Period Solder

I could (and will) write an entire paper on this subject. Period silver alloy solder is a mix of silver and copper. (Gold solder is either gold and silver, or gold, silver, and copper.) The fascinating thing about solder is that the melting point of the alloy is lower than the melting point of either of the component metals. For my alloy, I used two parts silver to one part copper, which comes from Theophilus. According to modern sources, alloy solder existed prior to the 12th century. Higgins, in Greek and Roman Jewelry, says that it dates back to the 3rd millennium BC in Mesopotamia. However, we don't have the information about what alloy was being used. Pliny mentions using lead to solder silver, but that's a nonstarter for recreation. That would be considered a "soft" solder, and Higgins distinctly says that hard soldering was known and used. He further says that lead was used to solder silver plate, specifically. Pliny does not mention soldering silver for jewelry specifically. He more talks about it related to statues (probable statuettes) and decorating furniture and larger objects. 

Let me digress here to say that there is extant silver jewelry from Rome. It's not the delicate filigree and wire work that I do, it tends toward chunkier pieces like snake bracelets. There are also "copper alloy" brooches that I would bet money have silver content. The brooches tend to be decorated with chemplevé, which is a form of enamel where the pattern is carved in, rather than built up, as in cloisonné. Despite a severe lack of silver jewelry in delicate styles being found, Higgins posits that more silver jewelry styles are possible and even likely to have existed. There are two issues that I see, one of which is that silver oxidizes. Higgins calls it perishable. The other issue that I posit is that at times, it may have been sacrificed to coinage. It is not unknown for jewelry to have been made from coins, and the reverse is equally plausible. 

Anyway, back to solder. I finally got around to making my own! I did not use the crucible in the photo. I used Cathyn's glazed crucible. I used a modern torch and a graphite rod for stirring. I used tiny graphite molds because my intention is to share. I used an ounce of silver and half an ounce of copper, so it made plenty. Cathyn got a little bar, and I intend to give some to my friend Susanna, as well. Some of it will get filed into powder. Some of it may get hammered into sheet, but the pieces are small enough that that might also not happen. If I can borrow the use of a rolling mill, I will. In hindsight, I perhaps should have used the bigger mold and cut pieces off.

Watching the process of melting was interesting. Even with an acetylene torch, it took a while for the silver to melt. By comparison, it took almost no time for the copper. I was seeing the science in action! The alloy melting temp is lower than the melting temp of either individual metal, so as it came into contact, the copper melted instantly. Cathyn helped by heating the molds while I melted the metal. In a forge, it would be easier to have heat on both simultaneously. We were in a jewelry shop that thankfully had two torches.

The metal poured nicely even though I was shaking badly. Have I ever mentioned that I'm actually afraid of fire? I am. We did pickle the pieces as there was some oxidation on the top. Pickle was absolutely not known in Rome. To that end I also mechanically removed some of the oxidation from one piece. The resulting alloy is still a lovely silver color. 

Next steps: filing and hammering/rolling.

The setup.

The product.