Photo by Nikolai Sorokin, Dreamstime.com.
When it comes to
casting jewelry,
it’s all in the detail.
As Good
as Gold
Shannon Wetzel, Senior Editor
I
n the specialty niche of casting jewelry,
many manufacturers were born into
their profession, taking on perhaps a family
watch business and evolving it into jewelry
July/August 2007
casting. Others come by the profession in
a more indirect route.
Michael Binnion went to art school to study
the making of prints, pictures or designs usu-
ally printed from an engraved block. But after
graduation, the job he accepted was with a
jewelry maker, and he found himself working
with molten metal rather than ink and paper.
For Design Engineers & Purchasers
31
Worth Your Weight in Gold?
With a price per ounce of about $650, it’s easy to understand the phrase, “the gold standard.” See how other objects might
be valued if they were worth their weight in gold.
One dollar bill
Official tennis ball
Weight: 1 g
Gold worth: $191.10
Weight: 2.05 oz.
Gold worth: $1,332.50
Now, Binnion oversees production at
Sierra Pacific Casting Co., Oakland, Calif.,
which casts jewelry for the fashion industry,
jewelry designers and artisans. Although
he started with art school, Binnion’s approach to casting jewelry is decidedly
scientific—an attitude that represents the
new generation of the jewelry industry.
Photo by Maddelinemonroe, Dreamstime.com.
“I learned about jewelry making and
casting on the job,” he said. “I learned
from experienced people who’ve been
doing it for years.”
Jewelry is cast in a number of different alloys, including sterling silver (as in these charms), gold, silver, platinum, titanium and
copper-base.
32Engineered Casting Solutions
July/August 2007
Weight: 8.35 lbs.
Gold worth: $86,840
“A lot of us newer people in the trade
are bringing a scientific perspective to the
process,” he said. “The industry used to
be so secretive, but that’s not the case as
much anymore.”
Instead, many jewelry makers are
sharing their methods and outcomes
that result from new technologies. For
the past five years, Binnion has been involved in a jewelry-making symposium
that provides a forum for this type of
information sharing.
At the same time, casting labs are becoming more high tech, from prototyping
to automated finishing. Jewelry designers
are taking advantage of new tools, as well;
many send in CAD/CAM files or alreadybuilt models for new designs.
“A lot of people will give us a concept
and ask if we can make it for them, so we’ll
put together a model using CAD/CAM,”
said Geoffrey Pyle, owner of Arttech Casting, Scottsville, N.Y. “But recently, we’re
seeing more customers who have that
software and tools themselves. So they’ll
send us the actual wax model and ask us
to pour it for them.”
This more recent development is
only one of the latest in a long series of
jewelry-making evolutions that have
occurred over the last few thousands
of years. Investment casting has been
July/August 2007
Photo by Ljupco Smokovski, Dreamstime.com.
Gallon of fresh water
Peyton Manning
Weight: 230 lbs.
Gold worth: $2.39 million
there nearly every step of the way.
Ancient Beginnings
and at $650 an ounce, it is still a highly
valuable precious metal. In comparison,
silver currently runs around $14 an ounce.
Platinum’s price: $1,300 an ounce.
Small objects were first cast via the
investment casting, or lost wax, process in
Gold-Obsessed
the Near East between 3000 and 2500 B.C.
When the material you are working with
Pieces of jewelry were among the first items
is priced at hundreds
to be cast. In this
of dollars per ounce,
process, clay molds
even a speck of wastwere formed around
The key to good
ed metal is costly.
wax sculptures or
By necessity, jewelry
patterns. The molds
jewelry casting is
casters can be obseswere heated, and
sive about reclaiming
as the wax patterns
the same as for
their metal.
melted, a hollow cav“The nature of
ity in the pattern’s
any industrial
the business helps us
shape remained in
be good recyclers,”
the mold. Once the
casting—metal
Binnion said. “We
mold was cool, moland mold
collect the dust of
ten metal was poured
the metal that results
into the cavity.
temperature.
from our finishing
Since ancient
operations. We filter
times, gold has been
—Steve Brown, C.A.
the water used in
considered one of the
finishing for the remost desirable metBrown Inc.
maining particles of
als, and, along with
gold and silver.”
copper and bronze,
Sierra Pacific Casting isn’t the only reit was one of the first to be cast. Today,
cycling-savvy jewelry caster. Binnion said
the price of gold has been outpaced by
he knows one shop where the owner keeps
platinum, a newer, yet popular, material
adhesive pads by the door for employees
for jewelry. But gold’s tradition has kept
to step on before they leave. The adhesive
its position in the jewelry industry firm,
“
”
For Design Engineers & Purchasers
33
retains the precious metal dust that their
world,” he said. “Now there are fewer and
mold temperature,” Brown said.
shoes might have picked up off the floor
fewer of us left.”
Sierra Pacific Casting Co. relies on its
of the shop.
The competition doesn’t have Brown
customer service and its ability to cast
Strict attention is paid to the gating
sweating, however. Fewer domestic castdifficult shapes. “We’re a little higher
of the patterns, as well. The less metal
ers means there’s more business for those
priced, but we do trickier work,” Binnion
used in gating, the better; scrap
said. “Our customers also bring
is a four-letter word.
us their new stuff because they
“The thing about jewelry castfeel they’ll have better control
ing vs. larger investment casting
over the confidentiality of
There have always been
or even sand casting, is that what
the designs than if they went
you pour solidifies in micro-secoverseas.”
different alloys for colors. Now
onds,” Pyle said. “We have to be
Refining the casting process
there are some alloys that have
concerned with the scrap ratio
for a better product is another
and with getting the metal where
weapon in the fight against global
been developed to help with
it’s supposed to before it cools. It’s
competition. Arttech Casting
an expensive material.”
casts the typical gold, silver and
manufacturability. —Michael
platinum alloys but also offers a
More Than Metal
line of metals it calls de-ox alloys.
