If you are new to MIG welding, you might be wondering “What Gas is Used for MIG Welding?” and why it’s needed. Gas plays a big role in making strong and clean welds.
In this post, I’ll explain:
- What MIG welding gas is?
- Types of Shielding Gas
- How much Quantity of shielding gas required
- Which gases are used, and how to choose the right one.
Lets start with some basic information!
What is MIG Welding Gas?
MIG welding gas is the gas used to protect the weld while you are working. It keeps the weld safe from the air so it doesn’t get weak or full of holes. This gas is also called shielding gas, because it creates a shield around the weld to keep it clean and strong.
What Gas is Used for MIG Welding?
MIG welding uses shielding gas. This gas protects the molten metal from air and helps the weld stay strong and clean. Without gas, the weld would get dirty and weak.
Common Gases for MIG Welding
Here are the main gases people use for MIG welding:
Argon (Ar)
- Pure argon is mostly used for welding non-ferrous metals like aluminum and copper.
- It makes the weld look smooth and shiny.
Carbon Dioxide (CO₂)
- CO₂ is often used for welding steel.
- It’s cheap and works well, but the weld may have more spatter.
Argon + CO₂ Mix
- This is the most common choice for welding steel.
- Usually, the mix is 75% argon and 25% CO₂, but it can vary.
- It gives a cleaner weld with less spatter than pure CO₂.
Other Argon Mixes
- Sometimes, small amounts of oxygen or helium are added.
- These mixes can improve arc stability or penetration.
How much gas do you need for MIG Welding?
One question I get a lot is: “How much gas do I need for MIG welding?” This is really important because the right amount keeps your weld strong and clean. Too little gas, and your weld gets messy. Too much gas, and you waste money.
| Gas Type | Metal Type | Flow Rate (CFH) | Bottle Size (lb) | Approx. Duration (hours) |
|---|---|---|---|---|
| CO₂ | Steel | 20 | 20 | 4–5 |
| Argon-CO₂ Mix | Steel | 25 | 40 | 8–10 |
| Argon | Aluminum | 30 | 40 | 7–8 |
| Argon-Helium Mix | Aluminum | 35 | 40 | 6–7 |
Gas Flow Rate
When we talk about “how much gas,” we usually mean the flow rate — how fast the gas comes out of the nozzle.
- For most MIG welding on steel, I use 20–25 cubic feet per hour (CFH).
- For aluminum, because it’s lighter and more sensitive, I usually go around 30–35 CFH.
Think of it like a gentle wind blowing over your weld. Too weak, the wind doesn’t protect the weld. Too strong, it blows the molten metal around.
Gas Bottle Size
How long your bottle lasts depends on its size and your flow rate:
- A 20 lb CO₂ bottle lasts about 4–5 hours at 20 CFH.
- A 40 lb Argon-CO₂ mix bottle can last 8–10 hours at 25 CFH.
Of course, this changes if your flow rate or welding time changes.
My Tip: I always check my gas flow before starting. I’ve ruined a few welds by forgetting this! It’s easy just watch the regulator and listen to the hiss. You want a steady, smooth flow, not a roar.
Types of Shielding Gas for MIG Welding
Shielding gas is a gas that protects your weld from air. When metal melts during welding, it reacts with oxygen and nitrogen in the air. This can make your weld weak or messy. Shielding gas keeps the air away so your weld is clean and strong.
Common Types of Shielding Gas for MIG Welding
When it comes to MIG welding, choosing the right shielding gas is very important. Shielding gas protects your weld from air, which can make the metal weak or messy. Over the years, I’ve used several types of gases, and each one has its own purpose depending on the metal and welding situation.
Argon (Ar)
Argon is mostly used for welding aluminum and copper. It creates a smooth, shiny weld and works best with thin metals. When I started welding aluminum, I learned quickly that argon is the only gas that gives a clean finish. It makes the arc steady and easy to control, which is very helpful for beginners.
Carbon Dioxide (CO₂)
CO₂ is very common for welding steel. It’s cheap and easy to find, which makes it a popular choice for many welders. I used CO₂ a lot when I was starting with steel welding. The only downside is that it can cause more spatter compared to argon or argon mixes. Even so, it works fine and is a good option if you are on a budget.
Argon + CO₂ Mix
The argon and CO₂ mix is the most common choice for steel welding. Usually, it contains about 75% argon and 25% CO₂, although other ratios exist. Using this mix gives a cleaner weld with less spatter than pure CO₂. I switched to this mix after a while and noticed my welds became much smoother and stronger. It’s a great all-around choice for steel.
