Helium shielding gas

Helium is a light shielding gas that makes a hotter and more stable arc than pure argon. This gives you deeper penetration and lets you weld thicker materials better. The higher price and greater flow tendency of the gas are the downside – you need more gas volume to cover the weld zone cleanly. For aluminum and stainless steel, a helium proportion in argon is common when you want to bring more heat into the weld. Note that the arc gets hotter, so don't blindly go to maximum power, otherwise the material will burn away.