Frank,

I have done heat patina on cold rolled steel for years, mostly only 24 gauge. I have found that the steel needs to have as much of the oil coating removed as possible, For pieces that are small enough, I wire brush them on a drill press with a stainless steel round wire brush. I also get better deep blue and violet colors if I heat the metal up very slowly, getting it brown first and then going into the blue and violet. It is easy to overheat the metal and go to gray. I usually get the best colors using the relatively expensive little blue bottles of propane you find in a hardware store. I don't get as good of colors with the green camp stove type propane cylinders. I haven't tried my acetylene torch. I bought a brass fitting to refill the small cylinders from a barbecue size propane cylinder and that works well.

Scrollerbear