TIG welding uses a non-consumable tungsten electrode to create an arc that melts the base metal, while you manually feed a separate filler rod into the molten puddle with your other hand. It produces the cleanest, most precise welds of any arc welding process, with no sparks or spatter, but it demands more coordination and practice than MIG or stick welding. Here’s how to set up your machine, hold the torch, feed filler metal, and troubleshoot the problems you’ll encounter along the way.
Choose the Right Polarity
Your first decision is whether to weld on DC (direct current) or AC (alternating current), and the answer depends entirely on what metal you’re welding.
DC electrode negative (DCEN) is the standard for steel, stainless steel, nickel alloys, copper, and titanium. The arc stays focused and stable, giving you a narrow, deep weld puddle that’s easy to control. Nearly all beginner TIG welding happens on DC with mild steel or stainless.
AC is required for aluminum and magnesium. These metals form a tough oxide layer on their surface that melts at a much higher temperature than the metal underneath. The AC cycle alternates between electrode negative (which provides penetration) and electrode positive (which breaks up that oxide layer). If you try welding aluminum on DCEN, the oxide never gets cleaned away, and your filler metal mixes with partially melted oxide to create a contaminated, weak bead.
Select Your Tungsten Electrode
Tungsten electrodes are color-coded by their alloy content, and different alloys perform better on different metals and polarities.
- Green (pure tungsten): Best for AC welding on aluminum and magnesium. Forms a clean, rounded ball at the tip and provides stable arc performance with AC sine wave machines.
- Red (2% thoriated): A popular choice for DC welding on steel, stainless, nickel, and titanium. Holds a sharp point well and starts easily. Also works for specialty AC applications on thin aluminum under 0.060 inches.
- Orange (2% ceriated): Performs best at low DC amperage on steel, stainless, nickel alloys, and titanium. A good general-purpose option that also works on AC.
- Gold (1.5% lanthanated): Maintains a sharp point exceptionally well, making it versatile for both DC and AC square wave welding on steel and stainless.
- Brown (zirconiated): Designed exclusively for AC welding. Resists contamination and holds a balled tip, but should never be used on DC.
For a beginner working on steel with DC, a red or gold tungsten in 3/32-inch diameter is a solid starting point. Grind the tip to a point on a dedicated grinding wheel, tapering it to roughly 2 to 2.5 times the electrode diameter in length. For AC aluminum work, let the tungsten form a small ball naturally when you strike the arc.
Set Up Your Shielding Gas
TIG welding requires an external shielding gas to protect the molten puddle from atmospheric contamination. Pure argon is the standard gas for nearly all TIG applications, on both steel and aluminum. For thick aluminum where you need deeper penetration, an argon/helium mixture or pure helium can help, but straight argon covers the vast majority of work.
Set your flow rate between 15 and 25 cubic feet per hour (CFH) for most joint types and cup sizes. Too little gas leaves the puddle exposed to air, causing porosity (tiny holes in the weld). Too much gas creates turbulence that actually pulls air into the shielding envelope, producing the same contamination you’re trying to prevent. If you’re welding outdoors or near a fan, you may need to increase flow slightly or set up a wind screen.
Dial In Your Amperage
Amperage controls how much heat goes into the metal. The right setting depends on the material type, thickness, and joint configuration. Most TIG machines come with reference charts, and manufacturer calculators (like Miller’s online TIG calculator) let you plug in your material and thickness to get a starting range.
As a rough guideline for steel, figure about one amp per thousandth of an inch of material thickness. So 1/8-inch (0.125-inch) steel needs roughly 125 amps. Aluminum requires more amperage because it conducts heat away quickly. These are starting points; you’ll fine-tune based on what the puddle looks like.
Use a foot pedal or fingertip amperage control whenever possible. This lets you vary heat in real time, ramping up to establish the puddle and backing off as the metal heats up along the joint. A ceramic cup on the torch works for anything under 250 amps. If you’re welding above 200 amps regularly, a water-cooled torch keeps the handle from overheating.
Hold the Torch Correctly
Grip the torch like a large pencil, resting it comfortably in your hand with enough control to make small, steady movements. Your torch hand controls arc length, travel speed, and the angle at which heat enters the joint.
Start with a travel angle of about 15 degrees from vertical, tilting the torch so the electrode points forward in the direction you’re moving. This slight tilt gives you a clear view of the puddle and leaves room to feed filler rod from the opposite side. Avoid steep angles of 45 degrees or more, which reduce gas coverage and stretch the puddle into a long, narrow shape that’s hard to control.
The work angle (how the torch is oriented across the joint) matters too. On a butt joint where two flat pieces meet edge to edge, hold the torch at 90 degrees to the surface. On a fillet weld, where the pieces form an L or T shape, angle the torch to about 45 degrees so heat reaches both surfaces equally. When joining metals of different thickness, cheat the angle slightly toward the thicker piece since it needs more heat to reach melting temperature.
