Formula of blackening agent

Steel products are widely used in life, such as stainless steel doors and windows, as well as stainless steel dishes and washbasins. Some industries blacken the surface of stainless steel to ensure that the surface of these stainless steel products will not be corroded. Moreover, the commonly used blackening agent is non-toxic and harmless, and will not cause harm to steel or the user's body. The main formula of blackening agent is sodium hydroxide and sodium nitrite, and some chemicals such as copper sulfate, potassium nitrate and sodium citrate are added to the formula. The coordination of these chemical elements is greatly protected.