Vulcanized rubber mold

I’ve mentioned here and on Metal Clay Gallery that if I wanted a gold ring, instead of using gold metal clay, I would make the ring in PMC + (silver), then have it molded and cast into gold.

(I need a new wedding ring and am thinking of doing this, only with Platinum Sterling (R).)

Ruth wrote to me and asked to explain in more detal how one would go about having a ring cast.

First of all, my hats off to you, those of you who are brave enough to work in gold metal clay, I can’t bring myself to do it.

What is casting?

Let’s start off with a basic understanding of what lost wax casting is. It’s a method commonly used in the jewelry industry to make all kinds of jewelry and jewelry parts.

Here’s how it works: you make a piece of jewelry out of wax. Then you add a stick of wax to it, called a sprue. Attach that to a rubber lid, and put a steel flask on that rubber lid. The open end of the flask is up, the lid is on the table.

This will make a lot more sense if you open your favorite jewelry supply catalog and follow along, so you can visualize the various flasks and sprues.

Now, you would pour investment plaster over the top of your wax model and let the plaster dry in the flask.

Once dry, you flip the flask over and melt out the wax using a kiln or a steam de-waxer. The was melts out and is lost, thus the name, lost wax casting. (Sometimes people think the name means the method was lost.)

The next step is to force molten metal into the plaster, specifically into the space where the wax used to be. This is done with a centrifigal casting machine (at colleges and art centers) or a vacume caster (in the industry). There are also low tech methods, such as sand casting, steam casting and sling casting. (also potentially dangerous.)

But I’m not trying to teach you to cast, just to give you a basic idea of the process.

For more details, here’s a video of the process. Here’s a link to more videos on technorati.

But wait, you say, I don’t work in wax, I work in metal clay!

No problem. A professional caster can make a wax for you from your metal clay original. How? By making a vulcanized rubber mold of it.

The steps to the process are:

1. Choose your caster.

2. Make your perfect model ring, polished, fits and completely done.

3. Call up your caster to discuss your order and let him/her know that it’s coming.

4. Mail or hand deliver your model ring to the caster, with clear written instructions.

5. He or she will then — make a rubber mold of your ring and shoot a wax from this, then cast the ring in the metal of your choice.

6. Then the caster will finish the ring to the degree you specify and pay for. The range goes from just roughly cutting off the sprue and sending it to you, to cutting off the sprue and sanding it down, all the way to a complete finish and polish.

Make sense? Please post questions in the comments so I can clarify things.

I know one question will be how do I find a caster? The best ways are to ask people you know, ask on your email lists, and contact the casters who advertise in your favorite jewelry-making magazines.

Some casters work only with the trade. Those who are advertising in the magazines available at your local bookstore are open to working with regular folks, hobbyists and small businesses.

Click here to learn more about Platinum Sterling (R).

(c) 2008 Elaine Luther All Rights Reserved


What’s that in the picture? That’s a vulcanized rubber mold. Please note that it’s not a very good one, but it’s one I happen to have lying around. My good molds are all on file with my caster.

Technorati Tags:
jewelry making, lost wax casting, casting, metal clay, precious metal clay, art clay silver

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