It appears that the origins of a soldering gun can be tracked back all the way to 1620 when an unnamed Englishman invented an early version of a soldering iron which used a heated copper tube with a lead-coated tip. The earliest documentation we could find for this particular device shows how to use and maintain it and warns against overuse, especially on work made from gold, silver or lead. As welding emerged as means for joining metal in the late 1800's newer versions of the solder iron were developed. Manufacturers started designing units that could heat up faster then execute high heat more efficiently while some units are water cooled not only reducing the risks associated with overheating but keeping expensive equipment running at optimal efficiency too.