Electrolytic Removal of Enamel from Tins

I was intrigued by the Von Slatt method of enhancing Altoid & similar tins (as detailed at his Steampunk Workshop). As I have collected a number of Djarum “International” tins (due to an accursed vice), I thought they might be attractively adorned with portraits of Sts. Verne, Wells and Tesla in copperplate or etch.
While preparing the surface of the first tin for artistic process, I was amazed at how difficult it was to adequately remove the original baked on enamel design without serious damage to the metal surface beneath.
Research brought suggestions of aircraft stripper, professional services and even molten NaOH, when I chanced upon the suggestion of electrolytic cleaning. Better living through steam generated electricity!

I used TSP (tri-sodium phosphate), though sodium carbonate (washing soda) works just as well or better if you can find it, as the electrolyte (1 tablespoon in 1 quart of water), and a 5 volt/5 amp supply (with “-” connected to the tin). The “+” electrode is a small sheet of brass visible at the left of the plastic tub in the photograph below:

The enamel is released after about two hours of treatment, with almost no elbow grease required.

Even better results were obtained using a flat metal pan to both hold the electrolyte and serve as the “+” electrode. The tins are separated from the pan by a double layer of paper toweling:

This both adds safety (no accidental shorting) and reduces the distance between tins and “+” electrode pan. Process took half as long, and the enamel was released as an almost continuous sheet.