That's how I'd normally apply FM solution (warmed metal, atomiser), but warming the metal before dunking in the Magic Boric seemed to cool it nicely and negate any benefit of prewarming.

FM's great stuff, but a pest to apply (well, to only the object you want coated at least). Anything smaller than a mouth atomiser invariably clogs as the solution dries on the nozzle.

I'd hazard a guess that David is either scrubbing it out with pumice or plating over it...