Which option correctly identifies the TIG arc starting method?

• A. Scratch start
• B. Low-frequency start
• C. High frequency start
• D. Bridge start

Answer: (C)

High-frequency initiating the TIG arc is the method that lets you start the arc cleanly without touching the tungsten to the workpiece. The HF signal at the torch ionizes the shielding gas and creates a plasma bridge, so the arc can form at a small gap between the tungsten and the metal. This minimizes contamination of the tungsten tip and the weld, gives an immediate, stable arc, and is especially advantageous on thin or delicate materials.

Scratch start, by contrast, requires dragging the tungsten across the workpiece to start the arc, which can gouge the surface, contaminate the tungsten, and lead to a less controllable start. The terms low-frequency start and bridge start aren’t the standard, reliable methods for initiating a TIG arc, whereas high-frequency start is specifically designed to establish the arc quickly and cleanly at a distance.