Sand casting is an ancient jewelry-making technique that involves using jeweler’s sand as the molding material; Delft clay, and even beach sand are used to create a mold. Sand casting allows jewelers to create castings in their own studio cost-effectively versus sending your master model to a casting house. Each piece is unique since the jeweler can only use the molds once.

Sand Casting stones are known to be tricky, and nothing is guaranteed as stones can crack or move out of place, so I went to Nadine Citerne of Nadine Suzanne Jewellery, who is the mad scientist who conducted proof testing for the Cultured Fire in Place Opals in the Sand Casting process. She creates one-of-a-kind sand cast jewelry inspired by the ocean and often has cast stones in place, making her the perfect person for testing. Nadine incorporates unique elements like beach sand, resulting in beautiful textures and organic details you will see in the successful pieces.

Sand Casting Process

1. Models Used for Casting
Common designs used can be cast rings, pendants, and bezel rings. Signet rings are also widely made using this method. A master, usually made of wood, plastic, or metal, is created. Jeweler’s wax is the typical master used as a mold alongside found objects such as shells, buttons, etc.

Nadine usually starts by carving a design in wax. The wax models are carved to allow 0.5mm space for the metal to flow behind the stone and wrap around it, securing it in place.

The wax model is then placed in a container called a flask, which is packed tightly with the jeweler’s sand to capture all the details of the master. Ring-making wax is hard, easy to carve, and does not break easily when pressed into the sand.

2. Sand Used for Testing
Nadine uses two common types of sand available on the market.
Red Clay is sand manufactured and sold by DIY Castings.
Delft Clay is commonly found in most jewelry supply stores.

3. Sand Casting Flask
A flask is an open container that holds the sand and supports the mold during the casting process. It has no top or bottom, just sides. The flask consists of two parts, called male and female. The male side has a protruding lip and vent holes.

4. Filling the Male Side of the Flask with Sand
Sand is packed into the male side of the flask from behind using a hammer, and the top is leveled off.

5. Adding the Wax Model
The wax is pressed halfway into the sand, and baby powder is brushed over this half of the mold so that the two sides do not stick together.

6. Filling the Female Side of the Flask with Sand
The female side of the flask is placed on the male side, and the sand is packed in from behind and leveled off.

7. Removing the Wax
The flask is then separated, removing the female from the male straight off without twisting. The wax model is carefully removed, leaving a cavity for the metal to flow into.

8. Sprue and Vents
Sprue and funnel are created to allow the metal to be poured into the mold. The sprue and funnel connect to the cavity created by the wax mold. This is where the molten metal will be poured into. The funnel is designed to pool any excess metal.

Vent holes are also added. These help the gas escape. When the metal is poured in, the gas needs to escape. These vent holes help the gas escape and also act as a vacuum, drawing the metal down.

9. Pouring Molten Metal
All of the rings tested were cast using a Smith Little Torch with a rosebud tip. After the mold is assembled, molten metal is poured into the gate, filling the cavity. The metal then cools and solidifies in the shape of the design, which forms the cavity.

Note: The other common type of torches used are MAPP gas bottles – these are handheld torches, but they don’t melt the silver as quickly as the Smith torch.
 

• Top Pour
  Pouring metal from the top of the flask. This method is commonly used for pendants and flat objects.

• Side Pour
  Pouring from the side of the flask, typically used for rings.

10. Removing the Casting
The metal is allowed to cool and solidify. Once the item is cast, the mold is opened right away, and the raw cast is removed and left to cool down. If the item does not have stones cast in place, it can be cooled right away in water; however, due to thermal shock to the stones, the items were left to cool on their own.
 

Casting Healing Phoenix Lapidary Cultured
Opals in Place

After creating the mold, the Opals are cleaned and placed inside the cavity. The Cultured Opals have a thin layer of pawpaw ointment (petroleum jelly) on the table of the stone to help prevent them from moving around in the mold. However, beware, when sand casting any stones in place, you are never guaranteed placement or whether the stone will survive. The ‘cast in place’ look gives a rough and organic feel to a piece.
 

• Casting Stone Placement
  All Cultured Opals have a thin layer of pawpaw ointment applied to their tables to prevent them from moving around in the mold. After casting, no rings were placed in water; they were left to cool naturally to avoid thermal shock.

• Stones that were used in Casting
  Faceted and cabochon Cultured Opals were tested. Faceted Opals size 3 - 6 mm were successful. A few cabochons did not survive; however, the 4 x 6 mm Cool Mint Cultured Opal Cabochon was shallow and survived, possibly for that reason. They are not commonly used in the sand casting or lost wax method as cabochons are more susceptible to thermal shock during casting in metal because they are not good conductors of heat and can suffer shock during rapid heat or cooling.