Why Your TIG Welds Look Dirty & What to Do About It


It’s true that TIG welding is the most versatile method out there. It’s also true that it’s arguably the most challenging process to learn. Numerous issues can cause your welds to look ugly, but for every problem, there is a solution.

Why your TIG welds look dirty & what to do about it? While there are many potential issues to consider while troubleshooting the root cause of unsightly welds, most can be traced back to some common mistakes. Each of those mistakes fits under one of the following four main categories:

  1. Job Prep
  2. Gas Shield
  3. Overheating
  4. Material Specific Settings

There are a lot of parts and pieces in a TIG machine and a lot of different materials that you can weld with one.

On top of that, there are steps in job prep and elements of your technique where small changes can have nasty effects. Fortunately, all of the common problems have pretty simple fixes. Read on to learn more.

The Real Reason That Your Welds Look Dirty

TIG is an acronym for Tungsten Inert Gas. This process is also sometimes called GTAW or Gas Tungsten Arc Welding. I’m not telling you these things to show off my egghead credentials.

Each of those acronyms provides important clues about what is going wrong when your TIG welds don’t turn out as they should.

You see, when metal is superheated (like it is during welding), it is susceptible to the process of oxidation. To counteract the process of oxidation, TIG welders create a shield of inert gas around the point where the electrical arc is acting on the material being welded.

The gas shield allows the metal to cool in a pocket of the inert gas so that oxygen doesn’t get a chance to act on it until the metal is strong enough to fight back.

How Does Knowing That Help You Get Prettier Welds?

If you understand what sets TIG welding apart from other methods, then it’s easy enough to know that a lot of the problems you’ll encounter doing TIG work can be traced back to issues with overheating your material or problems with the gas shield around the point of action.

If you’re working on clean materials, with a torch that’s been set-up right, and a machine that is on the right settings for the material, and you’re still having problems – they’re probably due to one of these two factors.

Unless it’s your technique! But hey, we all had to start somewhere, and we’re all still learning. And actually, we’ll be discussing technique when we get to overheating.

Job Prep – Set Yourself Up for Success!

As we just said, if you wanted to, you could call job prep everything you do up to the moment you strike an arc. But checking your equipment for the causes of gas shield problems deserves special attention. Setting up your machine to avoid overheating on any material you work on does too.

In this section, we’ll look at cleaning your material before you begin welding, preparing your torch, and briefly go over filler rod selection.

You probably already know that cleaning the material you’re welding and the filler rod you’ll be using before you start welding is crucial to getting a robust and pretty weld. But do you actually do it?

Clean it Well, Clean it Right

There’s nothing more straightforward in the entire process of TIG welding than prepping your materials. It isn’t very much fun, and it takes some time to do it right, but it’s worth doing the right way every time. The difference it will make in your results is enormous.

Even though cleaning your materials is pretty simple, there are still some things you need to know to get it right. For example, a wire wheel is a great way to hand clean carbon steel but a terrible idea for aluminum. Knowing what solution to use on a given material is just as important.

Choose Your Weapon(s)

A torch is a torch is a torch, right? Not even close.

There is a lot to consider when setting up your torch. Taking the time to figure out the right set – and set it upright – will make it a whole lot easier to get welds that look sharp.

Give yourself enough options, and get to know what works best for a given project, in each of the following areas:

  • Tungsten: Choose the right width and file the right tip.
  • Cups, Collets, and Gas Lenses: It’s essential to have options. Some welders will tell you that they use a gas lens whenever possible. Others say they only use them on stainless. But if you don’t have choices in your kit, or you aren’t comfortable with the options you have, you’ll be working harder than you have to.
  • Filler Rod: Keep a stock of (at least) 4043 and 5356. Get a chart to help you remember when each one is the right choice.

Gas Shield – Go with the Flow!

There are a lot of factors that can have an impact on the gas shield around your arc.

  • Are you welding indoors or outdoors? The wind is the enemy of TIG welding.
  • Are you using the right gas for the material you’re welding?
  • Do you need a gas lens? If you’re welding stainless steel, the answer is yes! If you’re welding anything else, the answer is “sure, why not”!

One of the most important things to do if you suspect a gas shield problem is to troubleshoot your set-up from bottle to cup. Follow this checklist:

  1. Bottle – Is it clearly labeled? Is it the right gas? Is the bottle empty? Is the valve open? Is the regulator set?

It’s rare, but sometimes the problem is inside the bottle. You might have water contamination. You might have gotten a mislabeled bottle. You can ask your supplier to run a check or offer a replacement.

  • Leads – Check for leaks. Even a pinhole can make a difference. Also, consider the length. You can lose some of your flow over long leads and may need to adjust the flow rate.
  • Cup – Check for cracks. Consider going with a bigger cup or a gas lens. You might need to adjust the stick length of your Tungsten too.

Overheating – Some Like It Hot

Just like our discussion of gas shields, there are a lot of factors to consider about overheating problems. Some welders like to run as fast and as hot as they can. Others swear by “slow and steady wins the race.”

Until you’re consistently getting welds that you want to post on your social media profiles, you should probably stay on the straight and narrow path. Adjust your amperage so that it takes a couple of seconds of the arc before the material starts to puddle and proceed from there.

Knowing what amperage is best for various materials will go a long way toward solving any headaches that overheating is causing you. But there are some other factors to consider:

  • Technique: Are you holding the torch, the filler rod, or both at bad angles? This can contribute to overheating.
  • Speed: If you’re going to slow, you’re probably getting too much penetration. If you’re going to fast, you’re moving the gas shield past the point of work before it has cooled.
  • Arc Length: Try to maintain a 1/8” arc length for most jobs.
  • Don’t Dip the Tip: It happens to all of us occasionally. A junky tip will make it hard to control your arc. When it happens, stop and change or regrind your Tungsten.
  • Keep Your Filler Rod Inside the Gas Shield: This isn’t, strictly speaking, an overheating issue, but it’s important to remember and part of your overall technique that will help you get smooth and avoid overheating due to technique.

Material Specific Settings

This section could fill several volumes of an encyclopedia if we didn’t stick to the point of why we’re all here. Two widespread mistakes are related to specific materials that we need to mention before we wrap this up.

  1. Aluminum and Magnesium – Always weld on the AC setting.
  2. Everything Else – DC is where you want to be.

In Conclusion

There is a lot to keep track of in TIG welding. Overlooking any single thing, no matter how insignificant it might seem, can make it all but impossible to get welds that look good. If you know that you can lay a clean, steady bead, but you’re not getting the results you want, focus on the issues we’ve discussed and see if you don’t start to get better results.

Alexander Berk

A bit about myself: I am a certified international welding engineer (IWE) who worked in different welding projects for TIG, MIG, MAG, and Resistance Spot welding. Most recently as a Process Engineer for Laser and TIG welding processes. To address some of the questions I frequently got asked or was wondering myself during my job, I started this blog. It has become a bit of a pet project, as I want to learn more about the details about welding. I sincerely hope it will help you to improve your welding results as much as it did improve mine.

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