The Problem with Weld Spatter – and How to Stop It


Weld-Spatter–How-to-fix-It

When we close our eyes and picture someone welding, the first thing that comes to mind is the bright light of the arc and the dramatic sparks shooting out every direction. The truth is that those sparks are a problem. The sparks are called “weld spatter,” and they make a mess by sticking to everything they touch.

How can you reduce weld spatter?   You can minimize spatter by configuring your welder correctly, using proper technique, and coating the weld area with an anti-spatter spray can all help.

Stopping weld spatter starts before you ever crack an arc. The key to stopping spatter is understanding how to set up your weld and position the gun for the weld.

What is Weld Spatter?

Weld spatter is the spray of little drops of metal blow out of the weld arc as you work. Spatter occurs most often when MIG welding, but can also be a problem for stick welders. The American Welding Society (AWS) includes weld spatter on their list of welding defects.  While it’s not as bad as some other welding defects, spatter is still an issue. Flying metal drops cause several problems.

  • Spatter causes burns if it lands on your skin. Even if you don’t care about anything else, you should try to avoid getting hurt.
  • Spatter can start fires if you aren’t careful about your work area. Fighting fires probably isn’t on your to-do list when you head to the shop to weld.
  • The drops stick to the workpiece. This is a cosmetic defect on anything you weld. It’s worse on moving parts because it can cause extra friction or wear. Worst of all is spatter on an item that will be handled frequently – those little beads can injure people when the item is used.
  • Cleaning spatter wastes time that you could spend welding (or even things that aren’t welding).
  • Unless your clothes are fireproof, spatter will burn holes in your clothing. Eventually, the clothes will be wrecked by spatter. You probably don’t care how your welding clothes look, but replacing them costs money.

Spatter or Splatter?

The word “spatter” isn’t widespread in everyday use. We typically say that things SPLatter, not SPatter. The two words are closely related and are interchangeable in everyday use. We are only talking about spatter here, without the “L.” That’s because the formal term for the defect, as defined by the AWS, is spatter. Since that’s the technical term, we’ll stick with spatter here.

How Bad is Spatter?

Some weld defects are a problem, no matter what. A cracked weld won’t hold – eventually, the two pieces you joined together will break apart again. Spatter isn’t that way. Sometimes it’s not a big deal. For example, I recently welded a structural member on a piece of farm equipment. A little spatter on that piece is no big deal because no one will ever touch or even see the weld.

Spatter on a tool handle or handrail is a deal breaker – it will cut your hands up. Likewise, spatter on an engine part that moves is a real problem because it will damage the other parts around it. If you get lots of spatter on something for interior use, you’ll have to spend time cleaning it up.

Spatter on a workbench is also a problem. A couple of drops might not seem like a big deal, but eventually, spatter can build up to the point that your table is no longer flat. The worst-case scenario is a table that’s so lumpy with spatter that you can’t lay out projects correctly because of the lumps and bumps. You can take time to clean that spatter, but it’s easier to stop spatter in the first place.

Related reading: Here, you can find an article from our website about the topic: 11 Common Welding Defects and How to Prevent Them

What Causes Excessive Spatter?

Spatter starts with the weld puddle. The weld puddle is the little pool of liquid metal where the arc and the filler meet the workpiece. A good weld puddle is the secret to a clean, spatter-free weld. A bad weld puddle will make a mess for you.

We tend to think of metal as solid and unyielding. Metal is that way most of the time – that’s what makes it a useful material for structural work. The weld puddle isn’t solid, though. You must think of the puddle as a liquid to get it to behave.

Spatter comes about when the puddle is disturbed by filler metal, disruption to the weld bead, and even the arc itself. Whenever something hits or jars liquid, it splashes. Splashes from your weld puddle are what make weld spatter (Check out the video below). To minimize spatter, protect the weld puddle from disturbance. Using the correct voltage, amperage, wire, and welding technique will help you cut down on the splashes.

Metal transfer during arc welding >> Check out the video below

Machine Settings

The first step in reducing spatter is to get your welder set up correctly. Welding machines have a wide array of settings; each needs to be correct to get the best results. Often the settings are printed on the welder itself. If they aren’t, refer to the manual. (You do have the manual, don’t you? If not, they are available online.)

