Sure, I guess I missed that part.
First I remove the dross from the back side with a 4.5" compatible wire wheel on a grinder, but I do not touch the top side. It is too aggressive and can be hard to get the scratches out later. Then I use a degreaser or mineral spirits to clean the oil off of the part, as well as any metal dust/debris from cutting. Once the part is at the stage, I'll switch to a 2" die grinder with a scotchbrite roloc pad. I prefer the red one (medium grit) as a general starting point, but will switch to the green one if I want the finish to be brighter. You could use 600+ grit and get it super polished and I'm sure it would look even better. Not something I have tried, but it would be nice looking I'm sure.
Keeping the angle of attack consistent and grinding in the same direction, I'll polish up the entire surface. Once this has been completed, I'll go back and add swirls if wanted. The cleaner and more brightly polished the surface, the better with these patinas.
With hot rolled, I do the same thing but remove the mill scale with muriatic acid (HCl) or sand blast it first, but it is a bit more work and the CR sheets are only a few dollars more for me.
