Copper starts to break down once its temperature exceeds 200 degrees. Keeping the gas nozzle clean is an important measure for several reasons. A gas nozzle with threads dirty from spatter buildup or oxidization will allow for significantly decreased metal to metal (copper to copper) contact when the gas nozzle is threaded back into the torch. This reduced contact with the copper front of the water-cooled nozzle will decrease the amount of cooling on the gas nozzle. More importantly, however, is the fact that the lack of contact will cause resistance heating. Without a clean connection, the electrical current that passes through the gap between the threads of the gas nozzle and water-cooled nozzle will turn into heat, causing the front of the torch to be preheated. Further, a torch can be overheated by not threading a copper gas nozzle all the way up so that the copper gas nozzle is not seated on the water-cooled nozzle’s copper front; resistance heating will also occur if the gas nozzle is not seated and snug tight. Resistance heating is a great threat to the life of the torch, causing consumables to be used up prematurely, and even causing damage to the torch itself.