I find no need to use AC when TIG welding silver, in fact I would
find that it comes in the way, as silver conducts heat so well that
I'm already having to turn up the amperage to fairly high levels
(compared to steel or stainless). With AC, a portion of your energy
is lost therefore I'd have to crank it up even further, thus a need
for a larger tungsten. It is similar to aluminum in that the heat
moves quickly and therefore you risk a melt out...but the oxide layer
is nothing like aluminum, it melts at nearly the same temperature.
Aluminum's oxide layer is a ceramic and will stay solid while the
underneath layer melts. With good control and the proper gas lens
you shouldn't be getting any oxides on your weld area, only hot areas
outside of your argon coverage.
Your best bet is to dump a little heat into the metal, then quickly
push the amperage up until your pool forms and move quickly across
the weld area.
I've been meaning to play around with the pulse functionality of my
TIG to see if I can get a tighter weld. Practicing with copper has
also been a good help, nearly any you find on TIG
welding copper will be useful in welding silver.
in Oakland, CA where the rains have finally come.