Well, I can see this may get more interesting as time goes on.
John, the metal that is giving me problems is 14 g sheet copper.
Since I bought it at the scrap yard, I don’t know what kind of
copper it is. I would guess it is a cold rolled oxygen free material.
Other kinds of copper are pretty scarce. It exhibits no porosity.
After all the papers are used (600 through 4/0),
I use white diamond then red rouge. The piece is 2 x 31/2.
It is real easy to get the piece too hot to handle.
It seems to pit if I bear down on the plate
and let it heat up.
To remove the pits I’m back at the 600 paper routine again.
Have a nice weekend all.