This ring was born in our store this past month. It isn’t just a simple process of scraping a chunk of silver off a block and gluing a gemstone down inside. It takes just a bit more work (and equipment!) than that…
Here you can observe- in painstaking detail- the conception, gestation, and final delivery of a custom designed ring from Wexford Jewelers.
It all begins with a wax model. This is extruded sheet wax that has been bent into the primary form, cut to shape, cut to size, and hand heated. Wax can be brittle, and working it- ever so gently- in the hands for a few seconds makes it more pliable, which will result in a cleaner finish.
Here I am adding detail- again, extruded wax. There are different kinds of wax- injection, extruded, & carveable. Extruded is exactly as it sounds- it is pushed through a form for various shapes, thicknesses, and applications. Although the majority of our waxwork is done with injected forms from our own molds, this particular ring began with extruded. I suppose it doesn’t look like rings most of you are used to seeing, but that’s how we roll. The squarish internal shape fits the natural contour of a finger much better than a standard circular band.
The rest of the detail and construction of this ring would take up a bit more time than we want to spend today. I will post a full wax construction project in a future post, today we are focusing on getting the wax to be metal.
Here is the finished wax. You can see the prongs, the detailing, and yes- there *is* a stone in there! All obsessive compulsive readers are right now wondering if we’re going to forget, and leave it in there. Well, we are. Not, however, because we are dumb. That stone is a sapphire, a member of the corundum family, and smaller sapphires can handle heat. Sometimes, not all the time, we cast sapphires and/or rubies right into a piece. They have to be small, have properly built holes underneath, and be free of major inclusions. This one meets that criteria.
These are mold bases. Made of rubber, they are engineered to flex onto and off of the flasks.
This is a flask. There are a couple of kinds of flasks, ours are designed for vacuum casting, which we will learn about soon.
Using this somewhat primitive alcohol-burning lamp, Jason heats up a sprueing tool…
…and attaches the wax to the mold base. That ‘stick’ connecting the ring to the mold base is called a sprue. Sprueing is a delicate art, one that we are all continually mastering. The sprue has to be big enough for metal to flow in, but not so thick that it cannot be cut off. If the sprue has any sharp turns, the molten metal can actually break shards off as it flows around them, but if the sprueing is done thickly and haphazardly, you have a weighty mess to clean up.
Jason attaches more items. We rarely, if ever, cast one piece solo. For the amount of electricity, time, and work that go into casting one flask, it would be almost silly to do them one-off. We multitask as often as possible.
The mold base is very carefully slipped onto the flask, and our little items have a home. Now the flask is ready to fill with ‘investment’- once the holes are plugged,
…with a little bit of masking tape!
This is the investment. It is a silica-based plastery substance, a light powder that is mixed with water. Jason always wears an industry respirator while doing this, as silicia does not naturally flush out of the lungs.
In this photo, we’ve mixed it and are currently de-airing it- simply removing the bubbles in a vacuum machine.
Pouring off the mold. This must be done quickly, as it begins to harden immediately. But it also must be done not so fast as to: 1) trap air bubbles that will deface the designs, and 2) possibly snap or break fine wax detail. Tricky, tricky.
…pouring,
A second de-air process removes any little bubbles that may have trapped under detail or in little crevices. This vacuum machine serves a host of uses.
During the de-air process, the liquid investment appears to ‘boil’. Its just the air seeping out.
Four flasks, filled and ready for de-waxing. Each flask will be cast in a different metal. Now we let the molds sit for a bit and harden up, in preparation for the next step…
After about an hour, Jason gently pries the rubber mold base off the bottom, and sets it aside for next week’s cast. Most casting tools will be re-used for decades.
See the wax poking out of the bottom? Soon this will all melt away, leaving a cavity shaped exactly like the designs. The sprues work as feed lines for wax to go out and metal to go in.
The four molds are placed inside the steamer unit. This does pretty much what it sounds like- fills with steam, which melts the wax right out of the investment. This is the part where I begin to get just a touch nervous if I have a big job- once that wax melts out, if something goes wrong, it’s back to the drawing board!
The molds that we left in the steam de-waxer have lost more than 90% of their wax. They are now ready to enter the next phase of casting! Here is the de-waxing machine:
Not very impressive by itself. Here is the inside, after a de-waxing. Note the residue of bright red wax on the grate.
