TIG (GTAW) is a precision arc welding process that uses a non-consumable tungsten electrode to create the arc while a filler rod is added by hand. It produces the cleanest, most controlled welds of any arc process, at the cost of speed.

Which tungsten electrode should I use?

Lanthanated (blue EWLa-2) is the best all-rounder for AC and DC. Ceriated (gray EWCe-2) runs well on low-amperage DC. Thoriated (red EWTh-2) is classic DC-only. Zirconiated (white EWZr-1) resists contamination on AC. Pure tungsten (green EWG) is cheapest but carries low current.

Why is my TIG weld turning black or oxidized?

The puddle was exposed to air — usually low gas flow, wrong gas for the metal, drafts blowing the shield away, too long an arc, or travel too fast for the gas flow rate. Black soot on aluminum often means AC balance is set wrong.

What shielding gas is used for TIG welding?

Pure argon for steel, stainless, and aluminum up to about 1/4 inch. For thicker aluminum, 25/75 or 50/50 argon/helium mixes add heat. Helium alone is used for heavy copper and thick plate. Never use CO2 — it destroys the tungsten.

Why is my tungsten electrode melting or balling up?

Wrong polarity (DCEP instead of DCEN), too much amperage for the tungsten size, contaminated tungsten touching the puddle, or running on CO2-rich gas. A balled tip on DC is a sign of reversed polarity.

Can TIG weld thin sheet metal?

Yes — TIG is the best process for thin sheet. With pulse and a small tungsten you can weld 24 gauge and down to foil thickness with 5-10 amps. It is why TIG dominates sanitary stainless and aerospace work.

Do I need a foot pedal for TIG welding?

Not to start. A pedal gives live amperage control, which helps on out-of-position joints and thin material. Many inverters also have a torch thumb control, and fixed amperage works fine for practice and production strings.

TIG Welding (GTAW) | ALL ABOUT WELD

Q: When do I use AC vs DC for TIG welding?

DCEN (electrode negative) is the default for steel, stainless, and titanium — most heat goes into the work. AC is required for aluminum and magnesium because the positive half-cycle scrubs the oxide film off the surface.

WHAT IS TIG?

TIG (Tungsten Inert Gas, formally GTAW) uses a tungsten electrode that does not melt into the weld. The arc runs between the tungsten and the work while a stream of inert gas — almost always argon — shields the arc and puddle. Filler metal, when needed, is fed into the puddle by hand as a rod.

Because current and filler are controlled independently, the welder can run very low amperage, lay down clean beads with no slag and almost no spatter, and weld metals no other process handles well — aluminum with AC, thin stainless, titanium, and exotic alloys. The trade-off is speed: TIG is two to three times slower than MIG and demands a steady hand.

AC + DC polarity options

0.5 mm clean thin sheet

1–300 A current range

STARTING PARAMETERS

Fine-tune from here — every machine and joint varies.

Material	Filler	Tungsten	Polarity	Amps	Argon cfh
1/16 in steel	ER70S-6	1.6 mm EWLa-2	DCEN	45–70	15–18
1/8 in steel	ER70S-6	1.6–2.4 mm	DCEN	90–130	15–20
1/4 in steel	ER70S-6	2.4 mm	DCEN	150–200	18–25
1/8 in stainless	ER308L	1.6 mm	DCEN	80–110	15–18
1/8 in aluminum	ER4043	2.4 mm	AC	150–170	18–22
1/4 in aluminum	ER5356	3.2 mm	AC	200–250	20–25

AC vs DC — QUICK PICK

Setting	Use for	Why
DCEN	Steel, stainless, titanium	Deep penetration, no arc cleaning, narrow bead
AC	Aluminum, magnesium	Positive half-cycle scrubs the oxide film
DCEP	Almost never	Melts the tungsten — avoid

AC balance, usually 60–70% EN, lets you tune how much time the arc spends cleaning vs penetrating on aluminum.

HOW TIG WORKS

The tungsten carries current without melting. The gas cup and lens shape a laminar shield around the arc, and the welder adds filler rod with the free hand. Everything is manual — heat, arc length, and filler feed — which is why TIG looks effortless only after hundreds of hours.

