GO 340 Gemstones & Gemology

Emporia State University
Susan Ward Aber

www.emporia.edu/earthsci/amber/go340/silver.htm

Working With Silver

Jewelry is a combination of gemstones and metals enhanced by hand fabrication, lost wax casting, die striking, and electroforming. Electroforming and die striking are industrial processes used with gold, platinum, and silver. Lost wax casting and hand fabrication can be done on a small or large scale, and the former will be highlighted on this page. Casting is faster than hand fabrication and repeatable.

Lost wax casting and chain making will be portrayed on this page using silver as the medium. Silver's tenacity and ready ability to melt make casting possible. These comprehensive demonstrations were given by Ernie Herrick of Emporia, Kansas. In order to learn these skills, one can complete an apprenticeship with someone such as Mr. Herrick and/or go to the William Holland School of Lapidary Arts.

The process is shown below in pictures and text but to see a video of the casting process visit Abazias Diamonds at www.abazias.com/video/engagement_ring_casting.asp. Then return and see it done on a smaller scale in the basement of a home!

Lost Wax Casting

The basic process begins with a wax model of the finished piece. Wax is easy to work with and inexpensive. Mr. Herrick explained one can purchase wax patterns or carve and create a wax pattern of your own. If more than one cast is desired from the same pattern a latex rubber mold is made. This process to replicate a ring setting is shown below.
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© by S.W. Aber


Ernie Herrick
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© by S.W. Aber 		A latex rubber is placed in this silver box container. A model of the desired finished piece, made of silver or some base metal, is packed in the center of several sheets of rubber. After the lid is screwed down in place, the rubber is squeezed and heated. The container is heated to around 300 degrees F and the rubber melds around the original design and fuses into a solid block.
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© by S.W. Aber

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© by S.W. Aber 		When the rubber has hardened, the solid block is cut in half revealing a perfect mold of the original desired design.
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Photo date 3/02; © by S.W. Aber 		This process has created a rubber mold that can be reused to make thousands of wax replicas. Warm liquid wax is repeatedly injected with a syringe through a hole cut into the rubber block. When the warm wax hardens, the wax design is created. If the design were to be mass produced, each wax model would be attached to wax trees with branches called sprues and placed in large flasks.
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Photo date 3/02; © by S.W. Aber 		To continue the transformation from wax model to metal, the design is placed inside a small flask. Mr. Herrick is cleaning and preparing the flask. He fixed the wax ring model in the flask with a small amount of play dough. A sprue and button have been attached to the wax ring.
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Photo date 3/02; © by S.W. Aber 		The flask containing the wax model will be filled with investment. The investment is a powdered substance mixed with water that is similar in consistency to liquid plaster.
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Mr. Herrick pours investment around the wax model. The material is poured slowly and tamped to guard against bubbles of air left in the flask. The investment takes about 10 minutes to harden.
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Photo date 3/02; © by S.W. Aber 		The master model, encased in the investment, is heated for several hours. The high temperature of baking causes the wax to be lost by melting and evaporation. A perfect cast of the design is preserved in the hardened investment and thus the name, lost wax casting.
After the flask has cooled, the caster will place the flask in a a casting machine or centrifuge. The casting machine would use a vacuum to draw molten metal into the mold, while the centrifuge uses centrifugal force to accomplish the same thing. Although the caster could use gold, platinum, or silver, molten silver is used in this example.
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Photo date 3/02; © by S.W. Aber 		A small casting operation, such as this example, would use the centrifuge. Silver casting grains are heated until molten and poured into the container with the investment mold. Mr. Herrick is placing the container with investment and silver into the centrifuge machine.
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Wind it up and let go! The centrifuge will force the molten silver into every part of the mold.


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© by S.W. Aber 		After the centrifuge is finished, the silver cast is allowed sufficient time to cool and harden. It is exposed by carving out the investment to reveal an exact replica of the wax original.
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photos © by S.W. Aber


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© by S.W. Aber 		The button and sprue are cut and filed off. The metal is washed and/or pickled and dried.
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Ernie Herrick
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Photo date 3/02; © by S.W. Aber 		After the setting is cast, Mr. Herrick will mount the stone. The first step is to bur a seat or open the prongs to exactly or slightly smaller diameter than the stone itself.
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© by S.W. Aber 		When the seat is right, the edges of the metal are smoothed, and the stone is ready to set. Tacking the stone is next, that is the prongs are slightly bent to hold the stone in place. Now each individual prong is pushed over the stone, around in a continuous pattern. The prongs are given a final filing and polishing...ah, the finished product!
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© by S.W. Aber

Hand Fabricating Chain

Gold chain is the most popular form of jewelry. Although chain making has been automated since the 1800s, for centuries chain was made by hand, one link at a time.
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© by S.W. Aber 		Start with precious metal wire and twist it into shape (wrap it around a dow of the proper size of link). Cut the wrapped wire and this forms individual links. Bend the links apart to join them together in different patterns to create different chain types. Attach clasp and carefully polish. See examples of silver chain Creations by Ernie on a later page or if you cannot wait, go to http://www.emporia.edu/earthsci/amber/go340/ruby.htm!

To learn more about making jewelry visit a website created by former gemstone student page:
Harris, C. (2003). Making jewelry. WWW URL http://www.emporia.edu/earthsci/amber/go340/students/harris/index.htm.

Useful sites to visit include:

Metal Testing Equipment Supplier:

Students enrolled in this course should email me first when considering any purchases (saber@emporia.edu).

Some useful books include:

Return to the Syllabus or go on to the next lecture.

This page originates from the Earth Science department for the use and benefit of students enrolled at Emporia State University. For more information contact the course instructor, S. W. Aber, e-mail: saber@emporia.edu Thanks for visiting! Webpage created: February 4, 2000; last update: 2 March 2009.

Copyright 1999-2009 Susan Ward Aber. All rights reserved.