Degrease and clean all parts of the steel. Also ensure you have pure steel. Any additions such as aluminum may cause the oxidation to not work properly. This method will not blacken stainless steel.
Put on gloves, goggles and heat-resistant clothing. The solution will be very hot and caustic.
Mix 1 gallon of water with 5 pounds of lye. Slowly add 2 pounds of sodium nitrate. Bring the mixture to a boil and continue to heat it until it reaches at least 290 degrees Fahrenheit.
Place the steel in the mixture, and watch as the reaction takes place. Continue to heat until it is blackened. Carefully remove the steel from the mixture using tongs.
Rinse well in warm water. Dip the steel into a shallow tub of melted water-soluble wax. Remove the steel immediately and allow the wax to cure for several hours before handling.