5 Essential Gasless MIG Welding Tips

5 Essential Gasless Mig Welding Tips | Welder’s Choice

Gasless MIG welding is a popular welding technique that eliminates the need for an external shielding gas. This makes it ideal for projects that require mobility or working in tight spaces. In this article, we’ll explore the benefits of gasless MIG welding and how it differs from traditional MIG welding.

Remember when welding with gasless wire, the wire is a self-shielding wire and you don’t require a cylinder of welding gas.

A lot of beginners also prefer a gasless mig welder, as it’s easier and cheaper to get up and running. Gasless mig welding is one of the simplest ways for amateur welders to get professional results.

However, you still need to know what you’re doing.

Today, we’ll look at five simple tips to help beginners and experienced professionals alike get the most out of their gasless mig welders. But first, let’s get the basics out of the way.

stahlwerk mig 160 m

What is Gasless Mig Welding?

Gas vs Gasless mig welding?

Most welders use an external gas cylinder to shield their joints from oxygen in the air. This prevents holes within the weld bead, known as porosity, as well as excessive spatter. 

Instead of using an external gas cylinder, gasless welders use what’s known as ‘self-shielding wire’.

Essentially, this is a metal tube with a flux core. When the wire is heated, the flux burns and produces shielding gas. This prevents the welding joint from becoming oxidised or contaminated, without the need for an external gas cylinder. 

With that in mind, here are five tips for getting better results with a gasless mig welder.

  1. Select the Right Welding Polarity

The first thing you need to understand is that not all welders can be used with self-shielding wire. This is because welding torches need to have the right polarity for the type of wire you’re using.

Luckily, there are only three types of welding polarity to get your head around:

  • DC Straight – The electrical current flows from the electrode to the welding surface, creating significant heat on the welding surface.
  • DC Reverse – The electrical current flows from the welding surface to the electrode, concentrating the heat on the electrode itself.
  • Alternating – Here, the direction of the current alternates. This is primarily used for large industrial applications.

A gasless mig welder requires a welding gun with DC reverse polarity.

Using straight polarity with self-shielding wire will give you poor results. Typically, this will result in a large amount of splatter around the join. Naturally, you want your joints to look as clean as possible, so this is best avoided. 

Even worse, this can lead to structural issues, as wire splatters onto the wrong areas of your welding surface.

Most modern MIG welding machines can be set to either straight or reverse polarity. If your welder only offers straight polarity, it shouldn’t be used for gasless welding.

  1. Use your Gasless MIG Welder in a Well Ventilated Area

One of the great benefits of gasless welding is that it’s easier to work in small spaces when you don’t have an external gas cylinder. However, this creates certain problems of its own, especially as small spaces offer poor ventilation.

This is a big problem, as gasless welders produce quite a lot of fumes.

In the short term, this creates an unpleasant working environment. In the longer term, exposure to fumes can also cause health problems. As such, it’s vital to take precautions when working with a gasless welder.

The best way to prevent harm from welding fumes is to use a combination of local exhaust ventilation (LEV) and respiratory protective equipment (RPE). For instance, you might use a welding bench with air extraction, as well as an air fed welding helmet. You may also want to consider fume extraction at the source.  This could be on-torch extraction or with a portable fume extraction unit.



Air-fed welding helmets provide wearable ventilation.

  1. Use a Voltage Sensing Wire Feeder

Gasless mig welding is also popular for outdoor applications. For example, many farmers prefer gasless welders for repairing fences on their land, as they offer better portability. However, gasless welders don’t always work well with external generators.

Many portable generators provide constant current and variable voltage. This is not ideal for gasless welding, as different gauges of self-shielding wire require different currents.

To get around this problem, it’s best to use a voltage sensing wire feeder. This allows you to control the current going to your welding torch, even when you have a constant current supply.

Even when you’re not working in the field, voltage sensing wire feeders add an extra level of control over your welding arc. This helps you to create cleaner and more precise beads.

gasless mig welding


Combine gasless welding with a voltage sensitive wire feeder to control current in the field.

  1. Choose the Optimum Travel Speed and Angle

Switching from gas-shielded to self-shielding welding can be tricky for even the most seasoned professionals. As with anything, old habits are hard to break. This is equally true for adjusting your welding technique.

Because of their higher concentration of heat on the electrode, gas welders work best in a smaller range of attack angles. For vertical welding, 5-15 degrees is the optimal range of angels. For horizontal welding, this is 15-40 degrees.

Maintaining a constant travel speed is also vital when welding with self-shielding wire. Again, the high concentration of heat on the electrode can quickly cause puddling and create slag on your welding surface. To prevent this, it’s important to keep the torch moving

  1. Avoid Porosity and Worm Tracking

Self-shielding wire creates some problems which don’t occur with external gas shielding. This can be visual as well as structural. In either case, simply being aware of these is often enough to prevent them.

The first is porosity. Essentially, this is when pockets of the gas which is emitted by the flux get trapped in the joint. This results in weak points along your welding surface. 

Porosity can be prevented by thoroughly cleaning the surface before welding. This includes removing any dirt or grime from the surface. It’s also a good practice to keep your electrode extension under 3cm.

The second issue is worm tracking. This is the name given to marks created by flux gas on the surface of your welding joint. Typically, worm tracking won’t occur if you stick to the parameters listed by the manufacturer of the wire. 

If worm tracking does occur, it’s important to reduce your voltage setting. To find the optimum voltage, use a test piece and reduce your voltage in increments of half a volt until the problem goes away.

The big advantage of gasless mig welding is you don’t have to use industrial shielding gas, saving you lots of money on cylinder rental/leases.

Shielding gases are expensive and if you aren’t doing alot of mig welding, a cylinder sitting in your garage or shop is costly on a monthly or yearly basis.

For more information and video about gasless mig welding, please read this article from one of our valued suppliers MillerWelds.

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