01

SHARPEN TUNGSTEN

Grind longitudinally to a 30–35° taper on a dedicated wheel — contaminated wheels ruin the arc.

02

SET POLARITY

DCEN for steel and stainless, AC for aluminum. Set balance and frequency for aluminum.

03

FLOW ARGON

15–20 cfh through a #6–#8 cup. A gas lens gives a wider, calmer shield for aluminum.

04

START THE ARC

Lift-start or high-frequency start — never scratch the work with the tungsten.

05

MELT THE PUDDLE

Hold a 3–6 mm arc, torch tilted 15–20° in the direction of travel. Watch the puddle form.

06

DIP FILLER

Dip the rod into the leading edge of the puddle — not the arc — and pull it back.

07

ADVANCE STEADY

Move 2–3 mm per dab at a constant rhythm. Irregular travel makes a rippled, uneven bead.

08

POST-FLOW

Keep gas flowing 5–10 seconds after the arc stops to protect the hot tungsten and crater.

EQUIPMENT REQUIRED

AC/DC Inverter

A square-wave AC/DC machine for steel and aluminum. Single-phase 200 A covers most work.

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TIG Torch

Air-cooled 17/26-series for general work; water-cooled for long runs at high amperage.

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Gas Lens & Cup

Collets, collet bodies, and ceramic cups from #4 to #10. Gas lens for aluminum.

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Foot Pedal

Live amperage control for out-of-position and thin work. Torch thumb switch is an alternative.

Argon Supply

Pure argon with a two-stage regulator and flowmeter. One full cylinder lasts most hobbyists months.

Tungsten Grinder

A dedicated bench grinder with a fine wheel, or a handheld rotary tool with diamond bit.

Fume Extraction

TIG fume is lower volume but real — on-gun capture keeps you out of it on stainless.

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PPE

Auto-darkening hood at shade 9–13, dry leather gloves, and a long-sleeve shirt for UV.

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CONSUMABLES & FILLER

TUNGSTEN ELECTRODES

Color band on the ground end tells you the alloy.

Class	Band	Best for
EWLa-2 (1.5% La)	Blue	Best all-rounder — AC and DC
EWCe-2 (2% Ce)	Gray	Low-amp DC, thin stainless
EWTh-2 (2% Th)	Red	DC steel — radioactive dust, grind wet
EWZr-1 (Zr)	White	AC — resists contamination
EWG (pure)	Green	Cheap AC, low current only

Amperage capacity scales with size — 1.6 mm handles ~120 A DC, 2.4 mm ~200 A, 3.2 mm ~300 A.

FILLER RODS

Match the filler to the base metal — never stronger than the base for welding.

Base metal	Rod	Note
Carbon steel	ER70S-6	Deoxidized, forgiving
Stainless 304	ER308L	Low-carbon avoids sensitization
Aluminum 6061	ER4043	Softer, crack-resistant
Aluminum 5083/5052	ER5356	Stronger, anodizes to match
Copper pipe	ERCu	Needs preheat, helium helps

Rod diameters 1.6 mm and 2.4 mm cover nearly everything. Store rods dry and clean — oil and fingerprints cause porosity.

SHIELDING GAS

100% Argon

The standard for steel, stainless, and aluminum up to 1/4 in. Clean, stable arc at low flow.

Argon/Helium Mix

25/75 or 50/50 Ar/He for thick aluminum and copper — helium adds heat and travel speed.

100% Helium

Heavy-section copper and thick plate. High flow rates needed — the arc is hotter and harder to control.

Never CO₂ or oxygen mixes — they oxidize the tungsten and destroy the arc. Back-purge stainless with argon when full-penetration weld quality matters.

WELDING POSITIONS

TIG welds in every position. Amperage and filler rhythm change, but the core discipline — keep the puddle where you want it — is the same everywhere.

FLAT

Easiest — the puddle sits where you put it. Best place to learn dabbing and stringers.

HORIZONTAL

Drop 10–15% amperage. Keep the torch level and let the puddle crown before advancing.

VERTICAL UP

Drop amps 20%, use a short arc, and dab fast. Pulse helps control the puddle against gravity.

OVERHEAD

Lowest amperage and smallest filler dabs. Mirrors help — never weld overhead without a hood.