The first settings to check are the current settings: amperage and voltage. You can think of the weld gun as a hose, and the arc is the water coming out of the hose. Amps tell you how big the hose is – higher amperage is like using a bigger hose. Volts tell you the pressure – how fast the water sprays out of the hose. To minimize splashing coming from a hose, you need to adjust the water settings to get a smooth flow.

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Perfect Welds

Welder settings work the same way. You need to adjust the amperage and voltage to get the smoothest spray of metal coming off the filler rod to minimize splashing the weld puddle. Here are the settings you need to adjust to reduce spatter.

Amperage

Higher amperage will make the weld puddle splash and spatter. Just like using a fire hose causes more splashing than a garden hose, high amperage causes spatter. Use the lowest recommended amperage for the thickness of metal you are welding. You won’t be able to move as fast, but you’ll save time when you don’t have to grind off spatter from all over the place.

Amperage drives penetration. Higher amps mean deeper penetration of the weld, but it also makes the puddle more turbulent. If you are going for the deepest penetration, you may have to live with some spatter. If you can allow less penetration, lower amperage produces a cleaner weld. Don’t reduce the amperage below the recommended level, though. That leads to weld failure.

Related reading: How Many Amps Do I Really Need for a MIG Welder?

Voltage

Spatter increases when the voltage is too low. Low voltage causes the filler wire to drip into the puddle in bigger chunks. Big stuff hitting liquid means splashing – that’s how you get spatter. If you are trying to get a weld bead to penetrate thick material, turn the amperage down and the voltage up. This combination gives you a smooth weld bead and attractive results – without lots of spit and spatter.

Don’t just turn the voltage up all the way, though. Too much voltage makes it hard to control the arc and reduces penetration. It also produces a weld bead that stands tall and is marked by pits and lumps. If you are getting too much spatter at the recommended voltage, increase it in small increments. Bump the voltage, weld a little, and check your bead. Back off the volts when the bead starts to get ugly.

Arc Blow

Arc blow is a phenomenon that isn’t fully understood. It occurs when the weld puddle becomes magnetized.  When a strong enough magnetic field surrounds the puddle, the arc can wander away from the tip of the electrode. The arc can bend, wave, and deflect from the line you are trying to weld. All this motion disrupts the weld puddle and causes spatter. If you are having problems with arc blow, consider the following:

  • Run AC power. Since the polarity of AC welds changes several times per second, the arc doesn’t have time to be deflected. DC usually gives better welds, but sometimes AC is the best choice.
  • Shorten the length of your arc. A short arc can’t wander as far. It also requires less current, which reduces the magnetic field around the arc. Get your gun closer to the weld puddle.
  • Coil the ground cable around the piece you are welding. This can disrupt the magnetic field of your workpiece. The coils work like an electromagnet and help control the existing magnetic field on the workpiece.
  • Move the ground clamp. Some people swear that welding closer to the ground clamp reduces arc blow; others swear by getting the clamp as far away as possible. Try both and see what works.
  • Change your electrode angle. Sometimes changing the arc angle helps control arc blow. A flatter arc gives the weld spray a little momentum that the weak magnetic field can’t overcome.

Related reading: What’s The Difference Between AC And DC Welding >> AC vs. DC

MIG-Only Issues

Problems with electric current setup can happen with any arc welding process. MIG welders have a few unique characteristics that can make spatter worse. Here are a couple of MIG-only causes of spatter that may cause problems.

Wire Feed Speed

MIG welders use a continuous wire as a combined electrode/filler metal. This setup lets you lay down bead at a high rate, but it can also contribute to spatter problems. The most common wire problem that causes spatter is a wire feed rate that’s too fast for the project. When the wire is feeding too fast, pieces of wire break off and splash in the puddle. Instant spatter!

Make sure you are using the recommended wire feed speed for the amperage you are using. If you are still getting too much spatter, reduce the feed speed to reduce spatter. You won’t be able to move quite as fast when you weld, but you’ll save time when you don’t have to scrape spatter away.

Don’t feed too slowly, though. Feeding the wire too slowly will also cause spatter. Slow feed turns the steady spray of filler into a drip, drip, drip. Those drips turn into splashes.

Wire Length

If you start welding with too much wire sticking out of the gun, you’ll get spatter. It is just like having the wire speed set too fast – wire breaks off and splashes the puddle. Keep pliers handy to trim the wire when it sticks out too far before you start the weld and keep the gun tip around half an inch from the weld puddle while you work.

