What is Spatter In Welding? And why it sucks

By Bill Byers / December 17, 2018
What Is Spatter In Welding Title Image

What is Spatter in Welding?

Spatter is expressive, looks impressive, the sparks and fireworks flashing and dancing everywhere that is so typically seen. It is part and parcel of the seduction and drama of MIG welding. 

Welding Producing Spatter

Welding Producing Spatter

​I want to weld like that I hear you shout.

However too much spatter in welding is not a good thing.

What? Why?

I hear you ask?

Because the direct result of spatter is a lot of time spent cleaning up after you have welded. And that sucks big.

Spatter is the inevitable by product of the act of MIG welding. It is a fact of welding.

However the professional welder will have perfected the art of keeping spatter to the absolute minimum - you can find out how too.

And I'll explain shortly why they do.

​Welding Spatter Up Close

​Your MIG welder​ uses electricity to melt the base metal - your welding project - so that it melts and fuses with the metal from your electrode - your welding wire - into the weld pool - the point where your base metal and the metal from your welding meet, meld and fuse together.

Welding Process

Welding Process

​To achieve that, high temperatures must be achieved and along with high temperatures, the electrical energy generates magnetic forces.

Welding spatter is tiny pieces of molten metal and other weld contaminants jump away from the weld pool in the form of small hot globules.

These globules then impact and stick onto cold surfaces. Onto the base metal your welding, your welding table and any surrounding it can get to in your workshop or garage.

Indeed anywhere they can reach and stick.

Those hard to get off bits of metal is your welding spatter.

Another way of looking at spatter is that it is the end of the welding wire that didn't fuse into the weld pool.

​Why Bother to Reduce MIG Weld Spatter?

And that is a perfectly reasonable question. After all it looks so great and proves your really welding.  Doesn't it?

It is worth spending some time working out what is causing spatter if you're having spatter to excess when you are welding because;

1. Spatter will stick to your weld project and to your MIG gun, defacing them.

2. Spatter will do its best to stick to you. It will go onto your head, the back of your neck, your hair, arms and into places you didn't even think you had places.

3. And when spatter gets there those hot pretty little molten globes will burn off your hair, skin and set fire to any of your clothing that isn't fire resistant. It is a reason why the better makes of weld clothing have no pockets on the outside. Spatter just loves pockets.

4. Spatter can ruin the finish of your weld project piece by pitting and scratching up the surface

5. Spatter will have you spending precious time perfecting your grinding and chiseling skills getting the spatter off.

6. Spatter will stick to your MIG gun nozzle filling it up with spatter.

Spatter Build up On Nozzle And Contact Tip

Spatter Build up On Nozzle And Contact Tip

​Which can cause gas flow issues, meaning your shielding can't work to protect your weld properly. Spatter sticking to your MIG nozzle can also cause wire feed issues. Both these situations can lead to porous and failed welds.

7. Spatter will stick to your contact tip, causing wire feed issues and wearing out your contact tip faster.

8. All those pieces of spatter are molten bits of metal. Metal from your welding wire that is supposed to be your filler metal and that metal is not going into your weld where is should be. Those dollars you spent on good welding wire is spread around your work area and shop causing you grief cleaning it up.

Summarizing, you bother - take the time to reduce spatter because it burns, causes excessive clean up and ultimately all those pretty sprays of sparks could mean you have a poor weld. The last thing you need.

​What Causes Spatter when MIG Welding

​Weld spatter has a few causes and it is best to go through striking each one off the list till you find the causes you have in your weld area.

​1. Is Your Weld Pool Too Hot or Too Cold?

​The ideal conditions leading to weld spatter is when you have the wrong settings on of amperage for the metal you are welding and the welding wire you are using.

When the Amps are too low the weld pool is too cold.

This is the main cause of weld spatter.

Instead of being fluid, warm and welcoming to the melting welding wire,

Low Carbon Steel Welding

Low Carbon Steel Welding

the surface tension causes the welding wire to bounce of the weld pool, scattering small pieces of molten metal - spatter.

At the opposite end, when the amperage is set too high. The welding wire literally pops and the weld bead that should be flowing into your weld pool breaks off and scatters

- producing spatter.

​2. The Shielding Gas You use

​The type of shielding gas you are using for your MIG welding. 100% Carbon Dioxide is a popular choice when MIG welding because it is a cheaper gas to buy and is used where greater penetration of the weld into the base metal is needed.

However Carbon Dioxide is infamous for producing more MIG welding spatter.

As can C25 gas mixture - 75% Argon and 25% Carbon Dioxide produces more spatter than a mixture of 80% or greater Argon gas.

