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What is the most common shielding gas mix for MIG welding mild steel?

75% argon, 25% CO2, often called C-25.

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  1. 75% carbon dioxide, 25% argon
  2. 100% helium
  3. 75% argon, 25% carbon dioxide ✔

Why: The 75/25 argon and CO2 blend is the all-purpose choice for carbon steel. It runs smooth with little spatter.

Huh, didn't know that: Miller calls this mix C-25 and says it gives good arc characteristics.

The dad joke
Argon walks into a bar. Nothing happens, because it is inert.
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References

Answer: 75% argon, 25% carbon dioxide. The 75/25 argon and CO2 blend is the all-purpose choice for carbon steel. It runs smooth with little spatter.

  1. Understanding the Basics of MIG Welding for Mild Steel (Miller) www.millerwelds.com/en-us/resources/knowledge-hub/mig-welding/how-to/understanding-the-basics-of-mig-welding-for-mild-steel
    75% Argon / 25% Carbon Dioxide Blend (also called 75/25 or C-25)
    Checked 2026-10-10.
  2. Best Gas for MIG in DIY (Miller) www.millerwelds.com/en-us/resources/knowledge-hub/mig-welding/how-to/what-type-of-gas-is-best-for-mig-welding-in-diy-applications
    C-25 gas produces minimal spatter and provides good arc characteristics.
    Checked 2026-10-10.

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Trades & ShopWhat shielding gas is most common for MIG welding aluminum?Trades & ShopWhich argon and CO2 mix does Miller say works well for MIG welding stainless steel?Trades & ShopCompared with 75/25 argon and CO2, what does 100% CO2 shielding gas tend to give?

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