Weld spatter is a particularly unpleasant feature of welding because it occurs in patches and can be difficult to remove. It is a mixture of molten metal droplets, flux (usually), fire scale (oxides), dirt, and other metallic particles that are ejected during the welding process.
The cause of welding spatter can vary depending on your process and equipment setup. But there are some universal causes found across all modes of welding no matter your equipment or technique. In this article, we’ll explore the most common causes of welding spatter as well as some helpful tips to prevent it from happening in the future.
Table of Contents
Why is Weld Spatter Bad?
A weld spatter is bad because it can injure you and damage your base metal at the same time. In addition, it can contaminate melted weld puddle which leads to porosity in welds. Porosity in a weld means there are tiny holes scattered through it, which may weaken the weld itself.
Your remove the weld must spatter after welding. If you don’t, it can badly affect the quality of a finished weld and could adversely affect its integrity (the ability to bear loads) and service life (the length of time before replacement becomes necessary).
How to Remove Spatter
The easiest way is to use an angle grinder fitted with a coarse disk – one used for removing old paint or rust from metal surfaces. However, this can damage any surrounding metal.
A much better option would be to use an abrasive brush fitted to the grinder, which will happily remove the weld spatter without damaging the base metal in any way.
How to Prevent Spatter
First, you need to determine what’s causing the welding spatter. You need to make sure your wire is designed for a particular material and your current values and travel speed is correct.
If this isn’t done correctly too much filler wire will enter the joint, causing excess penetration and porosity in the weld.
Let’s take a closer look at each welding causes separately.
Common Causes of Welding Spatter
Welding spatter is caused by a variety of factors, which vary depending on the sort of material you weld and the methods you use to get the job done.
Material for Welding Cover
When it comes to preventing welding spatter, it can be as simple as choosing the correct material for your weld. If you do this, it can mean that you can worry less about welding spatter and other issues ocour.
The Weld Pool
The size and shape of the weld pool will vary depending on the material you are welding, along with a number of other factors. You need to be able to control the process and maintain appropriate parameters.
If you don’t maintain them, it’s more likely spatter will form and lead to problems such as porosity and weld contamination.
The position in which you carry out your welding can also affect the spatter you form. The most common welding positions are horizontal, vertical, and overhead. In each of these positions, different spatter issues can occur.
NOTE: In general, horizontal welding tends to produce more spatter than vertical, whereas doing your welding overhead will reduce the amount of spatter you have to deal with.
If you hold the electrode too far away from the workpiece, it won’t properly fuse the material together and will lead to material spattering as it starts to cool.
This typically occurs when the material is sticking out into your weld pool region, which can be an issue when you are welding material that is very thick.
Wrong Amperage Settings
Using excessive heat during your welding process can cause material to spatter. If you get the amperage setting wrong, it will melt material too quickly and material droplets will form on its surface.
Not using enough heat on the material can spatter as well because it isn’t adequately heated. As the material cools, it creates a build-up on the surface which is known as slag. This occurs when it’s not melted enough during welding.
If this happens you will need to increase the heat input or slow down your welding speed slightly.
NOTE: You must always make sure that you maintain optimal amperage settings at all times, especially when working on thin metals or following complicated curves which might result in unnecessary overheating of the workpiece if not precisely controlled.
Welding Too Quickly Without Allowing Cooling
When you weld material, you need to allow it time to cool between each weld. If you don’t, material produced during the welding process (spatter) will be too hot and turn into a solid mass before it hits the ground.
This is something that can cause issues for many different reasons:
- Weld contamination
- Joint penetration failure
- Poor weld appearance
- Weld burn through
- Material porosity
- Reduced coating adhesion
- Severely reduced material mechanical properties (eg. Tensile Strength).
- Excessive welding heat input which will ruin the heat treatment of the metal, ruining its metallurgical properties and making it more brittle.
If you want to avoid these issues, it’s important that you allow material to cool between welds so spatter can’t form. This is especially the case when welding thin metal materials such as stainless steel and other high alloy steels where one single weld can ruin the entire piece of work!
TIP: To prevent this you should avoid welding material too quickly or stopping every pass before material has time to solidify.
Welding in Windy Conditions
When the material is constantly moving (wind) it can lead to spattering across your work area. This is because the material that has molten spatter on its surface will blow around with the wind and come into contact with other material you are welding, ruining any seams which you have worked hard to fuse together during the design process.
TIP: You can reduce material spatter in windy conditions by using an anti-spatter spray
Incorrect Filler Materials
Using the wrong material for a filler material can also cause material to spatter. This is generally caused when material that isn’t compatible with the one being used to stick together, such as using stainless steel filler material for mild steel.
This can cause issues because it often doesn’t stick properly and will come loose from the workpiece, which causes it to fall onto the ground. It can also move around This can be problematic since it frequently fails to adhere adequately to the workpiece and comes loose, causing it to tumble to the ground.
It can also move around during the final welding steps, causing damage to the material’s shape and form, therefore the material filler material you’re using must be suitable with the materials you’re putting together.
TIP: To reduce material spatter caused by using an incompatible filler metal, always ensure you use material that is suitable for your purpose.
Using an Incorrect Shielding Gas Mixture
The shielding gas mixture must be set correctly for your material thickness, type, and welding equipment.
If you use a mixture that doesn’t match the needs of your material/welding equipment, you may experience spatter because it isn’t properly shielded from the atmosphere.
TIP: Always make sure you use material with an adequate level of shielding gas (typically 75%) and ensure that material flow rate is set at a suitable level for the material thickness being welded.
