Black oxide is a finish produced over metal using an oxidising process. Finishing a product is done for its aesthetic appeal, as well as to protect the metal from corrosion. There are two ways to create a black oxide finish: hot and room temperature. The hot black oxide method requires the mixture to be heated to 272 to 285F, whereas the room temperature method does not. When finishing metals at home, it is safer to use the room temperature method.
Clean and degrease your tools. Use a wool scrubber to remove rust and dirt, and a degreasing agent to remove oils.
Prepare the oxide mix in a bucket according to the directions. Directions vary, so pay close attention to the water-to-oxide ratio.
Attach your hooked wire to a tool and immerse it in the mix. Remove it after it has reached a desired shade of black.
Dry off the tool with a soft cloth. If at this point you notice an uncovered spot, dip the tool in the oxide mixture again, and then dry it off.
Dip the tool into the kit's penetrating sealant. This process takes anywhere from 5 to 10 minutes. Remove it from the sealant when ready.
Allow to dry overnight.
Black oxide kits vary, so make sure that your metal is on the list of those that can be finished with your kit. There may be an oily feeling to the finish even after it is dry. This will go away within a few weeks.