Abstract: This invention discloses paint compositions and the preparation of paint compositions which can be spread and dried to give electrically conductive films. The paint compositions contain colloidal carbon particles. The graphite is wet ground and this is found to give a particular shape to the resulting particles and a particle size distribution such that the dried conductive films have a low resistivity in the range of about 0.1 to 10 ohms/square. Such films produce useful heat outputs when relatively low voltage currents are passed through them and so they are suitable for application to the walls of a building for use as a central heating system.