Welding Tips and Tricks

I'm new to tig welding and I just started to weld aluminium but I have a contamination issue.
I was welding some alloy pipe with no problems until i ran out of gas so I got new gas and ever since then I have a big contamination problem. I bought another bottle and with this new bottle it welds fine again. Is there any way to test to see if i have pure argon or some mixture or did I miss something else? Both bottles have the same label on them. I attached a picture of 2 welds done with the only difference being the gas.

Do you crack the bottle valve before you attach the regulator? It's possible there was a bit of contamination in the bottle valve that prevented or reduced the flow. If you watch the flow meter while the gas valve on the welder is open you could confirm whether or not there is adequate flow.
To answer your question, argon is inert so there aren't many ways to test for it. Spectrosopy is probably the easiest way, but even that requires access to a rather expensive piece of equipment.

When I get a new bottle I always put the regulator on before I open it but before I start welding I always check the flow rate and run the gas through the welder for about 10 seconds. I'm assuming I should not use the bad bottle and just empty it. Now that I know I can't prove the gas is bad it will be hard for me to get my money back for the gas.

davidgtr wrote: I'm assuming I should not use the bad bottle and just empty it. Now that I know I can't prove the gas is bad it will be hard for me to get my money back for the gas.

I would think if you took it back where you bought it and explained what happened, they'd be anxious to either exchange it or analyze it to figure out how they made a mistake. There's lots of gases that go boom if they're exposed to the wrong environment. I think any place that supplies specialty gases in addition to industrial gases, like Airgas or Praxair, would have analytic capability.

Where I buy my gas also will refund me any unused gas remaining within the bottle. There have been times I needed full bottle but had less than a quarter remaining, so replacing it was in order. But not wanting to waste the gas I paid for, I inquired. Worked perfectly in my favor as was their standard practice (so I didn’t feel so special, but still appreciated it)