American cast items are handmade items using one of several processes and materials.
Sand casting was developed by the Egyptians and introduced to the Dine’ (Navajo)
in the 1880s. This method uses sand with a high clay content to form a mold from
a template, an existing piece of jewelry or sculpture. Two halves of a box are
filled with sand and the original piece is placed between them so the sand packs
around the template to form an impression of the original piece.The boxes are
carefully separated and the original piece is removed leaving behind an impression
of the piece. A sprue (hole into which the molten metal is poured) and air vents
are formed from the impression cavity to the edges of the mold and the two boxes
are then bound together. Molten metal is poured into the sprue to fill the mold
and allowed to cool. The box is separated and the newly cast piece is removed
and finished by grindng, filing and polishing.
casting is used by many Navajo casters today to make an original piece of jewelry
or sculpture. Using Tuff Stone, a porous rock from volcanic ash, Tufa Stone, a
porous limestone that forms near hot springs, or Sandstone, a harder stone, the
artist carves out an original design of an item to be cast, taking care to make
the edges angle outward so the metal doesn’t stick into corners when the halves
are later separated. A sprue is carved from one edge of the cavity to the edge
of the form. Another flat stone is placed against the carved half of the mold.
The halves are fastened together and molten metal is poured into the mold through
the sprue. Once the metal cools, the form is separated and the casting is taken
out and finished.
Sandcast sterling silver
like the one by Francis Begay shown here, are poured flat and then shaped.
to the porous nature of the stones, cast items will have character marks and imperfections
such as small pits. That is the nature of tufa casting and Indian Hand Made.