The spray & bake that I use comes from John Norrell. I can't find his number right now, but will look this evening. It requires an airbrush, oven and squeaky clean prep work to get the desired results. Chuck is right, it will chip if knocked hard enough. If you don't build up the surface too much with a bunch of coats, you can re-touch with cold blue, or just spray & bake over the first coat. Like Chuck, I don't blue myself. I started using this product so I could offer a quicker turn around than sending out for bluing. I like hot blue better myself, but am almost as happy using Norrell's phenolic resin. I prefer to limit it's use to sights, as opposed to the whole gun.
John Harrison
Precision Gunworks
Canton GA