I'm interested in knowing whether or not submerged welding can be done in fluids other than water, specifically mineral oil in this case. The reason I want to know is that I'm looking into designing an extrusion 3D printer for metals that works on the same principle as stick welding, like these ones:
However, I don't want the metal to oxidize, and the machines in these examples produced very poor surface quality due to the metal overheating and melting. I know that the oxidization could be prevented by surrounding the entire print in an inert gas, like argon, carbon dioxide, or sulfur hexafluoride, but I wanted something that would be easier to recycle without getting contaminated, plus a fluid would help to keep the print cool. Water isn't an option because it rusts metal and its conductivity makes it dangerous to use with electricity, so mineral oil seemed like the best option, as it is also used to cool transformers.
My major concern with using oils of this kind is, obviously, that they are flammable when heated to high temperatures in the presence of oxygen, so for this question I'm assuming the welding is taking place either in an airtight box (but expandable to account for the oil evaporating), or in a swimming pool full of mineral oil big enough for the heat to dissipate into safely. I was also wondering if the oil might decompose into toxic chemicals at welding temperatures or introduce unwanted inclusions or contaminants into the weld. Anything you can tell me would be helpful. Thanks.