When cleaning contaminated tungsten, do NOT break off the end of the tungsten.
Breaking tungsten can cause splinter fractures, resulting in erratic arc. Use a cutoff wheel or the edge of a grinding wheel.
At Arc-Zone we would add the recommendation that you use a dedicated diamond wheel for grinding to avoid contaminating your tungsten.
Download your free guide to Selecting Tungsten Electrodes (.pdf) and Grinding Tungsten Electrodes (.pdf) — available in the Arc-Zone Welding Library.