Just got this message from a fellow artillerist in the UK about "clear-color" -
Quote - "
What they do is clean it an then use a chemical process, they can use zinc and clear, which is what you see on new car brake servos, they can do it in almost any colour, the black looks nice, it can even be done as a clear,which leaves the surface shiny, its not a paint its a chemical process, zinc and clear or passivate is what they use on nuts and bolts etc, makes them look nice and protects them, one of the treatments they do is japanning, a black chemical etch, I had a small barrell done in zinc and clear looks like new matt chrome, and its hard as hell."
Does this sound like any of the processes you have in the states ?