Cast Silver Jewelry: How to Read It

Part of the Southwest Buyer's Guide.

A cast piece starts as molten silver poured into a mold. The mold can be carved stone, packed sand, or a wax model buried in plaster and burned away. Each method leaves its own marks, and each one answers the question "is this one of a kind?" differently. This page shows how to read a cast piece and what to ask the person selling it.

• Carved-stone cast. Poured into a mold carved from tufa or sandstone. The back is often grainy or pitted, then filed.
• Sand cast. Poured into a mold of packed sand. The back is flat and may show small dents.
• Lost-wax cast. A wax model is buried in plaster and melted away. One piece, or many if a rubber mold is made.

The tell: the back of a piece is a clue to the method. Only the maker can tell you how many pieces came from the mold.

Carved stone: tufa and sandstone

This is the cast most people picture. A design is carved into a flat block of stone, a second block is fastened against it, and silver is poured in through a channel. Lois Essary Jacka describes it: "A design, along with air vents and a channel, is carved into a flat piece of tufa-stone, another is clamped tightly to it, and molten metal is poured through the open channel into the carved design. When it cools, the piece is removed from the mold, then cleaned, filed, ground, and polished to completion" (Jacka 1995, p. 55).

The stone itself goes by two names. John Adair calls it "tuff, a volcanic ash similar to pumice" (Adair 1944, p. 63), and Mark Bahti's glossary calls tuff "a volcanic rock carved out for sand-cast work, often mistakenly called 'tufa'" (Bahti 2007, p. 210). In the trade it is tufa. Geologists call it tuff. Neither word is wrong on a tag.

The word "sandcast" causes more trouble. Many sellers use it for this carved-stone method. Jacka calls the carved-stone technique "Often erroneously referred to as sandcast" (Jacka 1995, p. 55), and Larry Frank's glossary suggests where the name came from: "This term may have resulted from the early use of sandstone for molds" (Frank 1990, p. 204). So when a tag says sandcast, ask what the mold was made of.

Navajo smiths took up casting from Mexican metalworkers. Grey Moustache, a Navajo smith, told Adair: "Many years ago the Navajo used to make lots of cast silver. We learned how to do this from the Mexicans" (Adair 1944, p. 8). He added that the first Navajo molds were hard rock, and that he first came across the soft, powdery stone used later on a trip to Sunrise Springs about forty years before he spoke, around 1898 (Adair 1944, pp. 8–9). Cast bracelets "date back to about 1875," the age of the oldest cast bracelets in the Laboratory of Anthropology's collection (Adair 1944, p. 39). It is a technique Navajo smiths made their own. Jacka, writing in 1995, called it "still preferred by most Navajo jewelers who cast their work" (Jacka 1995, p. 55).

For a smith's own account of the difference between sandstone and tufa, see Two Types of Navajo Silver Cast Work, in which the Navajo silversmith George Francis explains his molds.

Packed sand

True sand casting packs damp sand around a shape instead of carving stone. Paula Baxter describes it: "Smiths also learned to sandcast by pouring the molten metal into a vessel filled with firmly packed sand that had been shaped into the desired design; this technique is still used by some native jewelers." She adds what to look for: "The back of a sandcast piece is flat, but it may show small dents from the removal process" (Baxter 2000, p. 29).

Because the shape comes from a pattern rather than a carving, a sand mold can be made again. Theda Bassman's glossary puts it plainly: "A prototype mold is designed so that many pieces of jewelry may be produced" (Bassman 1997, p. 76).

Lost wax and spin casting

In lost-wax casting, the smith makes a model in wax, buries it in plaster, and heats it until the wax melts out, leaving a hollow the silver fills. The method itself is very old. Baxter notes that it "was practiced in ancient Egypt." But, she adds, "it is a technique that came late (mid-twentieth century) to native jewelers, who had relied more on sandcasting and tufa casting" (Baxter 2000, p. 102).

Lost wax can make one piece or many. It depends on what happens to the model. Once a rubber mold is taken from it, Jacka explains, "both the rubber mold and the original master may be used again" (Jacka 1995, p. 53). Writing in 1976, Marsha Lund took up spin (centrifugal) casting, which had caused "a fiery controversy." Spinning the metal into the mold doesn't by itself mean mass production, she argued, since it "is being used by some Indian artists to make one unique piece" (Lund 1976, p. 129). The problem, she wrote, lies elsewhere: "The dirty words in this process should be Rubber Molds, not centrifugal casting" (Lund 1976, p. 130).

Lost wax is also how many fine-art jewelers work. Baxter: "many fine-art jewelers use lost-wax casting methods to create nontraditional forms" (Baxter 2000, p. 29). A lost-wax piece isn't a lesser piece. It is a different method, and it should be named as one. Our own Craft & Cast workshop uses lost wax. It is a studio method, not tufa or sand casting.

Is it one of a kind?

