Q. I recently received some old tin-plated copper to be replated. What methods can remove the old tin layer without harming the copper? S.Y.
A. The usual method for stripping tin from copper is to use a sodium hydroxide solution with a concentration of approximately 100 g/L at 75–150°F. The part to be stripped is made anodic and a steel anode is used. Voltage should be approximately 6v. If the temperature of the solution is too high, the copper base will be