JOINT PREPARATION

TIG rewards clean metal. Whatever the process tolerates, TIG magnifies — so preparation is the difference between a weld you photograph and one you grind off.

CLEAN BOTH SIDES

Degrease with acetone or solvent, then wire-brush or flap-disc within a few inches of the joint. Contaminants boil into porosity.

FIT-UP & GAP

Tight joints are TIG's strength. Square edges on thin sheet, 60–70° included angle with a root face on plate.

BACK PURGE

Stainless and titanium need argon on the root side — otherwise the back bead oxidizes into a sugar-like crust.

TUNGSTEN PREP

Grind to a point on a dedicated wheel, never a rusty one. Re-grind after any contamination.

BEVEL ON PLATE

Above 3/16 in, bevel and root-open to reach full penetration without running excess heat.

TACK & CLAMP

Tack every 2–4 in and clamp to control gap. Aluminum moves — tack and weld quickly to beat distortion.

WELDING TECHNIQUES

Six techniques that cover most TIG work. Master the first two before touching the rest.

STRINGER BEADS

Straight travel, no weave, constant speed. The foundation — clean and reproducible on any metal.

DABBING FILLER

Dip the rod into the puddle's leading edge and withdraw. Short, even dabs build a ripple pattern.

WALKING THE CUP

Rest the cup on the metal and rock it side to side. Pipe welders use it for steady out-of-position beads.

PULSE TIG

Background current holds the arc while peak current melts — thin sheet, out-of-position, and consistent dabs get easier.

AC BALANCE & FREQUENCY

Higher EN% = more heat and a narrower bead; lower = more cleaning. Frequency above 100 Hz tightens the arc on aluminum.

MULTIPASS

Clean between passes with a stainless brush, and let interpass temperature stay below 300°F on stainless to avoid sensitization.

UNDERSTANDING YOUR PARAMETERS

In TIG the welder is the machine's software. These six numbers are what you adjust — and why.

AMPS

The master knob. Amperage sets penetration and puddle size. Too high burns through thin metal; too low makes a skidded bead that never fuses.

AC BALANCE

Only on AC. Higher EN% (60–75%) means deeper penetration, less cleaning and a narrower shiny band. Lower means more oxide scrubbing.

FREQUENCY

AC pulses per second. 60 Hz is soft and wide; 120–250 Hz pinches the arc for corner joints and thinner aluminum.

TRAVEL

Speed sets bead width and penetration. Move when the puddle is the size you want — steady rhythm beats any formula.

TORCH ANGLE

15–20° push angle directs heat forward. Steeper angles narrow the bead; dragging puts the shield behind and lets air in.

ARC + GAS

Keep arc length 3–6 mm — longer arcs overheat tungsten and lose shielding. 15–20 cfh argon, more with helium or in drafts.

ADVANTAGES & LIMITATIONS

ADVANTAGES

Precise heat control down to a few amps — welds foil to heavy plate
Cleanest weld appearance — no slag, almost no spatter
Welds aluminum, stainless, titanium, copper, and exotic alloys
Filler is optional — autogenous welds on thin joints
No smoke generation during the arc — cleaner work environment
Independent current and filler control for perfect root passes

LIMITATIONS

Slow — 2–3× slower than MIG on the same joint
Steep learning curve — two hands plus foot control
Ultraviolet output is intense — long-sleeve protection required
Contamination-sensitive — dirty metal welds terribly
Cost — AC/DC inverter plus argon adds up
Not for heavy structural steel — FCAW and SAW dominate production

INDUSTRY APPLICATIONS

Where code, cosmetics, or thin material matter, TIG is the process on the print.

Aerospace

Titanium and exotic alloys, often with orbital automation. Zero tolerance for porosity.

Food & Dairy

Sanitary stainless with purged, smooth beads that polish clean and hold no bacteria.

Nuclear & Pressure

Code roots on pipe and vessel work — often TIG root, FCAW fill.

Automotive Custom

Thin steel chassis, exhausts, and aluminum fab where appearance sells the build.

Art & Sculpture

Visible welds are part of the piece — TIG leaves them worth showing.

Piping & Tubing

Root passes in pipe welding, often hand TIG followed by fill passes.

