How To Properly Set Your MIG Welding Polarity Settings [Updated]


Have you ever wondered how to properly set your MIG welding polarity settings? One of the most important things to keep in mind when welding is that every little setting has a big difference. On the one hand, this can be a great way to unleash your creativity. The more settings, the more control you have, which in turn allows you to do that much more when it comes to tweaking every little welding detail to your heart’s content. On the other hand, however, there is no denying that more settings can be overwhelming, especially when it comes to something like polarity.

So, how can you maximize your welding polarity settings in such a way as to make them as creative and efficient as possible?

Why it Matters

First, it is worth asking why all of this matters in the first place. After all, you already have so many other things of which to keep track when it comes to welding things. You would be forgiven for throwing up your arms, saying it’s all too much, and just saying you’ll use “whatever polarity setting” you have.

But doing so will produce kneading, beading, and other poor results. The wrong polarity can produce long slabs of unsightly metal that doesn’t melt properly, looking less like a sleek clean weld and more like a blobby globule of metallic slag.


That isn’t even getting into the way in which little dots of metal residue can form at various points all around the welding point. All of this can stem from using the wrong type of flux core in conjunction with the wrong type of polarity.

The point is that you need to make sure that you are using the right kind of polarity setting.

Related reading: The Problem with Weld Spatter – and How to Stop It

How to Avoid This Issue

If you want to avoid your welds looking like a splattered mess, the first thing you need to do is make sure that you are using the right type of polarity, which begs the question – what is polarity in the first place? As anyone who works with anything electrical knows, polarity refers to positive and negative poles at either end of the item in question. The positive and negative ends form a circuit.

Polarity is a big deal in welding because it has a direct impact on the quality and strength of the weld – we’ve already seen above how things can go wrong when your polarity goes awry.

Straight Versus Reverse Polarity

In welding, you need to choose between straight and reverse welding, which are the common terms for referring to the negative and positive electrodes, respectively. The different polarities have different impacts on the nature and quality of the weld.

Positive-electrode polarity typically results in deeper penetration, making it easier to weld deeper and stronger. By contrast, negative-electrode polarity melts things off faster, making it that much easier to get rid of excess metal in a quick and timely fashion.

As you might imagine, these can have a tremendous impact on the nature and quality of your welding. Let’s say that you are welding something that requires a good deal of penetration because of the thickness of the metal. After consulting the points above, you’ll be able to tell that positive polarity is probably the best way to go. By contrast, if you need to dissipate metal fast so as to keep it from building up and causing the kind of fast, out of control splattering as described previously, you’ll likely want to go with a negative polarity.

There is, thus, no right or wrong answer to the question of which polarity is right for you. Rather, it is the question of different welding approaches and solutions thereto.

AC Versus DC

These are not the only elements where you might get “the wires crossed” when it comes to welding and polarity. There is also the question of Alternating and Direct Current, or AC and DC. The former alternates the flow of the electrical current in conveying it from Point A to Point B, while the latter only creates a flow in one direction. As a result, DC welding machines have constant polarity. By contrast, AC machines have changing polarities, with the flow alternating at 120 times per second (assuming a current of 60 hertz).

When to use which once again comes down to the situation in which you find yourself welding-wise. When you are working with shielded metal arcs, DC is often used for a variety of reasons, not the least of which being that its direct currents create more stable arcs. In addition, it suffers from less spatter and more outages. That said, beginners sometimes opt for AC because of the low cost.

Related reading: What Does DCEN Stand for in Welding?

Additional Polarity Insights

Not only do you need to choose between the different polarities and AC and DC, but you also need to consider the flux core wire. This is an essential part of the process which needs to remain stable, less you once again find yourself in Splatter City.

To avoid issues such as splattering, you will want to make sure that you change your MIG welder polarity settings whenever the time comes to change from a solid to a flux core wire.

That said, there is still one more distinction to draw between solid and gasless MIG welding wires. The former is typically used when shielding gas is being used. This shielding gas can be mixed in different ratios (for example 25% CO2 and 25% argon) when using a solid wire.

All of this means that it is incredibly important to consider the nature of your welding polarity in the context of everything else – the metal you are welding, the shielding gas you are using, and what your intention is with the project.

Related reading: How to Use a MIG Welder Without Gas | Is Gasless MIG Welding any Good?

As you can tell, there are many different aspects of welding polarity, any number of which can cross your wires and leave you with splattering or worse. Thankfully, if you follow the basic guide above and make sure that you have your polarity settings right, you can weld cleanly and with increased confidence, thus, allowing you to produce a superior product.

Related reading: What Types of Gas Welding Are Commonly Used? | Are they popular?

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David Harper

David is the Co-Founder and Senior Editor at David's an experienced fitter and tuner/welder who's passionate about helping others develop in life through new skills and opportunities.

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