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How to Choose the Right Welding Gas

The Voice: Hey, Kevin. Why are you looking at us like that?

Kevin Caron: Because somebody's sleeping out there.

I've had several questions recently from my YouTube video subscribers about shielding gas: Why do I have to use two different bottles - one for TIG and one for MIG? Why can't I use the same gas on different machines? Why do I need to use different gases to do different processes or work on different metal?

Let's talk about shielding gas again.

This cute little bottle is one I bought awhile ago when I was working with my Miller 251 MIG welder on a contemporary art sculpture made out of stainless steel.

This is actually a tri-mix, so it's argon, carbon dioxide, and helium. They added that helium in there because it helps with penetration and also cuts down on porosity. You know how much I hate porosity.

Normally the percentage of mix would be written on here, but this poor little bottle is so old that the paint marks have faded away to nothing.

Wherever you get your bottles filled, tell them you want tri-mix (argon, carbon dioxide, helium) if you're going to work with stainless, do MIG welding, or aluminum MIG welding. It's a great mix for doing this kind of work with a MIG.

Now, with the TIG welder: straight argon, nothing else. That's all you need. Because of the way the TIG process works, you can get away with just using this gas and you change your filler rod. Whether it's stainless or aluminum, you can get away with the same gas.

But when you use your MIG equipment and you're just doing steel, then you'll want to use argon and carbon dioxide, commonly called MIG gas. It's a two-mix; a two-part mix as opposed to the three-part mix. This works the best with just plain old steel.

There are many different kinds of mixes, different percentages. It all depends on what you're doing and what you want to get out of the weld. You can add a little helium like in the tri-mix, get a little better penetration, little less porosity, but there's a drawback - with the helium, it takes a little more power. It's a little hotter, so you have a little more problem with burn-through. You've got to be a more careful with what you're doing. You'll want to use the tri-mix with a thicker metal rather than a thinner metal.

There are so many different variations on it, whether it's just a straight bottle like argon or a dual mix like the argon and carbon dioxide, or tri-mix. Then there are all the different percentages, whether it's 20 percent argon and 20 percent of this and 90 percent of that; it gets incredibly complex.

That's why we have the guys at the gas store, where they fill the bottles. They can help you with that. And the guys at the welding store can give you advice on the welding.

Or, do like I did: Good old Wikipedia. Just type in "shielding gas," or "welding gas," or "inert gas." You get tons of information. You've got the world's biggest library sitting right on your desktop. Jump out there, take a look. It answers a lot of questions for you.

Learning about the various gases makes you a better welder, gives you a better job, a better finish, you spend less money because you get the right kind of gas the first time.

Hope that helps. We'll see you again.

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