Recent research indicates that most of Giambologna’s small bronzes tested so far are leaded bronzes. (Information provided by V&A Sculpture Department.) At the time the monkeys were cast Giambologna did not have his own foundry and there is documentary evidence that he used the metal of guns captured by grand ducal forces and kept in guarded places like the Fortezza da Basso, Florence (30).

The fact that the metal is thought to be German or North West European does not prevent the monkeys from being made in Italy, nor does it mean the monkeys have to be made in Germany. The quality would seem to indicate that they are not aftercasts. There is nothing to suggest that the monkeys are copies. It is well documented that the Italians were importing copper from the Tyrol, Hungary, Thuringia, Neusohl, (present day Banska Bystrica in Slovakia). According to Biringuccio (De La Pirotechnia, Venice, 1540) the Italians had little or no copper of their own. (Information kindly supplied by the V&A Sculpture Department.) The famous Fugger banking family played a prominent role in the exploitation and export of copper.

Sculptors in bronze often sought advice from expert gun founders on where to obtain copper, also on the quality and price. The equestrian figure of Ferdinando I by Giambologna and Pietro Tacca was made of the metal of captured Turkish guns (31). Turkey was known to import copper from South Germany across the Mediterranean in Venetian ships) (32) and the equestrian figure of Cosimo I also by Giambologna was probably made of Hungarian copper.

One of the finest representations of Florentine metal work is to be found in the doors of the Baptistery, the famous Gates of Paradise by Ghiberti (completed 1450) yet the metal is not Italian but was imported via Bruges and its purchase is well documented (33). Attributions to country of manufacture cannot be deduced by the origin of the metal. Particularly when there was such a large export trade.

Giambologna is known to have used gun metal and the background to this is important. Italy in the first 60 years of the 16^th century was a war zone. Vast amounts of ordnance were brought in starting with Charles VIII’s French invasion in 1494. Long standing dynastic claims was the usual excuse (if excuse be needed) for all the many invasions but campaigning was the sport of Kings, they enjoyed it. King Charles brought with him more guns than had ever been seen together in Italy before. As a rule bronze guns when damaged or worn out could only be broken up and recycled and the use of bronze was preferred over iron because bronze was a less dangerous material and split rather than shattered. We can conclude there was copper alloy available in large quantities from broken or worn out guns.

Cannon entering Italy came from all over Europe and it is reasonable to assume the constituents varied. In 1550 there were gun foundries in England, Sweden, Northern Germany, Low Countries, France, Spain, Portugal, Poland, Eastern Adriatic, etc. If the foundry used by Giambologna used recycled gun metal with the guns coming from different foundries and likely to vary in their constituents then it seriously complicates attributions based on the make-up of the metal. Quite obviously the use of gun metal makes statistical analyses useful but hard and fast conclusions of limited value. Giambologna accepted the metal provided by patrons of which he could scarce know the constituents (including gun metals) and much of his work was done by outside foundries. Thus it is debatable how much control he had over the metal used in his bronzes. It complicates the picture. The quality of an item under debate is possibly the best guide.

The metal comprises 13 different elements, predominantly copper of course, but also including gold and silver. Copper can contain gold and silver and this is a pointer that the metal could be old. (34)

It seems that most Giambologna small bronzes tested so far have been leaded bronzes. The addition of high levels of lead would probably be intentional to take advantage of the properties of lead to lower the melting point of the alloy (m.p. of lead is 327.4°c) and to improve the flowing properties so as to help fill the mould. Lead gives a duller colour to the alloy and makes easier the work of chiselling and planishing during the finishing process. The isotopic composition of lead in copper alloys may give clues as to origin. The scientists hold out possibilities of further information. (35) The addition of lead and zinc not only lowers the melting point, but reduces the shrinkage of cast bronze.

Gun metal was usually 90% copper, 10% tin, but some foundries added latten, a mixture of copper, zinc and lead, to give a better colour. As the monkeys are a gun metal and an attractive red-brown colour this might account for the zinc content. In the 1550 edition of Vasari’s Lives it is stated that for bronze statuary the proportion of metal was two thirds copper to one of brass (brass is an alloy of copper and zinc). The zinc content of the monkeys is 5.63% and 5.88% but zinc seems to be a fugitive element, tending to evaporate rapidly in some quantity and oxidate if the fusion is not done correctly. There has to be a reducing atmosphere. After all the melting point of zinc is 418 degrees centigrade and the melting point of copper is 1083 degrees centigrade. The element zinc itself was not isolated as a pure metal until the mid 18^th century. (36)

The scientists hold out possibilities that the patterns of trace elements in metal alloys can provide finger prints capable of distinguishing artefacts made in one region from those made in another but the use of gun metal by Giambologna will obviously be a complicating factor.

For the monkeys to be of a 16^th century date and to enable repeat casts to be made they would normally be cast by the lost wax process using re-usable piece moulds and not the lost wax process where the original model is lost. Most of the evidence of the use of piece moulds has been removed but traces of the seams remain especially on the base. (38)

X-radiographs taken by Dr Brian Gilmour at HM Armouries, Tower of London, reveal evidence of numerous discs, probably the cut-off runners and risers (sprues). Also "plugged" square holes from the use of square core pins or chaplets, which hold the core in place when the wax is melted out are present. They also reveal patched casting flaws and a wire armature in the tail of one monkey. Giambologna is known to have used wire armatures to give support to the structure of the core and they also acted as core pins. Sometimes short pieces of wire were used to strengthen isolated sections of the core. The trace elements of iron may have come from these wire armatures.