Califbill wrote:

wrote in message
...

On Apr 22, 10:51 pm, "Califbill" wrote:
What is a good backing plate to
prevent a big gob of aluminum slump on the backside, where I can not get
the
grinder after I use the spool gun on the top. If I had a TIG outfit,
might
be easier, but only a spool gun. 1/4" steel plate? Stainless plate?

I like copper.

Dan

Reply:
I thought about that, but since this is 50xx aluminum for corrosion
protection, I was thinking that would add copper to the weld.

I recall Ernie noting not to use copper to back aluminum for that
reason.