Aluminum Fabrication

Boat, trailer, and structural aluminum where MIG porosity won't fly.

Medical Devices

Too many amps on thin gauge, slow travel, or a big filler dab.

Prevention

Drop amps, travel faster, and use pulse to protect thin sheet.

Full Defect Library

TIG SAFETY

TIG's UV output is among the strongest of any arc process, and the tungsten brings its own hazards.

ARC EYES & UV

Shade 9–13 hood, always down before striking. Nearby skin needs full coverage — TIG UV burns like sunburn.

TUNGSTEN DUST

Thoriated tungsten is radioactive — grind with water and never take the dust home. Lanthanated avoids the issue.

HIGH-FREQUENCY

HF start can interfere with pacemakers and electronics — keep a distance and use lift-start when possible.

ELECTRIC SHOCK

High open-circuit voltage. Dry gloves, dry boots, and never weld on damp floors or in wet clothes.

FUMES

Stainless and aluminum fume is toxic — ventilate or extract. Zinc-coated metal must be stripped first.

FIRE WATCH

Clear flammables, keep an extinguisher within reach, and watch for sparks behind partitions.

GAS CYLINDERS

Chain cylinders upright, cap them when moving, and shut the valve when done.

HOT METAL

The tungsten and work stay hot for minutes after the arc — mark it and let it cool.

STANDARDS & SPECIFICATIONS

The documents behind TIG practice, electrodes, and qualification.

Standard	Covers
AWS A5.12	Tungsten electrode classification and color coding
AWS A5.18 / A5.28	Solid filler wire for carbon and low-alloy steel
AWS A5.9 / A5.10	Stainless and aluminum filler rods
AWS D1.1 / D1.2 / D1.6	Structural steel, aluminum, and stainless welding codes
ASME Section IX	Welder performance qualification for pressure equipment
ISO 14175	Shielding gas classification
AWS B2.1	Procedure and performance qualification standard
ISO 2553	Symbols for welded joints on drawings

FREQUENTLY ASKED QUESTIONS

The questions every new TIG welder asks — answered straight.

What is TIG welding?

TIG (GTAW) uses a non-consumable tungsten electrode to strike the arc while filler rod is added by hand. It produces the cleanest, most controlled welds of any arc process — at the cost of speed.

When do I use AC vs DC?

DCEN (electrode negative) for steel, stainless, and titanium — most heat goes into the work. AC is required for aluminum and magnesium: the positive half-cycle scrubs the oxide film off the surface.

Which tungsten should I use?

Lanthanated (blue EWLa-2) is the best all-rounder. Ceriated (gray) for low-amp DC. Thoriated (red) is classic DC-only. Zirconiated (white) resists contamination on AC. Pure tungsten (green) is cheapest but weak.

Why is my weld turning black or oxidized?

The puddle was exposed to air — low gas flow, drafts, too long an arc, or travel faster than the shield. Black soot on aluminum usually means AC balance is set too electrode-negative.

What shielding gas do I need?

Pure argon for steel, stainless, and aluminum up to about 1/4 in. Argon/helium mixes add heat for thick aluminum and copper. Never CO₂ — it destroys the tungsten.

Why is my tungsten melting?

Wrong polarity (DCEP instead of DCEN), too much amperage for the tungsten size, contaminated tungsten, or a CO₂-containing gas. A balled tip on DC means reversed polarity.

Can TIG weld thin sheet?

Yes — it is the best process for thin sheet. With pulse and a small tungsten you can weld 24 gauge and below at 5–10 amps. That is why TIG dominates sanitary and aerospace work.

Do I need a foot pedal?

Not to start. A pedal gives live amperage control that helps out-of-position and thin work. Many inverters offer a torch thumb control, and fixed amperage is fine for practice.

RELATED PROCESSES

MIG / GMAW FCAW Stick / SMAW Plasma / PAW

NEXT TOPICS

Amperage Guide Electrode & Wire Selection Shielding Gas Flow Material Thickness Articles & Guides

VIDEO LIBRARY

Watch the technique sections — dabbing, walking the cup, and AC aluminum — demonstrated on real metal.

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A shop-floor cheat sheet with the parameter table, tungsten chart, and gas quick reference.

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TIG WELDING (GTAW)