A Beginner’s Guide to Shielding Gas Mixes and Argon CO2 Mix for MIG Welding

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Welding Buddy Experts

April 30, 2021
argon co2 mix for mig welding

Are you a beginner in metal inert gas (MIG) welding or a hobbyist trying to figure out how to weld and produce a smooth output? Do you often find yourself a little disappointed because the final product you got is a material filled with pores and spatters? Be a little kinder to yourself if you’ve only had a few tries and start reading this article, as this may just be the solution and information you need. 

This article will discuss the different shielding gases you can use so that your welding creation will be just as you imagined. But before we get into that, let us first talk about something a bit familiar—the different welding challenges.

What Is Shielding Gas? 

Shielding gas, from the name itself, acts as the shield of the welding gas so that no other material from the outside environment can penetrate the weld. If you look at the flare coming out of the MIG gun, the flare follows a straight path instead of looking like scattered smoke. The shielding gas makes this linear path possible. 

Welding defects such as porosity, lack or incomplete penetration, cracks, spatters, and overlaps will not happen to your material with the suitable shielding gas. This perfection happens because no other gases such as oxygen, hydrogen, or nitrogen enter the weld. 

Aside from inhibiting defects, using the suitable shielding gas allows for deeper penetration, arc stability, and easy bending of the material you are welding. You will have an end product that looks clean on the outside and solid on the inside. 

Gases Used for MIG Welding

In MIG welding, several gases can be mixed to create a reliable shield. These gases are as follows: 

  1. Argon
  2. Carbon dioxide
  3. Nitrogen
  4. Oxygen 
  5. Helium

Argon gas for MIG welding is the most commonly used and mixed gas among these gases. Argon is a type of inert gas that ensures reaction to other gases resulting in welding defects does not occur. Together with its nonreaction to other gases, argon fulfills shield welding needs. 

Argon can also be used independently, although it is not advisable. The argon mixture for MIG welding is the best choice. You will often see argon gas for MIG welding in all the shielding gas mixes below. 

Best Argon Mix for MIG Welding

In this list is the best argon mix for MIG welding. You can base on your experience which among the combinations works best for you, or you can ask gas sellers' input upon purchasing the gases. They are experts in this field. 

  1. 100% Argon

Using 100% argon for your welding is possible but not advisable. Argon may be the gas you have the most supply of in your welding room because you always use it. When it is the only gas left on the shelf and you are in a rush to finish your welding, you can use 100% argon.

Benefits of 100% Argon

The only advantage you will get from using pure argon mixture for MIG welding is its readiness to be used anytime. 

Disadvantages of 100% Argon 

While it is convenient to use 100% argon, you wouldn’t like the outcome. Using 100% argon will create an unstable arc because the arc voltage and power are reduced with only argon as the present gas. 

Also, a weld pool will not be as melted as in other argon mixes. As a result, deeper penetration will not be possible. With the lesser malleability of the metal material, it won't be easy to bend and twist the material. 

These disadvantages will be more pronounced if you try to weld steel with 100% argon. 

  1. Argon CO2 Mix for MIG Welding 

Before we go into using argon and carbon dioxide mixture, you should know that carbon dioxide can be used independently, allowing deep penetration even of thick materials. You might ask which is better: CO2 vs. argon MIG welding. The answer is the mixture of argon and carbon dioxide is the best. 

Benefits of Argon and CO2 mix

Get the correct measurement of 75% to 95% of argon and 5% to 25% of carbon dioxide. The mixture will cover the following areas for improving pure argon and pure carbon dioxide welding.

  • There will be fewer spatters and undercuts than with pure carbon dioxide. You can expect a smooth output.
  • The arc will be more stable compared to using pure carbon dioxide.
  • The weld pool will be melted better, allowing deeper penetration. 
  • The argon and carbon dioxide mixture will allow just the right amount of heat for material bending and twisting. 

With all these benefits, CO2 vs. argon MIG welding is not a question, but knowing how to use them together matters more.

Disadvantages of Argon and Carbon Dioxide Mix

The only disadvantage of using the argon–carbon dioxide mixture is the cost. For hobbyists, the price may not be as low as other gases, but the experience can be worth spending on. For more prominent companies with financial resources, the argon–carbon dioxide mixture is a profitable investment. 

  1. Argon + Helium Mix

If you are welding thick materials, a combination of 25% to 75% helium and 25% to 75% of argon will do the work. 

Benefits of Argon + Helium Mix

The ratio of argon to helium in the mixture you will create will determine the depth of the penetration, weld travel speed, and bead width. With helium's presence, your welding work will be faster because of a hotter arc. You can melt even thick steel at a quicker rate with helium. 

Disadvantages of Argon + Helium Mix

The speed of welding brought by helium comes at a price. This mix will cost you a bit more money, but if your priority is speed over the cost, then this is the best mix for you. 

  1. Trimix — 90% Helium, 7.5% Argon, and 2.5% CO2

Altogether, the three materials create the best weld for stainless steel.

Benefits of Trimix

As individual welding gases, helium, argon, and carbon dioxide can create a quality weld. Helium is best for thick materials. Carbon dioxide allows deep penetration, and argon is the inert gas that creates a better shield. You can expect a smoother end product with a 90% helium, 7.5% argon, and 2.5% carbon dioxide mixture. 

Disadvantages of Trimix

The trimix is another expensive choice for MIG welding shield gas. Still, the investment is worth it because of the advantages it brings. Suppose you’re aiming for an outturn that will make you feel proud because it is visually pleasing and sturdy. In that case, the trimix should be your go-to combination. 

  1. Argon and Oxygen 

Oxygen is one of the gases that cause spatters and pores on your weld. Still, if used in the right amount, oxygen can bring advantages to your welding. 

Benefits of Argon and Oxygen Mix

Adding 2% oxygen to argon allows a faster weld and more stable arc for TIG welding. Weld puddle tension is also lessened, allowing better creation of a weld pool. 

Disadvantages of Argon and Oxygen Mix

Note that you should not use this kind of mixture for copper, magnesium, and aluminum materials. 

  1. Argon and Nitrogen

Another gas in the atmosphere which creates porosity on the weld area is nitrogen. Still, with the right mixture of argon, you can expect many advantages. 

Benefits of Argon and Nitrogen Mix

When added in the right amount, you can reap benefits like arc enhancement, deeper penetration, resistance to corrosion, and prevention of nitrogen loss to the material being welded.

Disadvantages of Argon and Nitrogen Mix

Too much nitrogen can cause brittleness of the material being welded as well as porosity. 


The solution to your weld spatter and porosity challenges are now within reach. Now that you know how shield gases help you achieve an end product free from spatters and pores, it is time to try them for yourself. Just make sure to follow safety welding protocols around gases. Be especially mindful of the dangers of argon since it is the gas you will be using the most. 

If you are on your way to the shield gas store to get your mix, feel free to send us a message or comment below to share your experience! We’ll be glad to hear from you. 

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