Thanks to everyone who took the time to read and post responses to my question. Many thanks.
This will give me a good starting place and sounds like good results. Thanks again.

Never encountered this before... I'm building a metal fame work out of steel for a customer. The job meets what she wants except for a few areas on the metal where I buffed a few places with a grinder.. She wants the entire metal structure to be raw metal color. (Original gray iron look.) Is there a...