Gas Flow Speed

A little shielding gas is good, so more must be better, right? Wrong! If you set the flow too fast, the shielding around the weld becomes turbulent. Like high winds over water, the gas flow can cause waves and splashing, leading to spatter. It can also cause other problems if eddies in the gas flow let air get to the weld puddle. Make sure the gas flow is correct.

Gas Type

Carbon dioxide (CO2) is the most common shielding gas for MIG welding, mostly because of price. It’s also the worst gas for causing spatter. Argon is more expensive but reduces spatter. CO2/argon blends offer a tradeoff between spatter and price. You’ll have to decide how much your time is worth – do you want to spend money on argon, or save cash and spend time chipping spatter?

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

Wire Type and Age

Cheap filler wire is more prone to spatter than costly wire. It’s the same tradeoff you get with shielding gasses – do you want to spend the money on good wire, or the time on cleaning up spatter? Wire age also matters. An old wire can oxidize or absorb water vapor from the air, causing spatter. If spatter is a big problem for you, make sure to use your wire up regularly or store it in a way that prevents damage.

Clean the Weld Gun

Spatter gets on the tip of your weld gun as well as the workpiece. When the tip of the gun is gunked up, the gas flow and arc can be disrupted – causing more spatter. If you have been having problems with spatter, make sure to scrape the tip of your gun clean. Needle nose pliers work well for that because you can grab the spatter and pull it off in chunks.

Play with the Settings

The manufacturer’s recommendations are the best place to start when trying to reduce spatter, but they aren’t the last word. Welding is as much an art as a science – feel free to adjust the settings to reduce spatter. This is particularly important if you do a lot of work that is similar. You can move away from the recommendations a little at a time to see what happens. Don’t be afraid to experiment a little to get the best results.

Base Metal

The condition of your base metal also makes a difference in controlling weld spatter. Clean, shiny metal welds best. Rust, mill scale, grease, oil, and paint can all cause weld spatter. Anything other than fresh metal along the weld joint causes popping and snapping, leading to weld spatter. Make sure you follow these tips when you prepare a weld joint:

  • Wash off dirt and mud. Some welders never encounter this, but off-road and agricultural equipment is likely to come with a layer of mud or dirt. Pressure wash the weld location to get rid of the worst dirt and mud.
  • Grind away contamination. Use a sander or grinder to remove rust and mill scale. Welds work best when the metal is shiny.
  • Wipe away grease, oil, and paint. Use a rag with acetone or paint thinner to get every last bit of organic chemicals off the weld joint. Solvents will remove material that has become trapped in pores and scratches in the metal as well as the surface layer.

Eliminating surface contamination will eliminate a lot of weld spatter. It also keeps the air in your shop cleaner since you aren’t burning away the gunk. Finally, cleaning up the base metal reduces other defects as well. You’ll get better penetration and a cleaner bead if you weld clean metal.

Poor Technique

Another cause of weld spatter is poor technique. The way you set up the weld and handle the gun can cause spatter. Poor technique is one of the easiest spatter causes to fix. All you need to do is pay attention to your technique. You’ll get reminders when you get sloppy, too – the spatter will come back and let you know you’re doing it wrong.

Flat Gun Angle

The ideal gun angle for MIG welding is no more than fifteen degrees off vertical. That isn’t very much. Picture a clock. If the hands are pointing to twelve and one, the angle is thirty degrees. Fifteen degrees is only about two minutes past twelve.  (Or two minutes before twelve, if you are left-handed.)

Beginning MIG welders often hold the gun too far from this angle. It’s tough to see the weld puddle with the gun held almost vertical, but this is an essential skill. Make sure you have the gun at the right angle before you crack an arc.

It can also be helpful to rehearse the weld before you pull the trigger. Hold the gun and run your hand through the length of the weld to make sure you can keep the gun upright the entire time. If you can’t, change your body position or setup to keep the gun at the correct angle.

Related reading: Do You Need a Spool Gun to Weld Aluminum?

Arc Too Long

It’s common for new welders to hold the gun too far from the puddle so they can see the puddle better. This causes a long arc. When the welding arc is too long, the filler metal will drip and splash rather than coming out in an even spray. The ideal arc length is one-half to three-fourths of an inch.

Use Your Ears

When it’s done right, MIG welding should produce an even, steady sizzling sound. If you hear pops or cracks, you are getting weld spatter. Once you know what the arc should sound like, you can stop and adjust things immediately before you get spatter everywhere. This is a skill that will only come with experience, though.

