Gases guide
Welding Gases Explained: Argon, Mixes, CO2 and Bottles
Gas is half of MIG and all of TIG. This page decodes the cylinder wall: what each gas does, what it costs in Australia, and which mistakes ruin welds and equipment.
The gases and their jobs
| Gas | Used for | Flow | Character |
|---|---|---|---|
| Pure argon | TIG all; MIG ally/stainless | 8–12 L/min | clean, quiet arc |
| Argon-CO2 92/8 | MIG steel — the AU default | 12–15 L/min | stable, low spatter |
| Argon-CO2 80/20 | MIG thicker steel | 12–15 L/min | stiffer, deeper |
| 100% CO2 | budget MIG on thick | 15–20 L/min | penetrative, spattery |
| Argon-helium | thick aluminium | 12–18 L/min | hotter arc, pricier |
Bottles: sizes, hire and swaps
Common Australian argon-family cylinder sizes by free-gas volume: D ≈ 1,700–2,000 L, E ≈ 4,000–4,600 L, G ≈ 8,700–10,200 L — read the label, since volumes vary by supplier and fill pressure. Refills run roughly $100–$140 (D) and $150–$200 (G) across capitals. Hire suits daily trade; swap-and-own suits hobbyists who'd pay more in annual hire than refills. Estimate your litres-per-job with our gas flow calculator before choosing.
The never-rules
- Never run CO2-containing mix on TIG — it destroys tungsten and the arc
- Never run a steel mix on aluminium — porosity and a grey, weak weld
- Never guess flow: too low = porosity, too high = turbulent shield pulling air in
- Never store cylinders unchained or on their side in a vehicle without restraint
Frequently asked questions
What gas do I need for MIG welding?
For MIG welding mild steel in Australia use an argon–CO2 mix — 92/8 (Argoshield-style) is the standard. 100% CO2 is the budget alternative with more spatter. For MIG on aluminium or stainless you need straight argon or a specialist mix respectively.
What is pure argon used for in welding?
Pure argon is used for TIG everything; MIG aluminium and stainless, typically at 8–12 L/min TIG. The default TIG shield; also the base of most mixes
What is argon-CO2 mix used for in welding?
Argon-co2 mix is used for MIG on steel (Argoshield-family 92/8 to 80/20), typically at 12–15 L/min. More CO2 = deeper penetration, more spatter; 92/8 is the Australian hobby standard
What is 100% CO2 used for in welding?
100% co2 is used for cheap MIG on thicker steel, typically at 15–20 L/min. Dirtier but cheap and penetrative; fine for farm repairs
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