TIG Tungsten Electrode Guide
Tungsten electrode selection for GTAW (TIG) — band colors (green / red / gray / gold / blue / purple / brown / orange), electrode composition, AC vs DC use, amperage capacity, and grinding angles.
Reference
TIG tungsten electrodes are color-coded by composition. Pure tungsten (green) is increasingly being replaced by lanthanated (gold / blue), ceriated (gray / orange), and zirconiated (white / brown) — they last longer, start easier, and work on AC and DC. Avoid 2% thoriated (red) in new shops — thorium is mildly radioactive and the dust is a real lung hazard during grinding. Lanthanated (1.5% / blue band) is the modern universal replacement.
Electrode color codes (AWS A5.12 / ISO 6848)
| Band color | AWS code | Composition | Best for | Use cases |
|---|---|---|---|---|
| Green | EWP | Pure tungsten 99.5% | AC only — aluminum, magnesium | Older Syncrowave-style transformers; balls up on tip; cheap. |
| Red | EWTh-2 | 2% thoriated tungsten | DC steel / stainless | Mildly radioactive — phase out for safer alternatives. |
| Yellow | EWTh-1 | 1% thoriated tungsten | DC steel — light duty | Same caveats as 2%; less common. |
| Gold | EWLa-1.5 | 1.5% lanthanated tungsten | AC and DC, EVERYTHING | Modern universal — replaces thoriated for most users. |
| Blue | EWLa-2.0 | 2% lanthanated tungsten | AC and DC, high amperage | Run hotter than gold — heavy industrial. |
| Black | EWLa-1.0 | 1% lanthanated tungsten | AC and DC, light duty | Less common; gold band more popular. |
| Gray | EWCe-2 | 2% ceriated tungsten | AC and DC — low amperage | Best for thin material / orbital welding; starts at low amps. |
| Orange | EWCe-2 alt | 2% ceriated (some makers) | AC and DC | Alternate gray; same composition. |
| Brown | EWZr-1 | 1% zirconiated tungsten | AC only — aluminum | Resists tungsten contamination of weld pool; balls cleanly. |
| White | EWZr-1 alt | 1% zirconiated alt | AC only — aluminum | Same as brown. |
| Purple | EWG E3 | Rare-earth tungsten (mixed) | AC and DC, demanding work | New formula; best edge holding; replaces thoriated. |
Amperage capacity by diameter
| Tungsten Ø | DCEN (steel/SS) max | AC HF (aluminum) max | AC SqWv max | Pure tungsten AC max |
|---|---|---|---|---|
| 0.020" (0.5 mm) | 5-15 A | 5-15 A | 5-20 A | 5-15 A |
| 0.040" (1.0 mm) | 10-70 A | 10-60 A | 15-80 A | 10-50 A |
| 1/16" (1.6 mm) | 60-150 A | 50-120 A | 70-160 A | 50-100 A |
| 3/32" (2.4 mm) | 140-235 A | 100-180 A | 150-260 A | 100-160 A |
| 1/8" (3.2 mm) | 225-325 A | 160-250 A | 230-340 A | 160-220 A |
| 5/32" (4.0 mm) | 300-400 A | 200-320 A | 300-420 A | 200-275 A |
| 3/16" (4.8 mm) | 380-525 A | 250-400 A | 380-550 A | 250-340 A |
| 1/4" (6.4 mm) | 500-700 A | 350-550 A | 500-720 A | 325-450 A |
Tungsten grinding — tip geometry
| Tip shape | Use | Grind angle | Notes |
|---|---|---|---|
| Pointed (sharp) | DC steel / stainless thin sections | 15° - 30° included | Concentrates arc; precise for sheet metal. Lasts longer with rare-earth doping. |
| Truncated (flat) | DC heavy steel / stainless | 30° - 45° + small flat (1× tungsten Ø) | Reduces arc wander at high amps. Re-tip when flat exceeds 1.5× Ø. |
| Balled | AC pure tungsten on aluminum | Pre-melt ball ≈ 1.0-1.5× Ø | Run small piece of scrap aluminum at low amps DCEP to form ball. Modern lanthanated/ceriated should NOT be balled. |
| Pointed (modern AC) | AC lanthanated / ceriated aluminum | 20° - 30° | Keep pointed; no ball. Sharp tip preserves arc focus on AC SqWv inverters. |
Grind direction matters
- Always grind tungsten longitudinally (parallel to electrode axis), not radially. Radial grind marks cause arc to wander.
