Shielding Gases
https://www.bernardwelds.com/mig-welding-shielding-gas-basics-p152080#.XsUmZh-YU5k
- Argon is best, but only 1% of earths atmosphere, is typically produced by Liquid Air Distillation
- Nitrogen should work for most uses, easily made small scale via Pressure Swing Absorbtion , in one stage is fine, but can be ultra pure if two stages are used
- Also can supposedly add hydrogen oxygen and carbon dioxide as enhancers (ie more temperature, adjust oxidation/reactions etc)