Things You'll Need
Instructions
Clean the piece of steel you wish to blacken using some solvent-based degreasing solution. The steel must be free of any dirt, oil or other contamination before proceeding. Check for cleanliness by wetting the cleaned steel with water. If it beads off the steel, it requires more cleaning. Otherwise, proceed to Step 2.
Apply some gun bluing solution to a clean piece of cotton cloth or a toothbrush, and rub it onto the surface of the steel. The longer you apply the solution, the blacker it will become. If you have enough solution, and your piece of steel is small enough, you can submerse the steel into the solution.
Wet another piece of cloth with some new or used motor oil. When the desired blackness has been attained on the surface of the steel, rub in the oil-soaked cloth to stop the reaction.
Buff the blackened surface of your piece of steel by polishing it with a piece of 0000 steel wool. Reapply the gun bluing solution to further blacken the steel, as you wish.