appliances since the mid-1990s. Radiative heating elements (heat lamps): A high-powered incandescent lamp usually run at less than maximum power to radiate mostly infrared instead of visible light. These are usually found in radiant space heaters and food warmers, taking either a long, tubular form or an R40 reflector-lamp form. The reflector lamp style is often tinted red to minimize the visible light produced; the tubular form comes in different formats: Gold coated - Made famous by the patented Phillips Helen lamp. A gold dichroic film is deposited on the inside that reduces the visible light and allows most of the short and medium wave infrared through. Mainly for heating people. A number of manufacturers now manufacture these lamps and they improve constantly. Ruby coated - Same function as the gold-coated lamps, but at a fraction of the cost. The visible glare is much higher than the gold variant. Clear - No coating and mainly used in production processes. Removable ceramic core elements use a coiled resistance heating alloy wire threaded through one or more cylindrical ceramic segments to make a required length (related to output), with or without a centre rod. Inserted into a metal sheath or tube sealed at one end, this type of element allows replacement or repair without breaking into the process involved, usually fluid heating under pressure. Combination heating element systems Heating elements for high-temperature furnaces are often made of exotic materials, including platinum, tungsten disilicide/molybdenum disilicide, molybdenum (vacuum furnaces) and silicon carbide. Silicon carbide hot surface igniters, which are heating elements designed for igniting flammable gas, are common in gas ovens and clothes dryers. Laser heaters are also being used for achieving high temperatures. See also Heated hose Heating mantle Positive temperature coefficient Thermoelectric effect References Heating