How to get good TIG welds

What makes a good TIG weld?

This page is for a specific moment: you have the amperage from the settings chart, the machine is set the way the chart says, and the bead still comes out wrong. That is not a settings problem, and it is the most common place people get stuck on TIG.

The ordering below matters. Work top to bottom and stop at the first thing that is wrong, because each variable masks the ones under it — you cannot judge your torch angle through a contaminated tungsten, and you cannot judge your pedal control through a dirty joint.

One honesty note before any of it: Arc & Bead has not welded these joints. What follows is conventional published practice, with the standards and manufacturer guidance named at the bottom of the page. It is not a report of a test we ran.

1. Tungsten preparation — the one people change last

A TIG arc is directional because the electrode tip is a shape. Ruin the shape and the arc stops pointing where you aim it, which reads as a machine problem and is not one.

Grind it lengthways, not across. Grinding marks should run along the electrode toward the tip, not around it. Transverse marks give the arc a spiral path to follow and it wanders.

Use a wheel kept for tungsten only. This is the single biggest avoidable mistake. A wheel that has touched steel embeds particles in the tip, and the result is a spitting, erratic arc that people diagnose as everything else first.

Point it for DC, ball or truncate it for AC. For DC steel and stainless, a point roughly two to two and a half times the electrode diameter in length. For AC aluminum the tip naturally balls slightly in use, and a truncated point is the usual starting preparation.

If you touch the puddle, stop and regrind. Dipping the tungsten contaminates it instantly. Welding on through it drags that contamination into every inch that follows. Regrinding takes twenty seconds; the bead you save does not come back.

2. Base metal cleanliness — TIG is the least forgiving process there is

With no flux anywhere in the process, nothing floats contamination out of a TIG puddle. What is on the metal goes into the weld.

Bare metal, every time. Mill scale, paint, galvanising and plating all have to come off, past the weld area rather than up to it.

Degrease after you grind, not before. Grinding spreads oil around rather than removing it. Mechanical first, solvent second.

Aluminum needs its oxide removed mechanically. Aluminum oxide melts far hotter than the aluminum underneath it, so it sits on the puddle as a gray skin and stops fusion. A stainless wire brush kept exclusively for aluminum is the standard answer — and kept exclusively matters, because a brush that has touched steel will embed steel in the surface.

Use separate brushes per material. One for steel, one for stainless, one for aluminum. Cross-contamination here produces defects that look like technique problems.

3. Angles, arc length and rod position

The one that surprises people: TIG is pushed, with the torch tilted away from the finished bead and the rod fed in front. That is the opposite of flux-core and stick, which are dragged because they produce slag that has to stay behind the arc — push or pull on flux-core explains the rule. TIG has no slag, so the logic reverses: you push, and you feed the rod at the front where you can see it enter the puddle.

4. Pedal control — and the start-and-stop defects nobody warns you about

The foot pedal is the only control that acts during the weld. Every other setting is chosen before you strike and fixed until you stop, which is why pedal technique is most of what separates a good TIG bead from a correct one.

Ramp in rather than stamping on it. Cold metal takes more current to establish a puddle than hot metal takes to keep one. Come up to amperage, let the puddle form, then back off as the plate heats — otherwise the bead starts narrow and grows wider and hotter as you travel, which is the most recognizable beginner TIG bead there is.

Taper out at the end. This is the big one. Lifting your foot abruptly abandons a hot puddle, which shrinks as it solidifies with nothing feeding it. The result is a crater crack — a star-shaped crack in the middle of the end crater, and a genuine defect rather than a cosmetic one. Searches like "poor start stop in welding" are usually describing exactly this.

The fix is two things done together: feed one or two extra dabs of filler as you come off the pedal, and taper the current down over a second or so rather than cutting it. Fill the crater and cool it slowly.

Let the post-flow run. Do not move the torch away the instant the arc stops. The gas continues for a few seconds precisely to shield the cooling weld and the still-hot tungsten — pull away early and you oxidize both. On stainless you can see the difference as color.

Restart on top of the previous crater. When tacking or restarting a bead, start inside the end of the last one and travel forward. Starting ahead of it leaves a cold unfused gap.

5. Gas coverage

Correct flow, correct cup, and the discipline to let post-flow finish. Flow rate and cup size are covered in full on what gas for TIG welding, and the reason a cylinder is non-negotiable at all is does TIG welding need gas.

Two failure modes worth recognizing by sight. Too little flow gives a gray, sooty or blackened bead and a balling tungsten. Too much flow is the counter-intuitive one: it becomes turbulent at the cup and draws surrounding air into the shield, producing the same porosity you were trying to avoid. More gas is not better gas.

Draughts matter more than people expect. An open door or a fan aimed anywhere near the bench will strip the shield off the puddle, which is why TIG is an indoor, still-air process in a way flux-core is not.

Practice in the order that teaches you something

Run beads on scrap with no filler at all first. It isolates one skill — holding arc length and travel speed with the pedal — and you cannot learn it while also coordinating a rod.

Then add filler on flat plate, then an outside corner joint, then a T-joint fillet, then thinner material. Mild steel before stainless before aluminum, because aluminum adds AC, oxide removal and a much narrower heat window all at once. AC versus DC TIG covers why aluminum is a different problem, and welding projects by skill level sequences the practice.

If you are still choosing a machine, TIG welders for beginners is the roundup, and TIG welding for beginners is the honest version of what the learning curve costs.

Almost all of the above assumes you can change the current while you weld. If you are working at a fixed amperage, that is the thing to fix first — best TIG welders with a foot pedal covers which machines include one and why a torch-mounted control is the alternative.