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Introduction to the archaeometallurgy of iron

Co-fusion steelmaking in Persia

Translated from Massalski (1841, pp. 297–9); cf. Allan & Gilmour (2000, pp. 535–9).

The metals used in the preparation of Damascus steel are wrought iron, cast iron, and a small amount of silver. The former should be previously worked scrap (nils, plates, etc.), but free of rust. For the cast iron one of the best grades of white cast iron should be chosen. The silver should be extremely pure. The usual proportion is one part cast iron to three parts wrought iron by weight.

The wrought iron and cast iron are broken up into small pieces, mixed as thoroughly as possible, and charged into refractory crucibles (no. 3 in the illustration) whose height, upper diameter, and lower diameter are in the ratio 5 : 4 : 3. The size of the crucibles depends on the amount of steel to be prepared. In Persia the quantity [per crucible] is usually between ¹/₅ and 1 bacheman. (One bacheman is equivalent to . . . 2.46 kg.) The charged mixture occupies one-third of the capacity of the crucible.

The fusion furnace (nos. 4 and 5 in the illustration) is composed of a cubical brick chamber (ABCD) with flat bottom. At each corner is an opening (C) for the nozzles of the bellows. An opening is left in one wall of the box to allow the charging of additional charcoal if necessary during the operation. A false floor (mn) in the chamber has round holes with diameter equal to the diameter of the crucibles at 2/3 of their height.  . . . Usually this floor is placed at 3/4 of the height of the chamber (ABCD). The holes (o) are arranged in such a way that the crucibles are . . . 0.051 m apart. Around each of these holes are placed four small holes (q) through which the flames pass and envelope the crucibles on all sides. The furnace is closed with a cover of iron or brick, plastered with clay, which is manoeuvred with the help of a simple lever. Several holes in the cover allow the passage of air out of the furnace.

The furnace is initially loaded with sufficient charcoal to reach the bottoms of the crucibles. These are lodged in the holes (o) in the floor (mn), positioned as nearly horizontal as possible. The space between the floor (mn) and the furnace cover is completely filled with charcoal, and the cover is carefully sealed with potter’s clay. The fuel is ignited at the four corners (C), and the operation of the bellows begins. When the metal begins to melt, which occurs after 5 to 6 hours, a bubbling sound is heard which increases as the metal melts and stops when fusion is complete. As soon as the bubbling sound has stopped, the furnace cover is lifted. The crucibles are cleared of the charcoal which covers them and into each is introduced . . . 13–17 g of silver in small pieces. The contents are stirred briskly with a metal rod, the crucibles are again covered with coal, the furnace cover is replaced, all of the furnace openings are closed with clay, and the furnace is allowed to cool for about 3 days.

When the furnace has cooled completely, the crucibles are removed and the buttons [of steel] are collected. The buttons are cleaned, and any silver which may adhere to their surface is removed. In this state these are what is referred to as Damascus steel. All that remains is to test them; . . .  [A detailed description of the testing process follows.]

References