Argon + Oxygen Mix
Sometimes a small amount of oxygen (usually 1–5%) is added to argon. This helps stabilize the arc and makes welding steel easier, especially for beginners. I’ve found that using a tiny bit of oxygen helps when welding thin steel sheets. It improves penetration and reduces defects, making the process more predictable.
Argon + Helium Mix
Argon and helium mixes are used for aluminum and stainless steel. Adding helium helps get deeper penetration and allows faster welding. It’s a bit more expensive, but for thicker metals, it’s worth the cost. I use this mix when I need a strong, clean weld on aluminum or stainless steel projects.
Best Gas for MIG Welding (Based on Material)
Choosing the right gas for MIG welding depends mostly on the type of metal you are welding. Using the correct gas makes your weld stronger, cleaner, and easier to work with. Over my years as a welder, I’ve learned which gases work best for different materials.
Steel
For steel, the most common gases are CO₂ or an argon-CO₂ mix. Pure CO₂ is cheap and works well, but it can cause more spatter. If you want smoother and cleaner welds, I recommend the argon-CO₂ mix, usually around 75% argon and 25% CO₂. I use this mix almost all the time when welding steel because it reduces spatter and makes the weld stronger.
Aluminum
When welding aluminum, pure argon is the best choice. Aluminum is sensitive to air, so argon protects the weld and creates a smooth, shiny finish. I learned the hard way that using CO₂ or other mixes on aluminum doesn’t work the weld becomes messy and weak. Always stick with argon for aluminum.
Stainless Steel
For stainless steel, an argon-helium mix or an argon-CO₂ mix works best. Helium helps get deeper penetration and faster welding. I usually use a small argon-helium mix for thicker stainless steel pieces. It’s more expensive, but the results are much cleaner and stronger compared to CO₂ alone.
Copper and Other Non-Ferrous Metals
For metals like copper, pure argon is also recommended. It provides a stable arc and prevents contamination from air. Non-ferrous metals are sensitive, so protecting the weld with the right gas is very important.
Read More: What Is Underwater Welding? Salary, Death Rates, Accidents and Training
Some other Gases you can use for Mig Welding
Besides the common gases like argon, CO₂, and their mixes, there are a few other gases that welders sometimes use for specific purposes. These gases can help improve weld quality, arc stability, or penetration, depending on the material and project.
Oxygen (O₂)
A very small amount of oxygen, usually 1–5%, can be added to argon when welding steel. This helps stabilize the arc and improves penetration. I’ve used this mix when welding thin steel sheets, and it makes the process much smoother. Just remember, too much oxygen can weaken the weld, so only a tiny amount is needed.
Helium (He)
Helium is often mixed with argon for aluminum and stainless steel welding. Helium increases heat and penetration, which allows faster welding and stronger joints. I usually use an argon-helium mix for thicker aluminum projects. It’s more expensive, but it’s worth it if you want a strong, clean weld.
Nitrogen (N₂) and Hydrogen (H₂)
These gases are less common but sometimes added in tiny amounts to argon for specialty metals or stainless steel. They can help improve arc stability or prevent discoloration. I don’t use these often, but some professional welders prefer them for specific high-quality welding jobs.
Important Note
While argon, CO₂, and their mixes are the most common, these other gases oxygen, helium, nitrogen, and hydrogen can be useful for improving your welds in certain situations. Choosing the right gas depends on the metal, thickness, and type of weld you need.
Read more: Top 10 Risks of Underwater Welding
How to Choose the Right MIG Shielding Gas?
The correct gas can make your welds stronger, cleaner, and easier to do. Over the years, I’ve learned that picking the wrong gas can ruin a weld, so it’s worth taking the time to choose wisely.
Consider the Metal Type
The first thing to think about is what metal you are welding. Different metals need different gases:
- Steel: CO₂ or an argon-CO₂ mix
- Aluminum: Pure argon
- Stainless steel: Argon-helium or argon-CO₂ mix
- Copper or other non-ferrous metals: Pure argon
I always start by asking myself: “What metal am I working with?” Once you know this, the gas options become much clearer.
Consider Metal Thickness
The thickness of the metal also matters. Thicker metals need gases that give deeper penetration, like helium mixes for aluminum or stainless steel. Thin metals need gases that are gentle and stable, like pure argon. I’ve ruined thin metal sheets before by using a gas mix meant for thick materials — the weld burned through!
Consider Welding Position and Quality
Your welding position and the quality you want also affect gas choice. Some gases, like CO₂, create more spatter, which is okay for some jobs but not ideal for visible or precise welds. If you want a smooth, clean weld, an argon-CO₂ mix or pure argon is better.
Consider Your Budget
Some gases are more expensive than others. Pure argon or argon-helium mixes cost more than CO₂. When I started welding, I used CO₂ for steel to save money, but later switched to an argon-CO₂ mix because it improved my weld quality. Think about your budget versus the quality you need.
