Coldheat is an American company that develops and markets special soldering iron called ColdHeat. ColdHeat iron product was review at ePanorama.net eariler. The secret of that product is a proprietary graphite-like compound called Athalite. The tip of this apparatus is split into two sections that completes an electrical circuit when something of low resistance is placed across the tip; e.g. solder. With a current flowing, the resistance of both the solder and the tip produces heat that allows you to do soldering.
The original iron is powered by 4 ordinary AA (LR6) alkaline batteries. The device works by running a high current (by electronic standards) through the tip and there is considerable voltage on the tip as well. Howstuffworks ColdHeat article describes the soldering iron operation and Wikipedia also has some technical information.
I own one ColdHeat soldering iron. I have occasionally used that. That tool is practically useless for fine electronics circuit board soldering. It lacks temperature control and it is too easy to destroy sensitive electronics circuit with it. When not in contact with a joint the split tip has 6 volts, which is enough to cause lots of damage because a forward-biased p-n junction may be destroyed by less than 1V applied across it (unless current is limited to low value). There is also tiny transient voltage when the tool is applied or removed.
That tool is useful for occasional soldering of items that are not sensitive to the voltages and current the ColdHeat soldering iron generates. I have found that this soldering iron works quite well for soldering wires to some connectors. For example for soldering and repairing audio/video cables on the field. It is fast and easy when you just need to make few solder joints. When I need to make many solder joints, I prefer to use a temperature controlled normal soldering iron.
