1354022 Resistance heating elements KALLE AG and KLIMATECHNIK-ANSTALT 20 May 1971 [22 May 1970] 16012/71 Heading H5H [Also in Division B2] A sheet-like resistance heating element comprises a plastics film with a surface layer of carbon black particles firmly attached without an applied binder, and the individual particles or agglomerates being substantially un-enveloped by electrically insulating material, the layer having a surface resistance of less than 1000 ohms per square, preferably 10-100 ohms per square. The film surface is treated by a solvent or swelling agent which is subsequently removed by heating, and the particles are applied dispersed in the solvent or subsequently. The plastics film is preferably of a stretched polyethylene terephthalate or polypropylene with a 10 to 50 Á thickness. Other polyester or plastics films may be used, including polyvinyl chloride, polyamide and copolymers of isophthalic acid/ terephthalic acid. The heating element surface may be covered with a water-impermeable plastics film. Terminal zones on the resistance layer are made by applying a conductive lacquer including silver particles. A thermocouple arrangement is provided. Copper-stranded lead wires are attached to the terminal zones by silvered copper rivets. Suitable solvents and swelling agents are detailed. The heating elements are used for heating floors, walls, ceilings, tents, halls, pipes, soil, bridges, roads, garage entrances, sports fields, warming cupboards, deck chairs, cushions, carpets, car seats, clothing and in panel heaters.