Binnion, Sierra Pacific Casting
Jewelry makers have another
De-ox alloys contain elements
reason to keep a tight rein on
such as boron and silicon, which
their costs. In the last decade,
help fight oxidation that can occompetition from foreign imports comthat remain. And those that remain have
cur during the melting of metal.
bined with a rising cost of doing business
figured out how to depend on their strong
“With a de-ox metal, it makes castin the U.S. has diminished the domestic
suits to continue making sales.
ing gold far more economical,” Pyle said.
jewelry industry.
“I have a niche where no one else
“We’re competing with a lot of offshore
C.A. Brown Inc. is located in Crandoes what I do,” he said. “So I’m not
companies, so we have to have these more
ston, R.I., which was once one of the
too worried.”
technical approaches.”
most vibrant and important areas of
For C.A. Brown, that niche involves takSee How They Shine
jewelry manufacturing, according to
ing on sculpture work and some industrial
Because the jewelry industry is driven
owner Steve Brown.
castings at his investment casting facility.
by the look of the object, physical charac“Rhode Island used to be the largest
“The key to good jewelry casting is the same
teristics, such as surface finish and color,
manufacturer of costume jewelry in the
as for any industrial casting—metal and
“
Photo by Michael Zysman, Dreamstime.com.
”
These navel rings are made of titanium, which has grown in popularity in recent years.
34Engineered Casting Solutions
July/August 2007
Silver Lining
Photo by Elen, Dreamstime.com.
are top priorities. “My customers require
fine detail, and they prefer not to see the
parting line,” Brown said.
Alloys are created to achieve a certain
color, rather than specific mechanical
properties. Gold, for instance, has hundreds of alloys in slight color variations,
such as green-gold or yellow-gold. While
jewelry designers concentrate on dictating
the right look for their product, it’s up to
the casters to find a way to produce the
piece. The castability of certain jewelry
metals presents a challenge.
As a newer material in the jewelry
market, titanium is difficult to cast because of the tendencies of the metal to
attract oxygen, according to Chris Jackson,
managing director of TiNomics, Ft. Myers,
Fla., a titanium casting firm. But machined
titanium jewelry pieces are not as detailed
and somewhat plain. “The casting process
is much faster, less expensive and provides
more detail and better surface finish,”
Jackson said. To counter the material’s
oxygen appetite, the metal is melted under a
vacuum, which allows the caster to control
its properties.
Currently popular white gold is another
example of a difficult material. “Gold’s not
supposed to be white,” Binnion said. “But
to make it white, nickel is added, which
makes the metal more brittle.”
The investment casting process allows jewelry casters to achieve fine detail and complex
shapes for their customers’ designs.
When an alloy is difficult to cast,
many times it is up to the jewelry caster
see as the main advantage is that [the deto use his or her experience and skill
ox] has better casting characteristics.”
to successfully produce the piece. But
Other silver alloys that have come onto
some advances have been made in metal
the scene prevent firestain, the purplish coltechnology to improve castability.
oring on silver caused by copper oxide.
Silver’s propensity to porosity is a
“There have always been different
jewelry caster’s headache. Typical scrap
alloys for colors,” Binnion said. “Now
silver must be sent to a refiner before it
there are some alloys that have been
is used again because of the porosdeveloped to help with manufacity. This is an expensive process.
turability, such as flowability and
However, the de-ox family
grain refinement.”
of silvers have improved
From Business to
c a s t a bi l i t y, a n d
Pleasure
they are more
resistant to
The actual jewelr y
surface decasting process follows
fects. Plus,
the same basic steps
they can be
followed at any other
re -me lte d
industrial investment
in-house
casting facility. Wax is
without much
injected into a mold to
risk of producing
produce patterns. These
defective castings.
patterns typically are hand“Tarnish resistance in
cleaned, and parting lines are
jewelry is a selling point,”
removed before the
gold and sterling
Pyle said. “But as a caster, Eighteen-carat
patterns are placed
silver were compound cast to form
that doesn’t really affect this bi-metal ring. The gold was onto trees. The trees
my operation other than cast first, prepped and inserted are given an investment
the wax for the casting of the
knowing it’s what my into
coating, and once that
silver component. No assembly
customers want. What I was required.
hardens, the molds are
July/August 2007
placed in ovens to burn out the wax.
Molten metal is then introduced to the
hollow molds.
Most jewelry casters will produce their
castings in some variation of this method.
Many use a vacuum-assist process for
putting the molten metal into the mold.
In this process, the trees are placed into
an enclosed chamber with an argon
or nitrogen cover gas that removes the
oxygen from the atmosphere. Once the
metal in the crucible reaches the right
temperature, it is released into the mold
within the enclosed chamber.
Some jewelry casters may use centrifugal force to flow molten metal into thinner
sections when required.
Once the metal is solidified, the pieces
are clipped off the tree. Some go through
cleaning and finishing in-house, while
others are inspected and shipped off to
the customer, who then does the cleaning. Even though the castings may be tiny,
finishing tasks can be grueling. “Just figuring out how to hold the piece is difficult,”
Binnion said.
Tumblers are used to clean the castings,
blasting them with various types of media.
The castings then are cleaned, polished and
ECS
transformed into jewelry. For Design Engineers & Purchasers
35