Chris wrote:
Looking at some online TIG consumable sellers web sites it seems I can buy
TIG tungstens alloyed to make a universal electrode? I am new to TIG,
having just bought a used Migatronic MTE220. I have received red and white
banded electrodes, but I now wonder if the "grey" banded ones would allow
me to weld aluminium ally, stainless steel and mild steel without buying
several types of tungstens? I will be mainly doing light work on race car
chassis and plumbing / exhausts. Gas will be pure argon, not a mix. Thanks.

You want Zirconiated electrodes (brown color code) for aluminum. They
are astoundingly better than EWP (pure Tungsten, green color code). I
tried the EWP and the electrodes became contaminated, melted, spattered
crud all over, and made poor welds. With the EWZr electrodes, I had
vastly less trouble with contamination and started making beginner's
grade welds. I can't find any grey color code in the Lincoln GTAW
book. If your machine only does DC, you have little hope of doing
TIG on aluminum. You need AC and continuous HF to get good results on
aluminum. Pure Argon is right for Al and most other TIG applications.

Stainless can be welded with Thoriated 2% (red code) on DCEN with
pure Argon shield gas. The same electrode and gas is fine for most
other steels, as well.

If the radioactivity of the Thorium worries you, you can use Lanthanated
electrodes in most applications where Thoriated electrodes are recommended.

Jon