Which designation corresponds to 1% Lanthanum Tungsten?

• A. EWLa-1 = 1% Lanthanum Tungsten
• B. EWG = Alloy not specific
• C. EWCe-2 = Cerium Tungsten
• D. EWTh-1 = 1% Thorium Tungsten

Answer: (A)

In GTAW electrode designations, the prefix EW identifies a tungsten electrode. The letters that follow indicate the alloying element, and the number after the dash shows the percentage of that element by weight. So La stands for Lanthanum and -1 means 1% lanthanum oxide is added. Put together, EWLa-1 represents a 1% Lanthanum Tungsten electrode. This is why it’s the correct designation for 1% Lanthanum Tungsten. The other options point to different alloying elements (cerium, thorium) or a generic alloy, not 1% Lanthanum Tungsten. Lanthanum-doped tungstens are known to improve arc starting and stability, which is helpful context for understanding why the designation matters.