Black T is what Walter Birdsong applies. He developed the teflon coating and it sounds like he is the man. Problem is, he can turn work away. I've left a number of messages on his answering machine....after three months, I gave up. People who had him apply it can't speak highly enough about it.
Another company does teflon coating...heard some good feedback...BLACK ICE COATING if you want to google.
Hope this helps,
Wade