Most beginners set their gas flow by feel—which is code for “guessing.” For aluminum, you usually need about 15 to 20 cubic feet per hour. Too little gas, and your weld turns black and crumbly. Too much gas, and you’re literally throwing money into the air while creating a mini tornado in your shop.
Here’s the kicker: gas flow is affected by your shop’s air currents. A ceiling fan can ruin your entire afternoon. I once saw a welder chase a wandering gas cloud around his garage like a cat chasing a laser pointer. Don’t be that guy—close the window.
Breaking the No CO₂ Rule (PLEASE Read)
You might be tempted to use carbon dioxide (CO₂) instead of argon. Don’t. CO₂ is great for steel welding—it’s cheap and chunky. But on aluminum, CO₂ reacts and creates a weld that looks like burnt popcorn with cavities. I have seen a friend try this. He called the result “modern art.” I called it “a cry for help.”
In fact, never, ever use pure CO₂ on aluminum. Unless you enjoy welding lumps of disappointment.
How To Master Gas Welding Aluminum - Redback Aviation
