Discover Our Exciting New Line of Jewelry
All of the items in Skystone Designs section are done by a casting method, opposed to handmade, that is done in our Navajo Section. The important part of this section is, that we are presenting and selling, like in our Navajo Section, our own product. Each item from the beginning to the end, is made in our shop, and all is designed by Skystone Creations. The end finish of each piece is done by our Navajo Silversmiths. All items like: Pins, Pendants, Rings, Bracelets, Earrings, Bolas and Buckles, and Crosses are made out of Sterling Silver.
What do we need to know about Casting and Metals?
For most people, the pleasure of making jewelry comes from time spent at a workbench, actively driving tools to cut, bend and assemble a piece. Metals are made of crystals that arrange themselves in a regular pattern called a lattice. This has a lot to do with the physical properties of a metal. Metals with the same crystal lattice will probably have similar density, malleability, conductivity, and so on. Crystals, also called grains, are clusters of molecules gathered into units whose structure determines the ability of metal to bend, conduct heat and reflect light. All of these attributes are important to jewelers.
When grains are small, a sample will be harder to bend, more likely to break, tougher, and a better conductor of electricity. Large crystals make a metal more responsive to patinas and more malleable, except when the grains are very large, which causes the metal to become tough again. The usual way grains become small is through hammering or rolling. Do this enough and a sample of metal will eventually break, as the grain boundaries become too small to hold the piece intact. This process is called work hardening. Its opposite, annealing, uses heat to recrystallize the internal structure, building large grains from small ones. All of this goes on at a microscopic level.
Annealing temperatures vary with each metal and alloy, but as a rule of thumb they are about two-thirds the melting temperature of a pure metal. Annealing can be done as often as necessary.
By far the most common form of casting in contemporary jewelry making is lost wax waste mold centrifugal casting. It's a long name, but worth understanding because it tells us a lot about the process. The word wax tells us the model, or replica, is made of wax, while lost refers to the fact that the model will disappear somewhere along the way. Each model can be used just once. The waste mold part of the name tells us this is true of the mold as well - it too must be destroyed (or "wasted") to retrieve the casting.
Like the model, this mold can be used only once. We know that some metals, including silver and gold, will draw up into a sphere when heated. This explains why gravity alone is not sufficient to fill a large, detailed mold. And here the word centrifugal tells us what kind of force is used to push the molten metal into the cavity. Lost wax. Waste mold. Centrifugal casting.
LOST WAX CASTING
FITTING THE MOLD
BUILDING THE BETTER TREE
THE BURNOUT OF WAX
METALS and ALLOYS
This is a huge topic, even taken quickly, so we'll confine ourselves to metals used by beginning jewelry makers: copper, brass, silver and gold. Three of these are pure metals, while one, brass, is a mixture, or alloy, of two metals. Pure metals, also called fine, are often too soft for wearable jewelry, so they are alloyed as well.
Fine gold is given the arbitrary designation "24," so we can say that of 24 parts, all 24 are gold. In the case of 18-karat gold, 18 of the 24 parts are gold, with the balancebeing something of lesser value. If you write this as a fraction, 18/24, and reduce it, you'll see that 18-karat gold is three-fourths gold andone fourth something else. Generally speaking, alloys of 18K and purer are called high-karat golds.
The additive ingredients in alloys are used to affect the color, strength, ductility and value of the resulting alloy. In the case of yellow gold, equal parts of silver and copper are added. Rose gold ( also called pink gold ) is made by increasing the proportion of copper, and green gold is made by increasing the percentage of silver. Note that in all colors the proportion of gold remains the same. The most popular gold alloy for jewelry in the United States is 14 karat, which is also written as .585, or 58.5 percent gold. The balance can be anything, but it is usually some combination of silver and copper, except in the case of white gold, where platinum, palladium and nickel are used to change the color.
Pure silver is occasionally used in jewelry components, particularly when malleability is an asset. This us the case with bezels, which need to be safely pressed down againstgem. For most applications, however, fine silver is too soft, so a small amount of copper is added for strength. Hundreds of years ago, it was determined that the addition of 7 1/2 percent copper created a metal strong enough to stand up to use while retaining the warm shine of silver. This alloy came to be called sterling, and it is far and away the most commonly used silver alloy for jewelry.
A slightly baser alloy that contains 10 percent copper was used for hundreds of years in coins, and is therefore called coin silver. It is rarely seen today,, except in older pieces. Coins minted in the United States have not contained silver since 1966.
Copper is used in jewelry for its color, which is orange when polished, brown with normal wear, and green or blue after exposure to certain atmospheres. It is inexpensive, malleable, resilient and attractive, but its one shortcoming is the fact that copper not only discolors when worn, but discolors the wearer as well - typically by turning skin green. This is because of copper's eagerness to combine with almost any element that passes by, from oxygen to ammonia. Despite these shortcomings, jewelers value copper for its colors; it is usually patinated and sealed to protect the metal from further corrosion. Because its melleability is similar to sterling, it also makes an excellent practice material. It is slightly more difficult to solder because of its tendency to oxidize, but this means that a person who has mastered soldering by experimenting with copper will find the transition to sterling especially easy.
Another of copper's virtues is its affinity with other metals. As described above, copper is used to strengthen gold and silver. When alloyed with the low-melting gray metal called zinc, copper pulls a magician's trick to yeld a metal - brass - that is yellow and has a higher melting point than either of it constituents. By definition, brass is a mixture of copper and zinc, but the proportions can vary and will yield a wide range of results. The most common mix, called yellow brass, or CDA 260, is 30 percent zinc and 70 percent copper. As the proportion of copper increases, the color becomes more golden and the metal more malleable. An alloy of about 88 percent copper called NuGold is widely used in jewelry making, as are other low-zinc brasses.
Nickel silver, also called German silver, deserves mention not only because it is useful in jewelry, but because its name is so misleading. It contains no silver, and does not come from Germany. It is an alloy of copper, zinc and the element nickel. To see what it looks like, search your pocket change for a 5 cent piece. We should call this alloy " white brass " because it is so similar to yellow brass in cost, malleability, and the way it solders.