Lost Wax Casting Technique

So I started taking silversmithing classes again, this time in San Diego (as opposed to Bali) and had to re-learn quite a number of things. I had adjusted to the Balinese way of making jewelry, which was quite a difficult transition, and now I was coming back to more modern ways of doing things. It felt like I was a new student, trying to grasp everything all at once again.

I found this quaint place in Hillcrest, where students are free to roam in and out of class like a gym, and take as many hours of free shop time as they please. This fit my schedule so well (although it would have been nice if it had midnight or 1am classes for night owls like me).

In the past, I’ve learned how to wield, shape, heat metal to its desired form. But I had yet to create a mold and basically work backwards, to create the intended shape and style of a ring before even touching the metal. So of course, in true Christine fashion, I wanted to learn the most difficult technique which would take up my entire class time just to achieve: waxing, investing, burnout, depositing molten metal into the flask via centrifuge and refining the investment before setting stones. Yikes.

As instructed by my teacher, I began to brainstorm some ideas for rings to carve. This one had to be out of this world, and definitely more difficult than anything I’ve done previously. I decided to create a large ring consisting of waves, with smooth rims and stones flowing through the center on two large crests either through a channel set or bead set. True to my style, it was going to be magnificent, simple, elegant – at least that’s what I had conjured up in my head (see below).

 

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I had chosen a variety of sizes, a range of colors, and a spread of stones for the waves. Aquamarines in at the height of the wave, and sapphires to finish the edges off.

I thought I was ready to go. I showed the above picture to my instructor and he laughed. He told me that the next part was going to be hard for me. I had to recreate what I envisioned in my head directly onto paper. As many of you may know, I’m all cerebral when it comes to doing things. If I get a random vision at 3am, I’ll have to pull myself out of bed to make the literal piece, not write it down. Seemed like such a waste of time to jot something down when you already have the perfect picture in your head. So you can imagine my mortification when I was instructed to create a sketch, true to size, shape, measurements, EVERYTHING, so that my instructor could see what the heck was going on in my brain.

 

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And yes, that’s the outline of my hand. Remember when you had to draw hand chickens in kindergarten? Yup. Traced my fingers for this sketch in the same way. Felt really silly at first, like I was being tested. Not bad, right? Well then I had to take this and basically recreate it with a piece of wax. Literally, a chunk of wax. And how did I do it? Very slowly and carefully. With random etching, carving, shaping, wittling, sanding and, sawing tools to be used at my disposal.

I didn’t fully appreciate the amount of precise work that needed to be invested into this little piece of wax, until after the fact. Basically, the wax had to be the best version of the ring I could make. Any slight scratch, dent, you name it, would appear in the metal once I casted the ring. Pretty amazing. And annoying. The hardest part was staying true to my design. Sometimes when I make wireworked jewelry, I go off on a tangent from my original thought and create wondrous pieces. Because wax mold carving needs a preset model, I was forced to keep the thickness of the ring at 1.3mm, and the rims at 3.0mm, and the waves in all the measurements of the stones I had planned for already. Pretty hard to do when you are still learning how to work with wax. I ended up breaking my ring in half in week 6 and almost died. Fortunately, wax melts, and you can repair any damage you inflict on the poor mold.

So after all the whittling, I finally was ready to set my mold. We needed to create a way for the wax to flow out of the mold so we connected some little legs of wax to the ring for it to create a convenient outlet for when we bake the mold and the wax melts out of the flask.

 

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We used a lost-wax casting technique, where the wax model is melted away to create a hollow area in the middle of the mold. At one point, I felt like I was baking a pie – we went into the back room and created the mold formula with a flour sifter and mixed it up before pouring the contents into the flask where the wax carving sat. This was then baked in a kiln to melt away the wax to make room for the metal.

 

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The next week, I cut pieces of silver from coins and other fine silver scraps to create my sterling silver content (92.5% of fine silver, the rest an alloy mix). I poured these bits and pieces into the chamber of the centrifuge marked “silver” in the photo below. The other end was going to be loaded up with my new hollow mold, ready to catch whatever was going to be spun out of the silver compartment.

 

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Then I heated the metal up to its melting point – the metal looked like the T1000 in Terminator 2 (sorry, it was what I kept thinking about when melting the silver and alloy). It’s ok, I totally looked like Marvin the Martian in my flame resistant helmet.

 

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Once the metal alloy heated to 961.78C (probably hotter, since I had to make sure the fine silver and alloy mixed properly, so let’s say 1000 degrees Celsius, the spring on the centrifuge was released. The liquid metal shot into the empty portions of the flask and filled it perfectly to make my ring through the centrifugal force of the spinning.

 

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I seriously had to wait about 5 minutes for the flask to cool down enough to gently place it (with a large pair of heat proof tongs) into the cold bath water (it still sputtered like a sunken ship). Then, I slowly dug out my little trophy of silver with a spatula and wooden stick.

 

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After sawing off the legs with a jewelers saw, I started the laborious part: smoothing out the kinks. I realized that every single flaw I overlooked while making the wax where found right where I left them. In the heated pursuit of getting to the end, I forgot to put on a new set of eyes during the refining process while carving the wax model, ones that would examine every nick and scratch. It’s much harder to erase these flaws from the metal than from wax, so lesson learned! I spent some laborious hours sanding away the fine scratches I carelessly left on the ring in wax form.

Then, it was off to being polished. I used some industrial sized sanding machines laced with Trippoli, which buffed my ring to a mirror-like shine.

The stones were the last step. I have gone over and over in my head whether this is an area I wanted to learn on my own, and I always fluctuated back and forth. I decided for the sake of my time, sanity, and business, that I would find the best stone setter to work alongside to ensure that my clients were getting the best, not just the “now” from me. It’s probably going to take me years to perfect this technique, and I’d rather offer this part of the design element to my clients as early as I can.

A bead setting of the aquamarines and sapphires complemented the wild waves in the ring perfectly, almost looking like sand. Voila!

 

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I knew that it was worth my class time to figure this piece out. And I’m glad that I did it. Hope you enjoy it! More designs to come.

 

 

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