Summary
To choose the right MIG shielding gas:
- Know the metal type
- Consider metal thickness
- Think about weld quality and position
- Factor in your budget
Following these steps will make your welding easier and give you stronger, cleaner welds every time.
Where to buy gas for MIG welding?
Once you know which shielding gas to use, the next step is finding it. Buying the right gas is important because using poor-quality gas can affect your welds. Over the years, I’ve learned a few good places to get MIG welding gas.
Local Welding Supply Stores
One of the easiest places to start is a local welding supply store. These stores usually carry a wide range of gases like CO₂, argon, and mixes. You can also get help from staff if you’re not sure which gas to pick. I often go to my local welding shop because I can check the bottles in person and get advice from experienced staff.
Industrial Gas Suppliers
Many industrial gas companies sell MIG welding gases in bulk. Companies like Airgas, Praxair, or Linde provide cylinders for businesses and hobbyists. They usually offer delivery and exchange programs, which is convenient if you weld a lot. I’ve used these suppliers when I needed large bottles for long projects.
Online Retailers
You can also buy welding gases from online stores. Websites like Amazon, eBay, or specialized welding sites often sell small gas cylinders or refill services. This is handy if you don’t have a local supplier nearby. Just make sure the gas is certified and safe for welding.
Safety and Regulations
Remember, welding gases are under pressure and flammable in some cases. Always buy from reputable suppliers and follow safety guidelines for storing and using the gas. Poor-quality or damaged bottles can be dangerous, so don’t take shortcuts.
Summary
In short, you can buy MIG welding gas from:
- Local welding supply stores – convenient and personal advice
- Industrial gas suppliers – for bulk or delivery
- Online retailers – convenient if local options are limited
Frequently Asked Questions
Do all MIG welders need gas?
Not all MIG welders need gas. There are two types of MIG welding: gas-shielded and flux-cored. Gas-shielded MIG welding uses shielding gas like argon or CO₂ to protect the weld, giving a clean finish. Flux-cored MIG welding, on the other hand, uses a special wire with flux inside, so no external gas is needed. I’ve used both types gas-shielded is cleaner, but flux-cored works well outdoors or in windy conditions where gas could blow away.
Can I use CO₂ only for MIG welding?
Yes, you can use CO₂ only for MIG welding, but it has pros and cons. CO₂ is cheap and easy to find, and it works well for welding steel. However, it produces more spatter and a rougher weld compared to an argon-CO₂ mix. I’ve used pure CO₂ when I wanted a budget-friendly option, but for smoother, cleaner welds, I prefer the argon-CO₂ mix. CO₂ alone is fine for beginners or outdoor work, but if quality matters, consider a gas mix.
What happens if I weld without shielding gas?
If you weld without shielding gas, your weld will likely be weak, messy, and full of defects. Air contains oxygen and nitrogen, which react with the molten metal, causing porosity, spatter, and poor penetration. I’ve tried welding without gas once the weld looked rough and wasn’t strong at all. Using the proper shielding gas protects the metal and gives a clean, strong, and reliable weld, so skipping it is never a good idea.
Which Mig Gas is Best for Mig Welding?
The best MIG gas depends on the metal you’re welding. For steel, an argon-CO₂ mix is ideal because it gives clean, smooth welds with minimal spatter. For aluminum or copper, pure argon works best, providing a stable arc and shiny finish. I’ve used both over the years, and choosing the right gas makes welding easier, faster, and stronger. For stainless steel or thicker metals, an argon-helium mix can give deeper penetration and better results. Always pick the gas based on the metal and thickness.
What is shielding gas for MIG welding?
Shielding gas is the gas used in MIG welding to protect the molten metal from air. When metal melts, it reacts with oxygen and nitrogen in the air, which can make the weld weak, full of holes, or messy. I’ve learned that using the right shielding gas keeps the weld clean, strong, and smooth. Common shielding gases include argon, CO₂, and their mixes, and choosing the right one depends on the type of metal and thickness. Without shielding gas, your weld quality drops significantly.
Conclusion
Choosing the right MIG welding gas is important for strong, clean welds. Different metals need different gases, and the right flow rate and type make welding easier and safer. Whether you use CO₂, argon, or a mix, always pick the gas based on the metal, thickness, and quality you want. Using the correct gas will save time, reduce spatter, and give professional-looking results every time.
Hello Everyone! I’m Seo Jun, a professional welder with over 7 years of hands on practical experience in South Korea. Right Now, working in Seakor Corp. Ltd. I created myweldingtips.com to share real-life welding tips, safety advice, and techniques. My goal is to help others learn faster and work smarter through practical, easy-to-understand welding guides. Contact me
