First, the main technical indicators PH value: 2.0-2.5 Total acid: 12-16 free acid: 4-6 Second, the standard WJ535-82 performance by the Ministry of Machinery Electronics Industry issued the "steel parts alkaline chemical oxidation technology" Third, The main step 1, the pretreatment step: (1) to the oil: Where the need blackened parts, service shall surface oil addition to the net (to oil: available degreaser degreasing metal at room temperature, can also be hot alkaline degreasing) otherwise the hair is not black, or in spots. After washing with water to the oil after the parts, and then rinse with running water. (2) Washing with water: tap water for 0.5 to 1 minute, rinse water flow of 0.5 to 1 minute. (3) to rust: Light rust of machined parts available * (proportion of industrial * and water is 1: 1) acid 2 to 5 minutes, chlorinated thick skin parts, from 1: 4 * in heating to rust. (4) water: first rinse with tap water to wash with running water float 0.5 to 1 minute. 2, black step: there will be no after cleaning grease, rust-free parts quickly immersed in black working solution, the gap from top to bottom to mention support 2 to 3 times, soaked 3-6 minutes, remove, rinse with tap water, rinse. 3, the post-treatment step: dehydration closure: would have been black and rinsed with water, drift off parts immersion dehydration anti-rust oil for 3 to 5 minutes and closed the poppet and down 3 to 5 times can be. Baptist soap: immersion in boiling 3 to 5 g liter industrial soap solution soak 1 to 3 minutes, then immersed in 20 # oil or various anti-rust oil, can improve corrosion resistance (immersion dehydration anti-rust oil, the best) Baptist sealer: high-end parts (such as photographic equipment, optical instruments, etc.) that require high abrasion resistance and gloss, available after boiling dehydration, immersion sealer. (The acrylic paint, polyurethane paint) performance indicators treated to achieve ministerial standards. 4, when the black solution maintain reduced efficacy, blue-green solution gradually receded, PH value to rise 2.5 to about 2.8 to 3.0, and a white precipitate, indicating Blackening aging, then, can be clarified by filtration, separation of the precipitate then add black liquid (PH = 0.5 ~ 5 precision measuring dipstick) PH value to be returned to the range of 2 to 2.5 can continue to use. The best use of the tank, a tank job, another tank cleanup precipitation. Specifications: 25 kg / barrel