"Cast" alone doesn't answer this. The mold does. Our reference books give a range:

• Once. Margery Bedinger: cast pieces "are often one of a kind, because frequently the mold can be used but once" (Bedinger 1973, p. 33). The Navajo jeweler Ric Charlie, on his own stone molds: "The mold is ruined when I pull out the finished piece, so a new one has to be carved each time" (Jacka 1995, p. 55). Theda Bassman's glossary entry for tufa casting ends the same way: "Usually only one piece of jewelry is achieved per cast, and then the mold is destroyed" (Bassman 1997, p. 76).
• A handful. William and Sarah Turnbaugh, on one tufa mold: "On average, no more than five or six castings may be made before this type of tufa block wears out" (Turnbaugh 2007, p. 44). Adair found that a tuff mold "will crack after less than a dozen pourings" (Adair 1944, p. 150).
• Indefinitely. The same page of Adair: a mold carved from hard rock, once made, "will last indefinitely" (Adair 1944, p. 150).

Undercuts are often the reason. Ric Charlie: "When I carve the stone, I undercut the design. Silver shrinks as it hardens, and it grabs onto everything" (Jacka 1995, p. 55). So the honest answer to "is it one of a kind?" comes from the maker, not from the word "cast." Some tufa casters sell the carved block with the piece. See Ask for the Rock, on the Navajo tufa caster Aaron Anderson.

Reading a cast piece

• Turn it over. The Turnbaughs: "Hand cast silver usually has a distinctive grainy texture to the reverse." Their photo of a cast brooch notes that the back "is pitted with tiny holes which have been partly smoothed off by filing," while "the backs of machine-made or spin-cast examples can be distinguished from this traditional hand cast work by flow lines or streaky marks acquired during the spin cast cooling process" (Turnbaugh 2007, p. 35).
• Look at the form. On early cast bracelets, Adair saw the surface "broken up into curvilinear bars separated by spaces," with sides that "are not straight" (Adair 1944, p. 39). A wrought bracelet is a solid band.
• Look for exact twins. Lund: "If you ever do see more than one piece of jewelry exactly alike, however, that will tell you that they have been mass-produced" (Lund 1976, p. 130).

⚠ A grainy back is evidence, not proof. Lund warned in 1976 that a mold of cement and motor oil leaves "the same tiny perforations that it would have if it had been sandcast or tufa cast" (Lund 1976, p. 131). Ask about the method as well as looking.

Is cast work handmade?

It can be. The FTC's jewelry guides don't rule a technique in or out. They ask how the work was controlled. A product may be called handmade only if "the entire shaping and forming of such product from raw materials and its finishing and decoration were accomplished by hand labor and manually-controlled methods which permit the maker to control and vary the construction, shape, design, and finish of each part of each individual product" (16 CFR § 23.2(a)).

The Indian Arts and Crafts Board's 1937 standards drew the line in the same place. They allowed cast work: "Unless cast, the slug or other object is to be hand hammered to thickness and shape desired" (Indian Arts and Crafts Board standards, 1937, reprinted in Wright 2003, p. 130). For the full distinction, see Handmade vs. Handcrafted.

Casting at a glance

Method	The mold	The back of the piece	How many from one mold
Carved stone (tufa, sandstone)	Design carved into stone, a second block fastened on	Grainy or pitted, often filed	From one to a handful in tufa. Hard rock lasts longer.
Packed sand	Damp sand packed around a shape	Flat, may show small dents	Repeatable from the pattern
Lost wax	Wax model invested in plaster, melted out	Ask the maker	One, or many if a rubber mold is made
Spin cast from rubber molds	Rubber mold of a model, filled by centrifuge	Can show flow lines or streaks	As many as the maker wants

Secret Questions

From our pocket guide:

• What casting method was used to make this piece?
• Does the maker control their casting process in-house?
• Can the seller describe how the mold was created?

Sources

John Adair, The Navajo and Pueblo Silversmiths, University of Oklahoma Press, 1944, pp. 8–9, 39, 63, 150. Lois Essary Jacka, Navajo Jewelry: A Legacy of Silver and Stone, Northland Publishing, 1995, pp. 53, 55. Mark Bahti, Silver + Stone: Profiles of American Indian Jewelers, Rio Nuevo, 2007, p. 210. Larry Frank, with the assistance of Millard J. Holbrook II, Indian Silver Jewelry of the Southwest, 1868–1930, Schiffer Publishing, 1990 (first published 1978), p. 204. Paula A. Baxter, with Allison Bird-Romero, Encyclopedia of Native American Jewelry, Oryx Press, 2000, pp. 29, 102. Theda Bassman, The Beauty of Navajo Jewelry, Kiva Publishing, 1997, p. 76. Marsha Mayer Lund, Indian Jewelry: Fact and Fantasy, Paladin Press, 1976, pp. 129, 130, 131. Margery Bedinger, Indian Silver: Navajo and Pueblo Jewelers, University of New Mexico Press, 1973, p. 33. William A. Turnbaugh and Sarah Peabody Turnbaugh, Indian Jewelry of the American Southwest, Schiffer Publishing, 2007 (first published 1988), pp. 35, 44. Margaret Nickelson Wright, Hopi Silver: The History and Hallmarks of Hopi Silversmithing, revised edition, University of New Mexico Press, 2003, p. 130. U.S. Federal Trade Commission, Guides for the Jewelry, Precious Metals, and Pewter Industries, 16 CFR § 23.2. T.Skies Southwest Buyer's Guide pocket guide.