Shibuichi is a low-silver alloy that's getting some buzz in the metalsmithing community. As you might guess from the name, it is a Japanese term. It translates to "one fourth",which is a reference to the traditional shibuichi alloy mixture that historically has been composed of 25% silver and 75% copper. Back in the days of the Samurai, Shibuichi was used to make ornaments for the katana (Samurai sword).
So why are metalsmiths exploring this ancient alloy? When the price of silver is up, working in Shibuichi is a great way to reuse scrap, and by mixing the silver with copper, it becomes an affordable alternative alloy to consider.
In fact, many metalsmiths are using alternative ratios of silver to copper. Mixtures of 5% silver/95% copper and 15% silver/85% copper are both commonly used. We also know of at least one jeweler who uses a rich 35% silver/65% copper alloy. As you add more silver, the metal will become more stiff, so for a softer alloy stay with the 5% or 15% formulation. For a bit of spring, go for the 25% mixture, and to really stiffen it up move up to the 35% mixture.
All of these formulations are both tough and hard, and another great thing about Shibuichi is how well it takes color from patinas. In general, the more copper in the mixture, the more colorable they are.
Interested in experimenting with Shibuichi, but aren't ready to make your own? Rio Grande now offers handmade Shibuichi sheet as well as mokume gane sheet and rod that incorporate Shibuichi.