Some notes on gun bluing:
1. The polish, or gleam on a nicely blued firearm has nothing to do with the bluing solution or mix--and EVERYTHING to do with the preparation.
To achieve a high polish blue, you must first disassemble and clean the firearm thoroughly. Now, degrease it.
Look over the surface carefully. Note any flaws--dings, dents, etc--and remove or blend them.
Now, start with bluing stripper. All old blue or rust must be removed. After this is done, start your polish. I start with 240 grit with tight muslin wheels, and felt bobs for the small spaces. Next, 320; finishing with 400 grit. In all polishes, you must turn the work 45 degrees after polishing in one direction. Make sure that your wheels are mounted well, and trued prior to use.
After the 400 grit polish, I graduate to Brownell's 555 polishes. First, the black to get the primary finish, on a tight muslin wheel. 555 black does an excellent job of polishing aluminum, too!
Next the 555 Gray, also on a tight muslin wheel. I load the wheel for each step, and go slow with light pressure--let the wheel and the polish do the work. Too much pressure will build up heat, which leads to rounding of corners, and dishing out holes. Not good.
Finally, the 555 White--first on the tight muslin, then on a felt wheel.
I have polished guns for friends before, but only when I could get them to a bluing bath immediately. When you can do this--a mirror finished polish, no ripples or waves, all corners square and sharp, screws well appointed and no screw holes dished out--you can be assured of a premier job.
For a matte finish, you can stop after the Polish-O-Ray 320, and have the parts bead blasted with a fine mesh size. Or, use a soft wire wheel for a brushed finish. Polish-O-Ray 240 will leave a nice, matte brushed finish.
Someone mentioned oil--that is for browning. Some methods call for dunking in fish oil, some in motor oil. Both leave different shades of brown.
There is also nitre bluing, where the salts are heated, neat, to specific temperatures, and the part immersed. This is how you would achieve the "straw" coloring for Luger triggers and the like.