How to take off ceramic coating on a mani?

I need to remove a bit of ceramic coating on the DNP Mani so the welder can weld a bung on there. How can I remove ceramic coating around where it needs to be welded?

I talked to the welder, and he hasn't had to remove it before. He can do it, NP, but if it's labor intensive, it's going to cost me a grip. He was saying it is like glass or something, which doesn't grind off easily. He asked me what kind of ceramic it was, and I have no clue. I think Jay had it coated at PG, but I'm not sure. It's black... don't have a pic handy, but can post one when I get home.

Please let me know what is the best way to do it, or the quickest way for my welder to do it. I was going to see him tomorrow, but I'd like to get some more info, or even try to get it off myself?

TIA