Main formula of blackening agent

Copper sulfate pentahydrate (reagent) 3.0-5.0 g/L
Potassium pyrophosphate (reagent) 0.8-1.2 g/L
Nickel sulfate tetrahydrate (reagent) 0.2 g/L
Ammonium molybdate (reagent) 0.2 g/L
Alkyl phenol polyoxyethylene ether (OP-10, reagent) 0.2 g/L
Composite additive (CH2011), multiple metal salts) 0.2 g/L
Add water to 1.0L
The pH value of this solution is 2.5-3.0, the blackening time is 5-7 minutes, and the operating temperature is room temperature.