When I tried the others it definitely brought out the contrast but etched the steel enough you could nearly feel the different layers of steel and softer iron. That was diluted and just a flash dip into it. I'm sure a coat of lacquer would have smoothed it out but just wouldn't have been right as well as possibly dangerous on thinner walled guns. I'm sure that with enough time etc that a strength could be formulated to work but i just gave up since the ferric did work.