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Metal clay is a
crafting medium consisting of very small particles of metal such as
silver
Silver is a chemical element with the symbol Ag (from the Latin ', derived from the Proto-Indo-European ''h₂erǵ'': "shiny" or "white") and atomic number 47. A soft, white, lustrous transition metal, it exhibits the highest electrical ...
,
gold
Gold is a chemical element with the symbol Au (from la, aurum) and atomic number 79. This makes it one of the higher atomic number elements that occur naturally. It is a bright, slightly orange-yellow, dense, soft, malleable, and ductile ...
, bronze, or
copper
Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pink ...
mixed with an
organic binder and water for use in making
jewelry
Jewellery ( UK) or jewelry ( U.S.) consists of decorative items worn for personal adornment, such as brooches, rings, necklaces, earrings, pendants, bracelets, and cufflinks. Jewellery may be attached to the body or the clothes. From a w ...
,
bead
A bead is a small, decorative object that is formed in a variety of shapes and sizes of a material such as stone, bone, shell, glass, plastic, wood, or pearl and with a small hole for threading or stringing. Beads range in size from under ...
s and small sculptures. Originating in Japan in 1990, metal clay can be shaped just like any
soft clay, by hand or using molds. After drying, the clay can be fired in a variety of ways such as in a
kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
, with a handheld gas torch, or on a gas stove, depending on the type of clay and the metal in it. The binder burns away, leaving the pure
sintered
Clinker nodules produced by sintering
Sintering or frittage is the process of compacting and forming a solid mass of material by pressure or heat without melting it to the point of liquefaction.
Sintering happens as part of a manufacturing ...
metal. Shrinkage of between 8% and 30% occurs (depending on the product used). Alloys such as
bronze,
sterling silver
Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
'' Fine silver'', which is 99.9% pure silver, i ...
, and
steel also are available.
History
Metal clay first came out in Japan in 1990
[ citing May 18, 1990 (19900518) PJapan 2- 128447.] to allow craft jewelry makers to make sophisticated looking jewelry without the years of study needed to make fine jewelry.
Silver metal clay
Fine silver metal clay results in objects containing 99.9% pure silver, which is suitable for enameling. Lump metal clay is sold in sealed packets to keep it moist and workable. The silver versions are also available as a softer paste in a pre-filled syringe which can be used to produce extruded forms, in small jars of slip and as paper-like sheets, from which most of the moisture has been removed. Common brands of silver metal clay include Precious Metal Clay (PMC) and Art Clay Silver (ACS).
Metal clay artists looking for more strength in their silver creations can also mix PMC fine silver clay with an equal part of PMC Sterling clay. The firing of this alloy is found to be up to for two hours.
Another available alloy, EZ960 Sterling Silver Metal Clay was invented by Bill Struve from Metal Adventures, the inventor of BRONZclay™ and COPPRclay™. Because the clay is a sterling silver alloy, one of its best attributes is its post firing strength, in comparison to fine silver. This clay is fired open shelf on a raised hard ceramic kiln shelf at for 2 hours, full ramp. No carbon required. Its shrinkage rate is smaller than other clays, at 10–11%.
Precious Metal Clay (PMC)
PMC was developed in the early 1990s in Japan by
metallurgist
Metallurgy is a domain of materials science and engineering that studies the physical and chemical behavior of metallic elements, their inter-metallic compounds, and their mixtures, which are known as alloys.
Metallurgy encompasses both the sc ...
Masaki Morikawa. As a
solid-phase sintered product of a
precious metal powder used to form a precious metal article,
the material consists of microscopic particles of pure silver or fine gold and a water-soluble, non-toxic, organic binder that burns off during firing. Success was first achieved with gold and later duplicated with silver.
The PMC brand includes the following products:
* The original formula of PMC, now called "standard": fired at for 2 hours, shrinks by 30% during firing.
* PMC+ & PMCflex: fired at for 10 minutes or for 30 minutes; shrinks 15%, due to a particle size reduction. PMC+ is also available in sheet form which can be worked like paper; for example, for
origami
) is the Japanese art of paper folding. In modern usage, the word "origami" is often used as an inclusive term for all folding practices, regardless of their culture of origin. The goal is to transform a flat square sheet of paper into a f ...
.