Too Much Shielding Gas
If material is given too much shielding gas, it can lead to being ejected from the If the material is exposed to too much shielding gas, it may be ejected from the weld puddle. This is due to the internal pressure created by the material within the weld puddle, which causes the material to be expelled.
TIP: To prevent this you should avoid using material more than necessary or ensuring material flow rate is set at a suitable level for the material thickness being welded.
Wrong Electrode Tip Angle
Different sections of one substance spatter and spray each other when you weld two materials together. Because the material from the material weld puddle is unable to exit, it spatters. It may also cause material to fall back into a material weld pool, reducing the weld joint’s strength over time.
This happens when electrode tip is too blunt or the clearance between the electrode tip and the material surface isn’t close enough.
TIP: Only use electrode tips that are appropriate for the metal you are welding and ensure you have a proper electrode tip to material surface contact which is neither too tight nor too loose.
Using Flux Cored Electrodes
Using flux core electrodes often produces more spatter than other types. This is because the flux coating on the electrode causes oxidation between materials, leading to high levels of oxidization which can be problematic when welding.
TIP: To reduce spatter caused by using flux cored electrodes you should not use too much shielding
Bad Arc Length
Make sure that the arc length (the distance between the metal and the electrode) is set properly. When you employ an arc length that is too long, the metal transfer rate is slowed, which might result in more spatter being created over time.
TIP: The correct arc length will depend on the metal thickness and type, but generally speaking the correct arc length will be when there is no visible spatter.
Incorrect Arc Polarity
The polarity of the electrode determines which direction the arc moves in relation to the workpiece. This is important because it affects your weld pool’s shape and size, which can cause spatter if it isn’t a good fit for your intended weld joint shape.
TIP: For most materials it is best to use DC-positive polarity, but you should always check with the manufacturer's recommendations for your material.
Not Using a Gas Lens
A gas lens is a special piece of equipment that ensures that adequate shielding gas protects your weld pool from oxygen and other elements in the atmosphere.
NOTE: Using a gas lens for material is key to ensuring your weld pool doesn't oxidize and spatter occurs.
If you put electrodes designed for heavier materials on thin-gauge steel, there may be a lot of spatter.
TIP: Always use electrodes that are designed for your material thickness and type, as well as your welding equipment.
Using Electrodes That Have Not Been Properly Stored
Electrodes that have been improperly stored may oxidize, resulting in spatter. This is because when electrodes come into touch with other materials or laser gas, their external coatings are destroyed, resulting in a reduction in alloying elements/impurities.
TIP: To reduce the risk of spatter, always store your electrodes properly.
Incorrect Travel Speed
Due to the lack of build-up, if you go at a fast pace, you may experience more spatter. This is because there isn’t enough time for the material to build up in one spot, resulting in molten metal being ejected from the weld pool at various angles.
TIP: To reduce spatter, always maintain a steady travel speed that is appropriate for your material thickness and type.
Mild Steel Flux for Arc Welding Stainless Steel
Using stainless steel flux cored weld electrodes on mild steel can result in a strong reaction, resulting in a lot of welding spatter. This is due to the electrode’s poor tempering over time, which causes micro fissures in the electrode covering.
TIP: To reduce spatter when welding stainless steel, always use electrodes that are designed for mild steel on mild steel.
Filler Rod is Too Large
Using a filler rod that is too large for the job at hand can cause you to get more welding spatter. This is because the weld pool will become very unstable, causing parts of it to spatter outwards due to the size of the electrodes.
TIP: To reduce spatter when using larger filler rods, always test their usage on a separate piece of material before using them for your intended welding application.
TIG Welding Aluminum with the Wrong Polarity
Using TIG welding to weld aluminum with the wrong polarity can cause very bad spatter due to it being DC-positive, which means no shielding gas will be used to protect the weld pool from atmospheric elements.
This is because the weld pool will become very oxygen-rich and so molten metal will be ejected from it at wayward angles.
TIP: To reduce spatter when welding aluminum, always use a gasless TIG welder for this application.
Excessive Moisture or Oxygen Content
Using a welding electrode that is exposed to too much moisture or oxygen can cause the weld pool to become oxidized, which will lead to lots of spatter being ejected from it.
This is because there isn’t enough alloying elements/impurities present in the weld pool as a whole to bring everything together and form one solid piece of steel.
TIP: To reduce the risk of spatter, always maintain a controlled work environment and ensure welding electrodes are stored in the right conditions.
Forced Air-Welding Aluminum
When forced air-welding aluminum, trying to use too high amperage can cause very heavy spatter as there isn’t enough heat to keep the weld pool hot. This is because the heat dissipates too quickly due to the lack of conductivity in aluminum, leading to a little molten metal being ejected from your weld pool.
TIP: To reduce spatter when forced air-welding aluminum, always use slightly lower amperages for this application.
Wetting Materials Before Welding
When two pieces of different materials are being welded, it is important to make sure that you use a welding electrode that has been designed for wetted materials.
Wetting the material before welding greatly increases the risk of spatter occurring because different metal ions form when in contact with water, leading to inferior properties.
TIP: To reduce the risk of spatter, always choose your welding electrodes wisely.
As you can see, there are many weld spatter causes that you need to be aware of. If you fail to take care of them all, your weld pool’s shape and size will not be correct and you will get spatter. With this article as a guide, you can make sure your weld pool is in good shape to reduce the risk of spatter.
Most causes are straight forward if you know what you’re doing, but it’s always recommended that you use electrodes designed for the thickness and type of material (and play it safe). If you don’t, your weld pool will be in a bad shape and this can lead to spatter.