A member of the Shroud Science Group (unnamed at this time) asks:
I wish to know if there are reliable sources (especially of historical type) documenting answers to the following questions.
- Of which material was composed the Chambéry’s reliquary?
- Which was the composition of the silver alloy that probably composed the reliquary?
- Did the reliquary contained lead perhaps in the silver alloy?
I think the emphasis is on reliable sources.
This is a good question and I hope the SSG member will remember the experiment made by Dr. John Jackson together with Professor Christopher Ramsey. He could go further.
I cannot find that lead is ever alloyed with silver. Mostly it’s copper. Indeed, Wikipedia tells us that the medieval world went to considerable lengths to remove lead from silver, using cupellation. There is no mention of putting it back again.
Hugh is completely mistaken. I have the correct information, but will only reveal it ….
To who, where, when?
I do get information now and then which I am not obliged to reveal. This information can be research, papers, tips and so on and not limited to Shroud studies. It applies to most of the topics on which I write. Journalism is strongly linked to ethics.
I think that just too many amateurs are commenting and they don’t seem to respect the professionals. Is that how “Shroudies” want to convince Turin?
Really? This link suggests that Hugh is spot on.
Copper is the most likely metal to have been used, certainly in history, to reduce the high melting point (960C) of silver, and to make for a tougher more hard-wearing end-product.
It’s highly unlikely that the reliquary housing the Chambery shroud would have dripped molten silver onto the linen in the 1532 fire if it had been pure silver. It requires a roaring blue bunsen flame to melt pure silver – not the sort of orange-yellow flame one gets from burning timber, especially if the oxygen supply is limited. Thus the notion that it must have been a silver alloy, probably silver/copper.
Hugh is, of course, entirely correct.
Hugh does not say that a silver/lead alloy is impossible, nor that such an alloy is wholly unknown, nor that no lead has been found on the Shroud. He suggests silver is not generally alloyed with silver, nor ever has been, which I challenge Louis to refute, if he thinks I am mistaken. If, in fact, there is a secret alloy known only to a few cognoscenti, including Louis, of course, about which, of course, he is sworn to secrecy, then I do not think my opinion has been discredited.
I do not believe that the damage to the Shroud was the result of the fire in Chambery chapel…
And some Bhutanese coins are made from a silver/lead alloy, so maybe the Shroud is Himalayan…
I mean, “He suggests silver is not generally alloyed with lead, nor ever has been”.
Hugh says “Louis, of course, about which, of course, he is sworn to secrecy”.
Nobody has sworn me to secrecy it is a question of ethics as I commented previously.
If Hugh does not understand that then there is nothing more I can say.
I will maintain my silence till I have more concrete information from various sources and it must be remembered that we are talking about hypotheses. The Chambery chapel fire is just one of them and the experiment made by Drs. Jackson and Ramsey had no success. That does not mean that other attempts cannot be made, with results a long distance from what Hugh is thinking.
It seems that Lead may be used in silver-smithy work, not usually as part of the main alloy, but occasionally for some solders and also as an aid in decorative work.
The Wikipedia article on Alloys identifies no silver-lead alloy, and most solders for silver seem to be an alloy of tin and silver.
“In silversmithing or jewelry making, special hard solders are used that will pass assay. They contain a high proportion of the metal being soldered and lead is not used in these alloys. These solders vary in hardness, designated as “enameling”, “hard”, “medium” and “easy”. Enameling solder has a high melting point, close to that of the material itself, to prevent the joint desoldering during firing in the enameling process. ”
From a very comprehensive Ency Brit article on “Metalworking”: —
From Inlaying: … …
“Niello is the process of inlaying engraved ornamental designs with niello, a silver sulfide or mixture of sulfides. The first authors to write on the preparation of niello and its application to silver were Eraclius and Theophilus, in or about the 12th century, and Benvenuto Cellini, during the 16th. According to each of these authors, niello is made by fusing together silver, copper, and lead and then mixing the molten alloy with sulfur. The black product (a mixture of the sulfides of silver, copper, and lead) is powdered; and after the engraved metal, usually silver, has been moistened with a flux (a substance used to promote fusion), some of the powder is spread on it and the metal strongly heated; the niello melts and runs into the engraved channels. The excess niello is removed by scraping until the filled channels are visible, and finally the surface is polished.”
From section on Lead:
” … In the 12th century the German monk Theophilus, in his treatise on metalworking, refers to lead only in connection with casting rods for stained-glass windows and as a material through which silver sheets might be hammered; … Lead could even be useful, in the proper disguise, to simulate rich ecclesiastical objects, for not all religious institutions were wealthy: a group of 14th-century caskets covered with lead tracery, gilded to look like precious metal, have survived in church treasuries. These were used as reliquaries, but some were originally made for secular purposes.”
“The Renaissance passion for collecting bronze medals and plaquettes led to a demand for cheap replicas, and these were made with great precision in lead. The metal also played an important role in the goldsmiths’ trade. The fashion for elaborate relief ornament of the Renaissance and Mannerist periods called for a degree of skill in modelling that was beyond the powers of the average goldsmith. The practice therefore grew up for the pattern makers of Augsburg and Nürnberg, Germany, to sell lead models of ornamental details and figures from which goldsmiths working elsewhere could in turn make molds.”
So fundamentally, it would be good to know something about the casket commissioned by Margaret of Austria in 1509. Where was it made? Who made it? How was it made? What did it look like? What was its shape and how large was it?
Was it made from silver sheets fastened together, perhaps by rivets or soldering? Or else from a single sheet hammered into shape and sealed with soldering? Or was it cast as one piece by say the lost-wax method? What ornamentation did it have? Could this have included niello work, or something similar? Could lead models have been used for the purpose of ornamental molds?
In brief, it is unlikely that lead was alloyed with the parent silver for the casket, and doubtful that it would be used for any soldering purposes if made from sheets. However lead might have been present, either as minor contamination from the methods used, or else significantly present in any niello-like work, or other similar ornamentation.
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