On the Bath Composition of Chemical Finishing

The bath composition for chemical finishing consists of metal salts, reducing agents and buffers. The correlation of these three factors and the optimum concentrations are studied. The metal salt is selected from the group consisting of nickel sulfate, nickel chloride, nickel ammonium sulfate, nickel nitrate, nickel carbonate and nickel cyanide. The reducing agent is selected from the group consisting of sodium hydrophosphate, sodium sulfite anhydrate, hy drazin chloride, hydrazin sulfate, hydroquinone and formaldehyd. The buffer is selected from the group consisting of acetic acid, propionic acid, butylic acid, vallerianic acid, lactic acid, glycolic acid, tartaric acid, citric acid and formic acid. As for the reducing agents, nothing is superior than sodium hydrophosphate. The result is as follows: 1. The optimum concentration of nickel sulfate is 50g/l. 2. The optimum concentration of sodium hydrophosphate is 8-15g/l. 3. The optimum concentration of sodium acetic acid is 10g/l. 4. The bath composition for practical operation NiSO4 30±20g/l NaH2PO2 10±5g/l CH3⋅COONa 10±3g/l 5. Thiourea is effective as brightener.