Tungsten electrodes: which type for which job?
Gold, green, grey, red – the colour codes of TIG tungsten electrodes explained: alloy, current type and when each type is worth it.
Tungsten electrodes carry a colour code at the tip that identifies the added alloy (DIN EN ISO 6848). The right type determines ignition, service life and weld quality. This overview shows which colour suits which material and current type.
What the colour code means
The colour ring at the electrode tip identifies the oxide added to the pure tungsten. This oxide improves ignition, arc stability and service life compared with pure tungsten. The marking is standardised in DIN EN ISO 6848.
The main types at a glance
WL15 (gold) – 1.5% lanthanum oxide. The all-rounder: easy ignition, long service life, for DC and AC, non-radioactive. First choice for most jobs. WP (green) – pure tungsten. Classic for AC welding of aluminium and magnesium; forms the typical balled tip. WC20 (grey) – 2% cerium oxide. Excellent at low currents and DC, also AC; non-radioactive, a popular thorium replacement. WT20 (red) – 2% thorium oxide. Very good ignition and service life on DC/steel, but slightly radioactive – increasingly replaced by WL/WC. WZ8 (white) – 0.8% zirconium oxide. For AC aluminium when maximum weld purity is required.
Which current type suits which electrode
For steel, stainless steel and most DC work, WL15 (gold) and WC20 (grey) are the safe choice. For aluminium and magnesium on AC, WP (green) and WZ8 (white) are suitable because they hold the balled tip needed for AC. WL15 works on both DC and AC and is therefore the practical all-rounder.
Diameter and tip preparation
The diameter depends on the current: the higher the current, the thicker the electrode. On DC the tip is ground lengthwise (a pointed grind gives a stable, focused arc); on AC the tip is balled. A clean, lengthwise grind noticeably improves ignition and bead appearance.
Frequently asked questions
Which tungsten electrode is best for stainless steel?
For stainless steel on direct current (DC), WL15 (gold) and WC20 (grey) are the common choice: easy ignition, stable service life and non-radioactive.
Are thoriated (red) electrodes still allowed?
WT20 (red) is slightly radioactive. They are not banned, but for occupational-safety reasons they are increasingly replaced by lanthanum (WL) or cerium (WC) electrodes, which offer comparable properties without radioactivity.
Which electrode do I use for aluminium?
Aluminium is welded with alternating current (AC). WP (green) and WZ8 (white) are suitable; WL15 (gold) can also be used for AC.
How do I choose the right diameter?
The diameter depends on the current: higher currents need thicker electrodes. As a guide, choose the electrode so it operates in the upper part of its permissible current range.
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