- Use a dedicated tungsten grinder wheel — never grind tungsten on the same wheel used for steel or aluminum (cross-contamination kills arc starts).
- For thoriated tungsten: use a wet grinder, downdraft table, or HEPA dust collection. Wear N95+ respirator. Wash hands after handling. Do not grind in shop areas where food/drink is present.
- Diamond cup wheels work cleanest — no contamination, no airborne particles. Worth the $40-60 investment.
- Replace the tip the moment the tungsten contaminates the puddle (silver/blue blob on tip = tungsten in weld). Re-grind 1/4"-3/8" past the contamination.
Common mistakes & fixes
| Symptom | Cause | Fix |
|---|---|---|
| Arc wanders / dances around joint | Radial grind marks on tip | Re-grind longitudinally with longitudinal wheel marks. |
| Tungsten splits or shatters | Wrong electrode for AC; using sharp pure tungsten on AC | Switch to lanthanated/ceriated, or pre-ball pure tungsten before AC. |
| Hard to start the arc | Contaminated tip / wrong electrode | Re-grind; switch to ceriated (gray) for low-amp starts. |
| Black smoke / sooty weld | Tungsten too small for amperage; melting | Step up to next larger diameter electrode. |
| Tungsten melts / balls on DC | Polarity reversed (DCEP) — hot for tungsten | Switch to DCEN. DCEP only used briefly for cleaning aluminum on AC SqWv. |
| Grayish weld surface (aluminum) | Insufficient AC cleaning balance | Increase EP (electrode positive) percentage to 30-40% for cleaner. |
| Tip immediately contaminates | Touch-start on dirty material | Use HF or lift-arc start; clean joint to bright metal first. |
AC balance reference (modern square-wave inverters)
- 70% EN / 30% EP
- Standard aluminum starting point. Good cleaning + reasonable penetration.
- 80% EN / 20% EP
- Heavier penetration, less cleaning. Use on already-clean aluminum.
- 60% EN / 40% EP
- More cleaning action — used on oxidized / weathered aluminum or castings.
- 50/50
- Old transformer welder fixed default. Lots of heat into tungsten — needs larger electrode.
- AC frequency
- 60-120 Hz for general work. Higher freq (200-400 Hz) tightens arc cone, gives narrower bead. Used for thin / precision work.
Quick selection guide
- Welding 1/8" mild steel DC
- 3/32" lanthanated (gold or blue), pointed at 30°, 100-150 A.
- Welding 1/8" stainless DC
- 3/32" ceriated (gray), pointed at 25°, 80-120 A.
- Welding 1/8" aluminum AC
- 3/32" lanthanated (gold) or ceriated (gray), pointed at 25°, 130-160 A AC, 70/30 balance.
- Welding sheet metal (< 1/16")
- 1/16" ceriated (gray), pointed sharp, 30-60 A.
- High-amp aluminum > 3/8"
- 1/8" or 5/32" zirconiated (brown) or lanthanated, balled / blunt, 200-300 A AC.
- Pipe / orbital
- 1/16" or 3/32" ceriated (gray) — best low-amp starts.
Why thoriated tungsten is being phased out
- Thorium-232 is a low-level alpha-emitting radioactive isotope (half-life 14 billion years). Bulk electrodes are not dangerous to handle.
- The hazard is in grinding dust: thorium oxide particles inhaled during grinding can lodge in the lungs and emit alpha radiation locally for decades. NIOSH classifies it as a confirmed lung carcinogen.
- Modern lanthanated, ceriated, and rare-earth (purple) tungstens match or exceed thoriated performance with no radioactivity.
- Many countries / manufacturers have banned thoriated for new aerospace / nuclear / medical work. Many shops have transitioned by 2025.
- If you must use thoriated: wet grind, full HEPA, respirator, washable clothing, never eat/drink in grinding areas.
Notes
- Color codes per AWS A5.12 / ISO 6848. Some manufacturers use slightly different bands — verify against the label, not just the color.
- Amperage ranges are typical maximums for sustained welding; brief peaks (HF start, pulse peaks) can exceed listed values briefly.
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