Chapter Eleven 210 the MASS-PRODUCTION of STEEL

210 chapter eleven Chapter eleven The Mass-Production of Steel for Swords and Armour Bloomery Steel Making The manufacture of plate armour on an industrial scale in Northern Italy, during the late 13th and 14th centuries, was possible because iron-smelt- ing furnaces were operated in such a way (probably on the cusp of pro- ducing a liquid product) as to produce blooms large enough (10 kg or more) for making plates for armour and of a carbon content high enough (0.4% C or more) to make the armour effective. By the 15th century, the overwhelming majority of Italian armour bearing armourers’ marks was made of this steel, and much of it was hardened in some way. But these procedures were to change quite suddenly. There are three major changes in Italian armour which take place within a few years of one another around the turn of the 16th century. In the first place, and most importantly, it is almost never made of hardened steel after about 1510. Out of 84 specimens of Italian armour made after 1520 examined by this author, 41 had been made of low-carbon steel and 33 of medium- carbon steel; but none had undergone any hardening.1 This is an abrupt change in practice, and not easy to explain convincingly but it does coin- cide with the adoption of fire-gilding. This process seems to have been employed for the decoration of armour from about 1490 onwards. It rap- idly becomes very common, and increases in extent until half or more of the surface is covered by fire-gilded decoration. Evidently the heating for one operation (gilding) was found to interfere, or thought to be likely to interfere, with the heat-treatment for the other (hardening). The two operations were very seldom both carried out on an Italian armour. The second change is that the use of armourers’ marks becomes rela- tively uncommon, and effectively disappears after 1510, although some gilded armours are signed (rather than marked) later in the century. If the use of a mark was intended to be a sign of the quality of the metal 1 For the manufacture of steel suits of armour, see Williams, A. “The Knight and the Blast Furnace” (Leiden, 2003) 203–329. The Mass-Production of Steel for Swords and Armour 211 employed to make the armour, then when most customers were no longer interested in that quality, its disappearance may have followed logically. The third change is the less frequent use of steel in the early years of the 16th century, although perhaps economic factors might have been partly responsible for this. The French invasion of 1494, and the subse- quent 30 years of intermittent war, dislocated the economic life of Italy in general and Milan in particular. But there was a revival in the use of steel in the 1530s, and at the time Biringuccio was writing, the Negroli family of Milan were employing steel for their fantastic embossed armours, which allowed noblemen to pose as the demigod Hercules, Alexander the Great, or even a sea-serpent. Filippo Negroli was regarded as the finest armourer of his day, and made Milan, at least for a little while, the centre of the industry once again. More than forty specimens from more than twenty “embossed” (in fact forged) armours made by the Negroli family and their contemporaries have been examined by this author. More than half were found to be made of steel, rather than the softer iron which might have been expected, and the hardest steel pre- dominated in the best armours.2 At first sight, it may seem surprising that a material twice as hard as iron should be used for “parade” armours. But, decorative though these “parade” armours were, they were still armour. It seems clear that princes and nobles ordered their best and most expensive armours to wear as display, but with the added possibility of wearing it in battle if necessary. One Negroli helmet made for a delle Rovere was described as having been made “pistol-proof” so its owner expected to be shot at some day.3 It was not simply the invention of guns which made suits of plate armour obsolete, indeed both inventions had appeared fairly close together on the 14th century battlefield, but rather the armourers’ general response to musketry, which was to make armour steadily thicker from the last quarter of the 16th century onwards. When the metal used in the mass-produced armour of the late 16th and 17th century is examined, it is found that iron becomes commoner. It was made bulletproof simply by 2 Williams, A. “The Steel of the Negroli” Metropolitan Museum Journal, 34, (New york, 1999) 101–124. 3 Pyhrr, S.W & Godoy, J.A. “Heroic armor of the Italian Renaissance” Metropolitan Museum of Art Exhibition Catalogue, (New york, 1998) 158. Parts of this helmet are in the Wallace Collection, London, (A.207). They are 2.0 to 2.5 mm thick, and made of medium- carbon steel. .

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