Van's Blue is not a coat like virtually every "cold-blue" in history. So these instructions will work ONLY for Van's, They are simple but different.
First, degrease the metal thoroughly. Then apply Van's Gun Blue with a soft-bristle TOOTHBRUSH (never a cotton swab!), and keep the metal wet by rubbing the bluing back and forth with the toothbrush over the area to be blued for 3 to 5 minutes. The longer the metal is kept wet with bluing, the darker it gets. When it is dark enough, wipe it dry with a paper towel, and within the next 10 minutes or so, wipe the blued metal down with some gun oil to neutralize the residual acid from the bluing. You are done!
Because this bluing soaks in rather than coats, it will reveal the precise texture of the metal. So to repair to perfection, smooth the damaged area to the exact shine of the rest of the gun. Whatever the metal looks like (dull, scraped, glass-beaded, shiny, etc.) it will look like after bluing. Blue as normal and you'll have a "new" gun.
To restore a firearm to look like it is in great shape for it's age rather than repaired to perfection ... The key again is the texture of the metal. After degreasing, take some #000 or #0000 steel wool, dip it into the bluing, and wash the metal with it. This will remove light to medium rust without damaging the underlying bluing. Wipe the metal dry with a paper towel. Now apply the bluing as above. The metal will all turn dark, but the shiny areas stay shiny, and the dull areas stay dull. It looks like an old gun in great shape for it's age! (This is way smarter than losing the character of the firearm by making it look new!)
We will now take each step and much more thoroughly explain it in detail to hopefully answer your questions before they happen!