Silver on the Ceiling: 7 Expert Jewelry Casting Tips
“There was silver on the ceiling!” Ever done a happy dance after something came out right on the first try? It doesn’t happen often. That’s what makes us appreciate the value of knowing not just what to do but how it works. Without knowing where the edges of “works” are — beyond which a step breaks down — it’s easy to slip into trouble. Successfully adjusting your approach to keep within that working zone depends on a broader understanding of your process. So does your ability to fix the inevitable problem when it occurs.
ABOVE: Ken Newman’s Sandcast Belt Buckle project appeared in Lapidary Journal Jewelry Artist February 2010; photo: Jim Lawson
Ken Newman, who wrote that memorable opening line in a project called “Sandcast Belt Buckle,” wasn’t doing a happy dance that day but it wasn’t a total loss. “My first attempt at sandcasting had failed in spectacular fashion,” he admitted. Then he described how his more experienced father explained what had gone awry. When heated, too much water in the sand had turned into enough steam to blow the metal sky- or at least ceiling- high. His father showed him the right consistency, and a shaken but resilient Ken tried again, with success. “That was 1970,” he wrote in 2010, “and I remember it like it was yesterday.”
Good Things to Know
Here are a few of the many lost wax casting tips and favorite tools Sara Sanford offers in her in-depth 2002-2003 Lapidary Journal series on that ancient technique. And, oh yes, she explains, amplifies, and adds caveats about how these work — or don’t.
1 Avoid Metal Pitting and Tool Damage
For carving wax models, Sara says, “#2 and #0 cut metal files are very useful, along with coarser rasps, which don’t clog easily. But do use separate files for wax and metal. It may not be significant if you get wax filings in your metal, although this can lead to problems with soldering or polishing. But it does matter very much if metal filings get into your wax — this will cause pits in the casting. When files or burs get clogged, a quick backward swipe on your pant leg may unclog them. If not, use a brush file cleaner. Under no circumstances heat a file or bur to rid it of wax — this will ruin the tool.”
2 Make a Bead
There are many choices in available carving waxes. “A water-soluble wax can be used for the core of a hollow bead or other object. A design is built up on the outside, using sheet, wire, or injection wax — carving wax has too high a melting temperature. When complete, the model is soaked in water for a few hours to overnight. The inside core is dissolved, leaving the exterior intact.”
3 Modeling Organics
“One major problem” with casting some organic materials is that “the finished cast object may be too heavy to be practical as a piece of jewelry.” One way around this: “cutting the item in half, and hollowing out the center, casting the two (or more) pieces separately, then soldering them together after casting.” Other organics “may be too thin or fragile to cast well. In this case, adding wax as reinforcement, to the back of a leaf, for instance, will make it substantial enough to cast. You will lose the natural form and texture, however.”
4 When in Doubt, Add a Sprue!
That’s Sara’s rule of thumb for creating the channels that let melted wax run out and leave behind a mold for metal to run in. “Metal does not like to flow through restricted spaces, so adding one or more extra sprues to areas that are delicate or far from the main sprue will help guarantee a successful casting. Yes, it does take more metal to cast, and also more time to remove the sprues after casting,” she acknowledges. “But how long would it take to make the wax model over again? However, don’t put a sprue to the very top of the model if the metal has nowhere to go beyond that point — place it farther down.”
5 & 6 The Environment Matters
Moisture is a big issue in casting. Both water and air quality can make a difference in your investment. That’s the plaster-like material you use to coat your wax model on your way to creating your mold.
“Minerals or impurities in the water used to mix investment can adversely affect the quality of your casting. If you live in an area with very hard water, you might want to use distilled instead of tap. Some suggest leaving the water to stand overnight to allow it to ‘settle’ or for air bubbles to be released. . . .
“Investment has a relatively short shelf life, especially if you live in a moist climate or don’t keep the container sealed. As the investment absorbs water from the atmosphere, it begins to clump, reducing its ability to conform to intricate details on the wax model. Manufacturers of casting investments have gone to great lengths to make mixing a science rather than an art,” adds Sara. “Any departure from their recommendations will be at your own risk.”
7 Steady Pour
“Regardless of what type of casting machine you use, you will need a container, or crucible, in which to melt metal. . . . My favorite for gravity pours is the Burno-style crucible. It has a bottom, or dish, where the metal is melted, and a hood which covers half of the bottom. This hood helps retain heat, allowing the metal to melt faster and remain molten longer. The bottom also has a notch for pouring the metal out . . .
“I have permanently attached tongs to my Burno crucibles, which is much safer than trying to hold the two parts together while pouring molten metal. Use heavy-gauge iron binding wire, or brass wire, about 16 gauge. Leave the ends sticking out after you have wound it tightly around the tongs, making a couple of legs. The crucible will be more stable while you melt metal. The hole in the hood should be on the opposite side of the pouring notch on the bottom. Although this seems counterintuitive,” Sara remarks, it’s not. “Its purpose is to provide a vent for the flame. This prevents it from being blown back onto your hand holding the torch.” And avoids burning your hand or extinguishing the flame, she concludes.
Keep yourself safe and your flame for jewelry making burning bright by learning the what, how, and why of your techniques.
Merle White is Editor-in-Chief of Lapidary Journal Jewelry Artist.
Find the Entire Lost Wax Casting Series
Sara Sanford’s exploration of lost wax casting ran in multiple parts in Lapidary Journal in 2002 and 2003. The series includes seven technique features, a two-part tool-making project, and a four-part jewelry-making project designed specifically to provide hands-on experience at every stage.
- Tools for Wax, July 2002
- The Right Wax, August 2002
- When in Doubt, Add a Sprue, November 2002
- Smart Investing, December 2002
- Burn-Out Is a Good Thing, January 2003
- Going for a Spin, March 2003
- Casting Call, May 2003
- Wax Pen, July 2002 – August 2002
- Casting a Gold Pendant, November 2002 – February 2003
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