Tag Archives: bronze casting

Choosing Which Metal To Use: Part 3

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Last week we asked if there were any other issues with metal that we should consider. Well, two things come to mind immediately: metals other than bronze and lead, and knowing your metal source.

Metals were not carefully assayed in the past they way they can be today. The people who created the various pure metals and alloys were knowledgeable, and there is a considerable amount of pre-1600 written material about creating various alloys, but metal purity could not be tested with the same level of precision that we have modernly. Many alchemy texts have information on metallurgy.

When you are reading museum data base entries, the actual metal content of a piece is rarely listed. “Copper alloy” is often used to refer to any sort of bronze metal and the actually purity of precious metals is rarely noted. Until recently it has been much too expensive to test each piece to determine exactly the metal content. Larger organizations, like the British Museum, will sometimes reevaluate pieces as they clean them, and they sometimes test the metal content. Testing content has helped to reveal frauds, and modifications of artifacts, many of which were done in antiquity.

For anyone who has ever followed the types of silver that are available modernly, the two most common would be Sterling Silver (also designated as .925) and Fine Silver (.999).  Those numbers simply indicate the percentage of silver that is included in the alloy. There are other designations, including coin silver (which varies in silver content depending on the date of manufacture and the country), and Argentium Silver (which is a tarnish resistant form of Sterling Silver with special properties). The terms Bali Silver, Thai Silver, and Mexican Silver may be used in a retail setting, but have no legal meanings. Nickel Silver, or German Silver is silver colored, and does not actually contain any silver at all. It is a copper alloy.

There were an assortment of silver alloys that were used in period that are not usually used modernly. Billon has been used since at least ancient Greece. It is a silver colored alloy which usually contains silver and other metals (usually copper), and may sometimes contain mercury. It was commonly used for making coins and medals. Electrum is a naturally occurring alloy of silver and gold, which has been used since at least 3,000BC by the ancient Egyptians. It was used widely in coinage and jewelry manufacture by cultures as varied as the Egyptians and the Vikings. There are major deposits of natural electrum in Anatolia (Turkey).

All of the silver pieces that I currently make for sale in my shop is classified as Sterling Silver. My cast pieces are solid sterling, and the wire and plate that I use in my toiletry sets, needles cases and chains (both knit and link) are all solid Sterling Silver.  I do not currently work with Argentium silver. Sterling Silver alloy was used during Medieval times.

Next time: What about silver plate, silver filled, vermeil, and gold filled metals, and sources of metal?

Choosing Which Metal To Use – Part 2

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Last time we talked about choosing true bronze in order to get the look, feel, and functionality that we see in many pre-1600 pieces. But there is at least one metal that I generally avoid like the plague in my workshop – lead. Lead was widely used in many pre-1600 items (for that matter it wasn’t banned from house paint in the US until 1978). When we look at period examples of inexpensive jewelry, it is often made from lead, tin, or an alloy with lead.

This example, of a lead cross pendant from Egypt, is typical of some of the less expensive jewelry that would have been made for ordinary people.

Lead can also be used as a decorative element in jewelry, including niello and leaded enamels. Niello is a black substance that can be fused to the metal in a piece of jewelry to create a contrasting design. If you are interested in the details of how niello is made and used, please visit my blog on this topic.   The Anglo Saxon’s were masters in the use of niello. The black stripe up the middle of this Anglo-Saxon brooch is niello (and so is a lot of the tracery on the Sutton Hoo pieces).

Prior to 1990, Thompson Enamel, which produces a considerable percentage of the enamels used by both artists and industry, contained lead. Many companies still make leaded enamels. And it is safe to say that most enamels that were used before 1600’s would have contained lead. Lead makes the enamels very stable and gives them good flow properties. For more information on enamels, here is the link to one of my blogs on enamels and how they were used (I mentioned it last week, too).  And yes, I do sometimes use leaded enamels.

Lead, being a naturally heavy substance, was also used for many practical purposes like this steelyard weight.  The Bronze weight was cast as a hollow piece and then filled with lead until it was the desired weight.

Spindle whorls are another excellent example of an item was very frequently cast in lead. I own several lead spindle whorls, all of which were found in England. Lead, being a rather soft metal, is relatively easy to damage. Two of the spindle whorls in the bottom row of this picture are excellent examples of this. The far left whorl has been compressed slightly, and the spindle whorl that is the second from the right shows a significant gouge, probably from a plow.

spindles

Lead can certainly be used and worked in a safe manner, but legally there are a lot of issues. Every state has different rules about how much lead is legally permissible in jewelry, especially in jewelry that may be used by children. When I first started making jewelry I sat down to read all of the different regulations for the states that I was planning to merchant in. It didn’t take me long to decide that it was simply easier to avoid it. Whenever pewter or lead is called for in jewelry or other accessories, like spindle whorls, I simply use a good quality unleaded pewter from a reputable supplier.

Next Time: Are there any other issues with metal that should be considered?