From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Procedure for lead plating, detailing the chemical composition and process parameters.
| Identifier | ExFiles\Box 115\2\ scan0537 | |
| Date | 14th December 1939 guessed | |
| - 2 - as that of the bearing. The anode is kept perpendicular to the surface of the solution - or wrapped in cheese cloth. The anode is discarded when it's diameter is less than ¼". Anodes are kept clean by brushing each time they are used. Current is applied immediately to each bearing as it is placed in the plating solution. The lead solution is composed as follows:- 19 oz/gal. basic lead carbonate. (technical.) 32 oz/gal. hydrofluoric acid. (50% technical.) 14 oz/gal. boric acid. (technical crystal.) .03 oz/gal. granulated glue. The hydrofluoric acid is placed in a lead lined tank with cooling coils and ventilation. The boric acid is added slowly. The basic lead carbonate, in the form of a thin water paste, is added to the acid mixture with constant stirring. The sediment in the concentrated solution is allowed to settle and the clear liquid is syphoned off into the rubber lined plating tank and the glue, previously dissolved in warm water, is added. The solution is made up to the required volume with water. During plating, that bath is kept at room temperature and agitated continuously. The solution should be filtered constantly to produce a smooth and uniform plate. .01 oz/gal. of glue is added each week - (.01 oz. of glue per gallon of solution.) Current density is 7.5 amperes per sq. ft. Time of plating is determined by trial. The specific gravity of the solution is maintained at 1.16 to 1.18. The lead content, as basic lead carbonate, is maintained at 14 to 17 oz. per gallon. The acid filtration number is maintained at 10 - 20. The Laboratory analyses the solution each week. (I'll send you the method if you want it.) | ||