Can anyone tell me if there is a special type of brake pipe flaring tool / clamp available for coated pipe please ?

I have got some of the original Ford Green brake pipe for my Series 1 underbody resto, but when i clamp it in the brake pipe tool, its not gripping it properly due to the green coating on the steel pipe, and its scraping / taking off the green coating, when i push the brake flaring thread onto the end of the pipe.

Tried all sorts with no luck, i just keep knackering lengths of my nice new pipe unchballs:

Any help or pointers appreciated as i need to get the car back together asap now.

Cheers folks.

Michael