Russia Sheet Iron: Charcoal-Packed Sheets Hammered to a Mirror Polish (Jordan after Koulibine, 1867)

The glossy blue-black Russia sheet iron, long a Russian secret, as the engineer Koulibine described it to Professor Jordan for the Paris Exhibition of 1867: charcoal iron is rolled into black sheets, then packed red-hot with powdered charcoal between them and hammered under a one-ton hammer, then polished cold under a second. The charcoal, shut in between the hot sheets without air, cements the surface: it takes a high polish and rusts less. Once cemented, a sheet must not go back into the heating furnace. Unknown: how the charcoal finery iron is made. The source does not give it. Source: 'Russia Sheet Iron', Scientific American Supplement No. 154 (1878), pp. 2448-2449, after Jordan's 1867 report. Picture: the article.