What Causes Weld Spatter? And Tips On How To Reduce It

Published on

For serious welders, like those of you reading this article, spatter might as well be a four-letter word. There is nothing good about it. So, it is fair to wonder:

What is spatter, how is it caused, and how can it be prevented?

What is Spatter?

For those who may not know, spatter consists of molten balls of metal that fly from the weld pool and attach themselves to anything nearby. Usually, that just happens to be you, the metal you are welding, or your tools. 

Since these balls are melted and very hot, they stick firmly to whatever they contact. If that is your workpiece, it makes a mess that you have to clean. In short, spatter makes your welds look sloppy.

But if it lands on you, that means your flesh is about to let you know just how hot these pesky spheres are. They can burn through clothing and scorch your skin. Ouch!

Plus, small blobs of metal that get stuck to your tools can clog gas ports or create various problems with your gear.

Since you ejected some metal from the weld as spatter, in severe cases the integrity of the weld might be questioned. As you can see, spatter is a real problem, for many reasons.

So, spatter may not be a four-letter word but it does have the power to induce a steady stream of them from a welder.

What Causes Weld Spatter and How Do I Prevent It?

In general, spatter is caused when the weld pool is disrupted in a way that causes the molten metal to spit or spray out of the weld.  

That means spatter can be caused by a number of things. The most common are:

  1. Material Composition
  2. Contaminated/Dirty Materials
  3. Welding Technique
  4. Welder Settings
  5. Equipment Issues

Metal and Filler Composition

Some metal is better than others. Cheaper metal often contains a lot of “filler” to keep the cost down. But the materials used as fillers in the cheaper alloys often make the metal unweldable. If you try, spatter will be inevitable.

The same is true for your filler materials. The cheaper rods and wire also can include materials that make the filler material prone to spatter. 

How to Prevent Material Composition Related Spatter

So, if a low-quality metal and filler can create spatter, do quality materials reduce spatter? As it turns out, yes.

It should go without saying, you need to know and understand the metal you are welding. If it is quality material, suitable for welding, spatter will be less.

This is also true for your filler. Do your research and understand what you are buying. You should get the best filler wire and rods you can find. The quality of your weld depends on it and this will also help to reduce spatter.

Dirt and Contamination

Have you ever seen what happens if you add water to hot oil? It causes the oil to spit and splatter everywhere.

Think of dirt and contamination in the same way as water getting into hot oil. It will cause the molten metal to spit and splatter, causing spatter that you have to clean.

Also, you need to consider oil and other protective coatings or material applied to the metal by the manufacturer as contamination. Sure you can weld through most of these surface treatments, but you will be cleaning up more spatter if you do.

Cleanliness is needed with your filler material, too. It is easy to ignore the dirt and oil that can get on welding wire or rods stored in a shop. Plus, they can rust over time. But dirty, rust, or contaminated filler materials can cause spatter, too.

How to Prevent Dirt and Contamination Related Issues

If dirt and contamination, cause spatter, eliminate it like the Terminator searching for Sarah Conner. Only you don’t have to rip pages out of the phonebook first. 

All kidding aside, dirt and contamination is the enemy and you need to clean meticulously as part of your weld prep.

Dirt, oil, and rust should be removed on ¾ of an inch on each side of the weld. Grind, wire brush, or use a flap wheel if necessary. Bright metal is usually best.

Plus, remember your filler material needs to be clean, too. Be sure to store it in your shop undercover and in a cool, dry place. You do not want dirt, dust, oil, etc. to settle on it, nor do you want it to rust.

Welder Settings

It is easy to use rules of thumb for welder settings, but they can become a crutch. Every weld has optimal settings and your equipment should be adjusted for the specific weld you are doing.

If the “heat” and penetration are not right, you risk disrupting the welding pool and increasing spatter.

With a MIG welder, you must also get the wire feed correct. Too fast and you send solid metal wire into the pool, which causes a disturbance more than adequate to create spatter. Too slow, and you vaporize the wire before it gets to the weld. Again, more spatter.

Also, using the wrong polarity can cause a lot of spatter. Forgetting to flip it back for solid wire after using flux-cored happens to everyone once in a while.

Another “setting” connected to how to reduce spatter with your MIG welder – the gas.

If the flow rate, the gas blanket, or the type of gas are wrong, it can impact how much spatter results.

How to Prevent Setting Related Problems

To address how to reduce spatter when mig welding or using a stick, discussing MIG and stick welders separately is helpful.

MIG Welder Settings

Once in a while, you start a bead and see as much metal fly off as lays down in the weld. Check your polarity. You probably forgot to flip from flux-cored wire to solid.  

Also, the current and/or voltage must be correct to achieve good penetration and the proper heat. These settings work hand in hand with a correct wire speed.

If you feed wire too slowly, the wire melts too far from the metal and it liquefies in the air instead of laying down in the bead. The result is spraying the molten filler outside of the weld, creating spatter. If this happens too close to your gun tip, you can even clog it.

Feed the wire too fast, and you send solid wire “poking” into the molten pool. This disrupts the melted metal and one of the results is spatter.

The stick out must also be set correctly. A rule of thumb often stated is ⅜ inch. But it can vary based on the geometry of the weld. But too much stick out will result in more spatter, as well as a number of other problems with the weld.

