What's the best way to mask threads for powder coating?

I thought about masking tape, but is this going to burn or turn into a gooey mess when the parts are heated to melt the powder?

there is a proper high melt point tape for the job
http://www.mocap.co.uk/polyester-polyimide-tape.asp

you may be able to blag some from the guys who are coating your parts

Normally the people doing the powder coating do the masking - they have the correct kit. High-temp tape for external threads and big holes, and nylon bungs for internally threaded holes.

In my distant days of motory bike powder coating, the threaded holes were bunged up with little rolls of cardboard and external threads were covered in ally tape.

[Edited on 10/6/08 by owelly]

Thanks chaps - I knew there would be a "correct" way to do it