Chromium protects Nickel from oxidation. Oldest common chromium bath is chromic acid and sulphuric acid mix. Some chromium baths are beside our mark.(Flouride, Floborat..). We have been giving general information.
For Chromium Baths, lead is used as an anode. But it must be alloyed, not distinct. Anodes must be extracted per month, and been hanged over again. For sulphuric acidic baths %6-8 antimon must be used, for flouride baths %4-7 spelter must be used. Covered piece in cathode, takes the chromium from chromic acid. While the polyvalent chromium is coming down, in other word, adhering as chromium, on the otherside, renders polyvalent chromium to trivalent If this increases in bath, baths performance will degrade. Lead anodes mission is, transfering current electricity to electrode and also oxidizing trivalent chromium to polyvalent chromium. Our advice ; Anode/Cathode rating must be 2/1 and Anode intersections must be annular.
Because of that, washing water is very important. For old baths this pollution is indispenseble. To avoid that, rejuvenating the bath with precipitating the bath with barium carbonate, disposing the 1/3 bath water at the deep, hanging metal sheet to cathode and working with high voltage (besides, this method is used for warming the bath) are true in theory but practically FALSE.
Lead Anode must be used instead of metal sheet (in electrolyte) to avoiding the adhesion of limited chromium to metal sheet that we are going to scutch. Metal Pollution in bath abates the performance of current too. (New Chromic Acid and Sulphuric Acid must be completed for copper, zinc, nickel...2/3 and after that must be passed by the application.)
Sulphuric acid is left in small quantities while the getting chromic acid. Therefore, we increases the acid rating unintentionally when we reinforce chromium. Our advice ; to reinforce 125/250 Barium Carbonat for each barrels. 2 gram Barium Carbonat precipitates 1 gram sulphuric acid. Being more sulphuric acid or less, concludes with oxidation mistake. How do we understand that this mistake come from being more or being less sulphuric acidIf the acid is less ; chromic acid adheres to piece. And only can be removed by scouring with hand. If the acid is more, chromic acid can be removed by washing it.