Board Thread:General Discussion/@comment-110.146.149.161-20150813074512/@comment-25396609-20150908001726

actually, it is a slightly altered form of air.

pure air can be used for cutting as well, A friend of mine was screwing around with an air compressor some time ago and managed to rig up the nozzle for a garden hose to it in such a way that he was able to carve his name on a concrete block with the air stream.