Solution Ammonium Citrate Potassium Acetate

Distilled water at 125F/52C, 500.0ml Ferric ammonium citrate, 8.0g Potassium ferricyanide, 8.0 g Acetic acid, 28% solution, 265.0ml Distilled water to make 1.0 liter... 

Complexing agents, which act as buffers to help control the pH and maintain control over the free metal—salt ions available to the solution and hence the ion concentration, include citric acid, sodium citrate, and sodium acetate potassium tartrate ammonium chloride. Stabilizers, which act as catalytic inhibitors that retard the spontaneous decomposition of the bath, include fluoride compounds thiourea, sodium cyanide, and urea. Stabilizers are typically not present in amounts exceeding 10 ppm. The pH of the bath is adjusted. 

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