Another thing to check, your gas. First, you need the right gas for the weld to be made. Use the wrong gas, and you will get poor weld results, with more spatter.

Then, you must also make sure you have a good gas blanket, evenly distributed while welding. Get the flow rate wrong or apply a turbulent blanket of gas, and air will contaminate and affect your weld. One of the results is more spatter.

Stick Welder Settings

Your speed is linked to the current and/or voltage settings. Too hot, and you must move fast. If you recall, one of the causes of spatter with a stick is moving too quickly.

On the flip side, too cold and your welding is rough. It fluctuates between welding and sticking, which causes spatter and an unsightly weld. 

Special Note on Welder Settings

To dial your settings in, it might take some experimentation. Practice on scrap pieces of metal and slowly dial in the settings. If you make big changes, you risk jumping over the sweet spot.

Yes, this takes some time, but it also improves your welds, and reduces the amount of spatter.

Welding Technique

So you did meticulous prep, the metal is shiny clean, and you used the best, clean filler material you can find. Plus, you have your equipment settings dialed to the perfect settings for the weld you are about to make.

But that is not enough. Your technique can also create excess spatter. For example, the angle of the MIG gun can create spatter. Drift over a 15° angle, and the amount of spatter starts to increase. 

The same is true if you are stick welding; your technique matters. For instance, let your arc length get too long and the amount of spatter increases. 

Also, the speed at which you move with both types of welders can increase the amount of spatter. If you too move too fast or slow, it creates more spatter.

The “proper” technique has become the correct way for a reason. It produces the strongest, cleanest looking welds based on years of experience.

How to Prevent Technique Related Issues

Welding is an art in that it relies on the expertise of the user’s technique to achieve a good looking, quality weld. Technique is also key to keeping the weld spatter to a minimum.

Mig Welder

You need to get the direction you move while welding right. If you need high, consistent heat, pulling your weld is better. When you need heat distribution, pushing is more appropriate. This varies depending on the material being welding, but get it wrong, and you get more spatter.

The angle of the gun must not exceed 15°. Get steeper, you guessed it, more MIG welding spatter.

Also, move at a proper speed. Moving too fast or too slow impacts the quality of the bead. But in many cases, it will also create more spatter.

Stick Welder

Same as with MIG welding, you cannot move too fast. It will create more spatter. One of the reasons for having to move too fast is the current and/or voltage may be set too high.

Another thing to make sure you get right, the arc length. In general, keep the arc length equal to the metallic core of the electrode you are using for the stick weld.

Equipment Issues

Your equipment settings are not the only thing you need to worry about. You need to worry about keeping the gear in tip-top shape. 

Have you ever asked, why does my MIG welder spatter? Part of the answer may lie with your equipment condition. If you have any issue impeding its performance, it can cause spatter.

An erratic wire feed, a bad ground with your clamp, an insufficient layer of shielding gas, or a worn or incorrectly sized contact tip can all cause your MIG welder to create excess spatter.

Any issue with your equipment that causes an inconsistent current, poor filler feed, improper shielding, etc. all contribute to spatter.

How to Prevent Equipment Related Issues

To produce quality welds, which includes reduced spatter, your equipment must be running as designed. 

One of the more often overlooked details – the ground clamp. If it is not clean or it is unable to make good contact with the piece, the current can fluctuate as you weld. This will create more spatter with both a stick and MIG welder.

MIG Welder

To reduce MIG welding spatter, your wire must be fed continuously at the proper tension, with no snagging or other restrictions. A smooth, consistent wire feed must be provided to achieve a clean weld.

The shielding gas must flow freely at the right rate. Make sure your hoses, regulator, gas ports, etc. are all connected and functioning properly. It is common for hoses to become unconnected or crimped and ports can get clogged.  

The contact tip must also be in good condition and properly sized. These can wear out, but a more common problem is using the wrong size. It can be hard to read the markings and it is easy to install the wrong size contact tip.

How to Clean Spatter

After taking all the precautions you can, you may still get some spatter at times.

When spatter occurs, you usually need to clean it to make the weld look its best. 

The bad news is the job is tedious. But the good news is you do have some options. Such as:

  • Grinding,
  • Chipping with a Spatter Hammer, and
  • Using anti-spatter sprays, gels, or tape.

Grinding

One method of cleaning spatter is breaking out the tried and true angle grinder. It works but takes time and effort.

However, if you are grinding as part of the finishing operation, hitting the spatter at the same time makes sense.

Spatter Chisel or Hammer

For those times when you get a small amount of spatter, a chipping hammer works well.

It is designed and manufactured in such a manner that it removes the offending spatter quickly without damaging the base metal, leaving you with a cleaner looking weld.

Sprays, Gels, and Tapes

Another strategy you can employ, don’t let the pesky little blobs stick in the first place. You can apply sprays and gels which are designed to keep spatter from adhering. 

Some welders also find tape works well, too, to mask certain areas. But use aluminum tape, it holds up to the heat of the spatter and does not melt like plastic tapes.

About Jeff Grill

Jeff Grill hails from Long Island, a 118 mile stretch of land that starts just off the coast of Manhattan and stretches deep into the Atlantic ocean. He has always been interested in welding from an early age and has the cuts and bruises to prove it as he set out to work with a variety of metals.

Leave a Comment