* PMC3: fired at for 45 minutes or for 10 minutes; shrinks by 10%. It can also be fired using a
butane torch
A butane torch is a tool which creates an intensely hot flame using a fuel mixture of LPGs typically including some percentage of butane, a flammable gas.
Consumer air butane torches are often claimed to develop flame temperatures up to appro ...
by heating it to
orange heat for at least 2 minutes. It has a longer working life than the older formulations. It is also available in slip and paste forms which can be painted onto the surface of an object to be used as a mold.
* Aura 22: a 22-
carat gilding material, a gold paste intended to be painted onto the surface of silver PMC pieces, or ready-made silver objects.
* PMC Pro: a harder product which is only 0.900 fineness silver, hence it cannot be
hallmarked as
sterling silver
Sterling silver is an alloy of silver containing 92.5% by weight of silver and 7.5% by weight of other metals, usually copper. The sterling silver standard has a minimum millesimal fineness of 925.
'' Fine silver'', which is 99.9% pure silver, i ...
. It also requires kiln firing in a tub of
activated carbon for 1 hour at .
* PMC Sterling: is fired at and shrinks by 10–20%. Because of the copper content in this formula, firing is a two-step process; step one is an open-shelf firing and step two requires a firing pan with activated carbon media.
Art Clay Silver (ACS)
ACS was developed by AIDA Chemical Industries, also a Japanese company. ACS followed PMC Standard with their Art Clay Original clay (more like PMC+ than PMC Standard), which allows the user to fire with a handheld torch or on a gas hob. Owing to subtle differences in the binder and suggested firing times, this clay shrinks less than the PMC versions, approximately 8–10%.
Further developments introduced the Art Clay Slow Dry, a clay with a longer working time. Art Clay 650 and Art Clay 650 Slow Dry soon followed; both clays can be fired at , allowing the user to combine the clay with glass and sterling silver, which are affected negatively by the higher temperatures needed to fire the first generation clays. AIDA also manufacturers Oil Paste, a product used only on fired metal clay or milled fine silver, and Overlay Paste, which is designed for drawing designs on glass and porcelain.
In 2006 AIDA introduced the Art Clay Gold Paste, a more economical way to work with gold. The paste is painted onto the fired silver clay, then refired in a kiln, or with a torch or gas stove. When fired, it bonds with the silver, giving a 22-carat gold accent. The same year also saw Art Clay Slow Tarnish introduced, a clay that tarnishes less rapidly than the other metal clays.
Base metal clays
Lump metal clay in bronze was introduced in 2008 by Metal Adventures Inc. and in 2009 by Prometheus. Lump metal clays in copper were introduced in 2009 by Metal Adventures Inc. and Aida. Because of the lower cost, the bronze and copper metal clays are used by artists more often than the gold and silver metal clays in the American market place. The actual creation time of a bronze or copper piece is also far greater than that of its silver counterpart. Base metal clays, such as bronze, copper, and steel metal clays are best fired in the absence of oxygen to eliminate the oxidation of the metal by atmospheric oxygen. A means to accomplish this –- to place the pieces in activated carbon inside a container – was developed by Bill Struve.
Powders
Metal clays are also available as dry powders to which water is added to hydrate and kneaded to attain a clay consistency. One advantage to the powders is their unlimited shelf life. The first silver clay in powder form was released in 2006 as Silver Smiths' Metal Clay Powder. In the following years base metal clays by Hadar Jacobson and Goldie World released several variation containing copper, brass, and even steel.
Firing methods
Metal clay can be fired by a variety of methods. The three most common are:
* Electric
kiln
A kiln is a thermally insulated chamber, a type of oven, that produces temperatures sufficient to complete some process, such as hardening, drying, or chemical changes. Kilns have been used for millennia to turn objects made from clay int ...
- Kilns designed for metal clay are programmable and easy to use. All clay types can be fired by this method. This is the only way paper type and copper clays can be fired.
* Stove top- Either natural or bottled gas can be used, provided it reaches the temperature necessary to
sinter. Color of the piece determines the firing time.
* Torch- Any type of hand-held torch will work as long as it is hot enough to sinter the metal. Color determines firing time.
See also
*
References
{{Jewellery
Ceramic materials
Crafts
Fashion accessories
Jewellery making
Metalworking
Natural materials
Phyllosilicates
Products introduced in 1990
Sculpture materials
Clay