Dealing with Spatter

Spatter is a fact of life for welders. Even after you have adjusted your machine settings to reduce spatter, it still happens. There are a variety of methods used to clean up spatter. Some cost money, while others just require you to spend time. When it comes to cleaning spatter, you have to decide if you want to save time or money. So what can you do to get rid of weld spatter?

Anti-Spatter Sprays

There are a variety of sprays available that promise to eliminate spatter. These sprays all contain proprietary ingredients, but they have the effect of stopping spatter drops from sticking. If the spatter lands on the area you have sprayed, it sticks to the coating and not the base metal. Once you are done welding, the spatter droplets can be wiped away with a cloth instead of requiring a grinder.

Be careful with these sprays – don’t get them in the place you want to weld! The chemistry of the spray stops weld filler from sticking to the base metal. If you spray along the seam, your weld bead won’t stick! This defeats the purpose of welding – a bad bead is a much, much worse defect than spatter.

Aluminum Welding Tape

Although it’s more commonly used to purge the back of weld seams, aluminum welding tape can help fight spatter. Placing the tape alongside the seam will give the spatter something other than base metal to stick to. Once you are done, just peel off the tape, and the spatter is gone. Make sure to use aluminum tape – fiberglass or other materials can burn when the spatter lands on them.

aluminum-welding-tape

Welding tape lets you block off spatter close to the seam and doesn’t impact the weld bead at all. The biggest drawback is the price – aluminum tape isn’t cheap. As with other expensive spatter control methods, you’ll have to decide whether the time savings are worth the price.

Cold Chisels, Angle Grinders, and Sanders

These are the time-honored ways to deal with spatter. Welders have used chisels and grinders to remove spatter for decades because they work. To use a cold chisel, place the chisel’s edge against the beads of spatter and tap with a hammer. This can leave small nicks and gouges on the base metal.

 The best angle grinder set up to remove spatter is a flap wheel. It will knock off the spatter without affecting the base metal too much. If you want to leave the surface shiny, follow the grinder or chisel with a belt sander. The sander will give you a smooth surface that looks great. Sanding is only needed for cosmetic purposes, though. If looks aren’t terribly important, grinding is usually enough.

Tips To Avoiding Excess Weld Spatter >> Check out the video below

Practice Makes Perfect

There is certainly a lot of science to welding – electrical currents, metallurgy, and engineering specs are vital to getting clean, strong welds. Welding is also an art. An arc that produces a clean, strong bead has a sound and a feel. Puddle control and arc stability come from the right touch with the weld gun. Even configuring the welder and tweaking settings require experience.

Producing good welds comes with time behind the arc. The final piece of spatter reduction comes with practice. The more you weld, the more proficient you’ll become, and the less spatter you’ll get. You can’t eliminate spatter completely if you MIG weld, but you can reduce it considerably.

The essential part of acquiring welding skills is to try different things. Weld different thicknesses of metal or different alloys. Play with welder settings to get less spatter. Try different gun angles and holds. Push and pull the bead to see what happens. The more things you try, the better you’ll get at welding.

Related reading: The 8 Strongest Types of Welds

Switch to TIG

There is only so much you can do to reduce spatter when you MIG weld. Even with the perfect machine settings, technique, and base metal, MIG produces spatter. If the appearance of the weld and complete elimination of spatter is needed, TIG welding is a better choice.

Gas-Tungsten-Arc-Welding-GTAW
TIG Welding

TIG welding doesn’t let you lay down beads as quickly as MIG welding. While the weld itself goes in slower, TIG welding saves you time cleaning up spatter. As with the other trade-offs in welding, you’ll have to decide whether you want to spend time laying down beads or cleaning up spatter.

Related reading: What is TIG Welding Used For? Why Choose TIG Welding?

Finishing Touches

Weld spatter is an inescapable part of MIG welding, but it doesn’t have to rule your life. You can limit spatter by adjusting your welder settings, welding with clean base metal and good filler wire, using proper technique, and practicing your welding. You can also use sprays or tape to keep the spatter from sticking. The last resort to eliminating spatter is the good old angle grinder. Still, if you’ve read this far, you are probably tired of grinding spatter.

The key to spatter reduction is to practice. Sketch up some plans (or download them), buy some parts, and get to welding. The more you weld, the better you’ll get at controlling spatter.

Recommended reading

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David Harper

David is the Co-Founder and Senior Editor at weldingtroop.com. 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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