Zirconium Tungsten electrodes have a beautiful round shaped end during welding and have less risc to drop off into the weld compared with pure Tungsten. This electrode has also less tendency to rectify the AC current than a pure Tungsten electrode. This means you have to set another balance point on your machine.

Zirconium Tungsten is more expensive, but easier to weld with.

well here is a strange but but good way of welding aluminum, I use a 2% thoriated tungsten to weld it due to the fact that it keeps its point better.

set the ac ballence to full pen or 100 percent if aluminum is acid cleaned and wiped with alcohol or acitone and i use a sharp 3/32- 2% thor tung and weld with .035 filler or .065. key is weld prep if your alum is oxidized or dirty you will have massive perosity and poor cosmetic appearance. do not touch weld area with bare hands use O.J. simpson rubber cloves or sergical cloves wile handling material. while welding be sure to apply filler so that it completly melts into the weld pool. this procedure will give you less perosity along the toe of the weld and it should be a shiny look to it. you should have 100 percent penatration without any unmelted wire sticking thrue but have a nice even flow of penatration[ or burnthrue ] the ac ballence is intended to HELP clean the aluminum, but is not a cleaning agent , use a gray wheel or scothbrite but best results is stainless steal wool with acitone, try it the aerospace industry loves it and so do I. AWS Mill spec 1595-A [Weld Specialties] weldspecialties@msn.com