Hi. I have spool of #12 industrial grade tin coated copper strand
wire that I had planned on building a 40 meter vertical loop with.
While scouring the web, I came across a white paper on wire, tubing
and RF compatibility, and it said that tin-coated copper was "somewhat
inferior", but silver coated or pure copper strand were fine for
antenna use. Contrary to this, I have read in this Newsgroup that tin
or silver coating is a must-have for good RF radiation.

Any views on tin coated copper strand?

Also, where do you all find Copperweld? It sounds ideal, but I
haven't been able to find it anywhere.

Thanks!