TECHNOLOGY FOCUS - ELECTRONICS - Preferred Method: The method comprises: moving the carbon-containing substrate through the electric arc to heat the substrate to a substrate surface temperature up to 4200K; and moving the carbon-containing substrate through the electric arc so as to remove substantially non-graphitic carbon from the substrate. The method includes: moving the substrate at a substantially steady speed through the arc; moving the substrate through the arc in steps; tensioning the substrate against the anode (or the cathode) of the electrodes; moving the substrate (or the arc) at a speed such that the substrate has a residence time in the arc of less than 3 seconds; moving the substrate at a speed of more than 3 mm/second; flushing a gas through the reaction chamber which contains sufficient oxygen to react with other species without oxidizing the fibers enough to substantially damage them during cool down; directing a flow of gas to cool one or both of the electrodes and/or the substrate; and directing a flow of gas onto the substrate after it has passed through the arc to cool the substrate and/or clear it of carbon vapor. The arc current is set at a level which vaporizes: a major fraction of non-graphitic carbon and no more than a minor fraction graphitic carbon of the substrate; and a substantial part of non-graphitic carbon of the substrate substantially without structurally damaging a graphitic part of the substrate. The arc has a current of: 10 to below 16 Amps; or above 16 to 20 Amps. The arc is between electrodes having an inter electrode gap of: less than 5 mm or above 8 mm; 2-5 mm; or 8-12 mm. In the method, at least one electrode is a carbon containing electrode. The arc current has rms voltage ripple of greater than 1 volt and/or current ripple of greater than 0.5 Amps. Preferred Components: The substrate is: composed of carbon fibers; a tape or belt woven from carbon fibers; or a paper of carbon fibers. The electrodes and the substrate have a carbon purity in excess of 95 (preferably 99)%.