Control Your Arc Length
Arc length is the distance between the tungsten tip and the workpiece, and keeping it tight is one of the most important skills in TIG welding. Aim for 1/8 inch to 3/16 inch. A short, controlled arc concentrates heat into a small area and gives you a narrow, well-defined puddle. A long arc spreads heat over a wider zone, reduces penetration, and can cause the weld to wander.
The challenge is maintaining that distance consistently while you move along the joint and dip filler rod. If the tungsten touches the base metal or the filler rod, it contaminates the electrode, and you’ll need to stop, regrind the tip, and restart. This is the most common frustration for beginners, and the only real fix is practice. Rest your hand or forearm on the workpiece (with a welding glove) to create a stable pivot point, and focus on smooth, deliberate movements.
Feed the Filler Rod
Your non-torch hand holds the filler rod at a low angle, feeding it into the leading edge of the puddle with a rhythmic dipping motion. The tip of the rod should stay inside the shielding gas envelope at all times. If you pull it too far away between dips, the hot end oxidizes and introduces contamination into the next dip.
The basic rhythm works like this: move the torch forward slightly to advance the puddle, then dip the filler rod into the front edge of the puddle, withdraw the rod just enough to clear the puddle, and advance the torch again. Each dip adds a small, consistent amount of filler metal that forms the characteristic stacked-coin pattern of a good TIG weld. Adding too much filler at once creates a tall, ropy bead. Adding too little leaves an undercut or concave profile.
Before you add filler at all, practice running the torch along a piece of scrap to melt a line without any rod. Get comfortable controlling the puddle size, travel speed, and arc length with one hand before you introduce the coordination of the second hand. This single exercise will accelerate your learning more than anything else.
Prepare Your Metal Properly
TIG is far less forgiving of dirty metal than MIG or stick welding. Mill scale, rust, oil, grease, and oxide layers all contaminate the puddle and weaken the finished weld. Before welding, clean the joint area with a stainless steel wire brush, acetone, or both. Use a brush dedicated to the metal you’re working on (don’t use the same brush for steel and aluminum). Clean the filler rod too, since contaminants on the rod transfer directly into the weld.
For aluminum, even freshly cleaned surfaces re-form an oxide layer within minutes of exposure to air. Clean immediately before welding. When welding on AC, don’t add filler rod too early after striking the arc. Let the AC cleaning action break down the oxide layer first, then begin dipping filler once you see a shiny, fluid puddle. Adding filler before the oxide is cleared traps contaminants in the weld.
Troubleshooting Common Problems
Porosity
Small holes or a spongy texture in the weld almost always point to gas coverage issues or contamination. Check that your gas is flowing, the flow rate isn’t set too high or too low, and no drafts are disrupting the gas shield. If the metal itself is the problem, you’ll usually see it immediately as the puddle behaves erratically or produces tiny bubbles.
Lack of Fusion at the Root
If the weld sits on top of the joint without melting into the base metal at the root, the likely causes are poor fit-up (a gap that’s too wide or too narrow), holding the torch too far from the joint, or feeding filler rod in a way that cools the puddle before it penetrates. Tighten your arc length, slow down, and make sure the puddle is fully molten before adding filler.
Tungsten Contamination
When the tungsten touches the puddle or filler rod, it picks up material that disrupts the arc. You’ll see an unstable, wandering arc and dark specks in the weld. Stop, snap off the contaminated portion of the tungsten or regrind it to a clean point, and restart. On AC, if you notice brownish oxidation or black pepper-like flakes in the puddle, your AC balance setting may need adjustment. Decrease the balance to increase the electrode positive portion, which improves oxide cleaning.
Excessive Tungsten Balling
On AC, some balling at the tungsten tip is normal and expected. But if the ball grows oversized and unstable, your balance setting is sending too much current through electrode positive. Reduce the EP percentage. A tungsten that erodes quickly or looks “bald” is also a sign of too much EP time.
Practice Exercises for Beginners
Start with flat steel plate, 1/8 inch thick, using DCEN and a red or gold tungsten ground to a point. Run straight lines across the plate without filler, focusing on a consistent puddle width and steady travel speed. Once you can lay a straight, even melt line, add filler rod and practice the dip-and-advance rhythm.
Move to butt joints next, tacking two flat pieces together and welding the seam. Then progress to T-joints and fillet welds, which introduce the 45-degree work angle. Each joint type teaches a different aspect of heat control and torch positioning. Aluminum is a significant step up in difficulty because it conducts heat so aggressively and requires AC, so save it until your steel technique is consistent.