Argon Tank Welding

Argon Tank Used for MIG Welding

​C25 is nowhere near as bad as pure Carbon Dioxide. But as you up the level of Argon gas in your shielding gas mix the costs of your shielding gas goes up.

It is a trade off.

​3. Wire Feed too High or too Low

Mild Steel Solid MIG Wire

Good Quality Mild Steel Solid MIG Wire

​Should your MIG welder not feed your welding wire at a consistent speed then the amperage in the welding wire will vary. I've already covered how too high or too low Amps affects the weld pool causing spatter. Let us have a look at other wire issues that can lead to spatter.

​4. Poorly Wound Spools of Welding Wire

​Will give wire feeding problems as will poor welding wire with an inconsistent chemical make up.

Changes in the levels of metals throughout the spool of welding wire or even small variation in the wire diameter will cause spatter.

Because it varies the amperage depending on whether the wire is slightly larger or smaller in diameter.

As will variety in the levels of copper coating on the welding wire.

5. Welding Wire Stickout


Welding Wire Stickout

Welding Wire Stickout

​Incorrect wire stickout from the nozzle of your MIG welding wire will cause spatter. As will the distance you maintain from your weld pool.

As bits of your welding wire can literally bounce off a weld pool as incorrect distances causes poor arcing.

​6. Connections, Connections

A poor quality ground clamp or poor connections to your ground clamp can cause an unstable arc.

As can the wrong polarity, it is worth double checking. Particularly if you have just swapped from flux core welding to MIG welding. Check, have you set your polarity terminals right?

Example of MIG Polarity Terminals

Example of MIG Polarity Terminals

​​7. Welding Wire Storage

It pays to make an effort to store your welding wire correctly.

And that doesn't mean in your MIG welder. If you have a half used spool take it out and put in a well sealed plastic bag to keep any rusting or moisture on your wire to a minimum. Moisture and rust causes spatter.

And on the subject of moisture.

​8. Where you Weld

Welding in a high humid atmosphere can produce more weld spatter. If you live in a humid part of the country at the wrong time of the year you may need to accept a bit more spatter.

Welding outside with no protection. Wind blowing away your shielding gas means poor coverage for your weld pool and spatter.

​9. Weld Contaminants

​'Dirty' steel, rust, paint, oil, mill scale - are all contaminants that the welding arc has to contend with when forming your weld.

Dirty Steel and Spatter

Dirty Steel and Spatter

​As the Arc strives to burn through them it uses up the voltage/Amps available to your MIG welder to weld. Those contaminants contribute to a cold weld pool - I covered earlier how a cold weld pool causes spatter.

​10. The Method your Welder Uses to Melt the Welding Wire

​As a home welder with a MIG welder using 120 volt.

Or if you can put it in, 230 volt power in your home, there are a few methods your MIG welder will use to melt your welding wire and transfer it to the weld pool.

Your welding wire electrode will transfer to your weld pool based on the power available and the shielding gas you use.

1. In short arc or short circuit welding, the welding wire transfers to the weld pool when contact with the weld pool is made.

Short Circuit Wire Transfer

Short Circuit Wire Transfer

2. With globular the metal from the welding wire transfers in droplets of molten metal that drop into the weld pool.

Globular Wire Transfer

Globular Wire Transfer

​You'll see from the picture that the shape of the metal from the welding wire forms balls or spheres and drops into the weld pool

Both these methods produce more welding spatter.

3. A third method is Spray transfer where very small drops of metal (smaller than globular) drop into the weld pool.

Spray Wire Transfer

Spray Wire Transfer

​The smaller spray of metal keeps the arc more stable and so reduces spatter.

​YouTube Video on Welding Wire Transfer Methods

This 1 minute 27 second YouTube video is fantastic as it shows in slow motion and up close the different methods your welder could use as it works to transfer the metal from your MIG welder into your weld.

Metal Transfer During Arc Welding

From the Canadian Centre for Welding and Joining, University of Alberta.

Video Credit: Bhadeshia123

You may or may not be able to affect the method your MIG welder uses.

 I explain more in the next document in this series, 'How to Stop Welding Spatter and Tactics to Reduce It'. Follow the link to go over to read it. ​

​Last Words

​To answer the question what is spatter in welding, in summary spatter are droplets of molten metal (or non metal contaminants) that spread around your welding area.

Don't ruin your beautiful welding experience with the frustration of tons of clean up due to spatter spray everywhere because that sucks.

On everything including on you, your work, the floor and your MIG gun.

Combat spatter and I tell you how in the next document. Just follow the link. ​

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