I have used Chris Conlen of KRC Refinishing for both Manganese and Zink parkerizing. He is located in Avon. He is at the 1500 every show with a table of his work.
I'll look him up at the next show. Thanks. There use to be a table that set up about a row over from us that did it. But haven't seen them for a while. He was from Frankfort I thought.