We are in the process of changing over to a nice shade of blue, it will be interesting to see the color layers after that!
Here are some of the various alloys we use. Different levels of hardness of white gold, a fine blush rose gold is visible there in the background, and a rich yellow 18k alloy are just a few. The pure metal is stored in a time-release safe, and will be counted out, grain by grain, measured, and calculated with the appropriate alloy.
The burnout kiln stands at the ready. This one is capable of a timed temperature ramp, up to appx 2000˚F.
Inside the kiln. Not only will the extreme heat (1350˚F) vaporize what little wax may be left, the heat will also serve to harden the investment, bringing it to a pottery-like density that can withstand liquid heavy metals sloshing down into the cavities.
Tools stand at the ready. We use a welder’s torch, but have also used an electric melter in the past. The white bowls are crucibles, the black rods are graphite stirring rods, and bin at the back is casting slag.
Jason now places molds in very carefully. At this point, they are at their most fragile- the wax is gone, leaving thin pieces of plaster investment in between details. The investment has not yet baked to a hard consistency. The slightest jar can knock shards of investment into the mold, which metal will not cast over. This will leave literal chunks missing from the final cast design. Not only are they fragile, they’re hot! He programs the kiln to ramp up in temperature, from room temperature to a scalding 1275˚F. This is done over a period of 10 hours.
10 hours later…
Here is our alloyed white gold (not this ring, but the same cast). Gold always comes from the ground yellow, but can be alloyed into white, rose, or various other shades. The alloys you see here are primarily nickel, silver, bismuth, and palladium. Stupidly, I failed to get a shot of the raw silver alloy
The vacuum caster stands ready. We used this yesterday to de-air the investment, remember? Our company used to utilize a centrifugal spin caster, but the vacuum casting setup takes up less room, so we went with that option, for now. Vacuum casting is also somewhat safer, as there is no chance of hot molten metal slinging around the room!
What is this unsightly thing?
Why, it’s our custom made ventilation hood- drawing out toxic fumes from the vaporizing wax, gases from the melting metals, and the stifling heat.
Jason fires up the torch and applies heat to metal.
I love this photo:
More heat, a pinch of flux, and a stir with a graphite rod…
The flux is a cleanser for the molten metal, not only bringing impurities to the surface, but also acting as an oxygen barrier. Primarily boric acid and powdered glass, flux comes in a light dust that must be mixed with the melting metal.
The flask is fit snugly into the machine, all seals are checked, and the vacuum is switched on. Our machine pulls 29 inHg, sucking air out through the finely porous investment.
Pouring the metal:
This must be done when the metal is at the perfect viscosity and temperature- too hot, and the alloys will begin to smoke off, too cold and there will be an unmelted sludge of alloy that is not mixed into the gold or silver properly.
A perfect ‘button’
The button is that glowing nub of metal you see here. It is the extra weight that helps drive the molten metal into the crevices of detail. The metal is still glowing because it is still about 1100˚F.
Sixty seconds later, the button is cooling and I somehow lost camera focus:
The hot flask is set in our far back room to cool. It makes a lovely ‘crink-crink’ sounds as the temperature drops and the metal shrinks.
The last step:
Jason cleans out the crucible. A quick blast of heat melts the vitreous flux, and any tiny droplets of metal left behind fall out. The crucible is now ready for the next batch of metal! First, a little snippet of history: This ring was originally designed and made by me for Ben, a friend of my husband Michael. Somehow the ring was lost. There’s always been a suspicion that my youngest child had something to do with it… but without evidence she has full habeas corpus.
(Possibly the culprit behind the first missing ring, but she is now four and knows not to touch Mommy’s creations anymore.)
Ben missed his ring for quite some time, and this year his wife Amanda, who came into the picture after the ring and had not yet seen it, commissioned us to re-create it, as close to memory as possible, for his birthday. We did fall short of the actual day (sorry, Ben!) but he has it now, and is enjoying it once again. Lucky for him, we had exactly one more center stone that matched his old one!
Back to the work at hand:
Here is Jason with the (somewhat) cooled flask, ready to chip out investment. It’s still the approximate temperature of a warm oven, so he protects his hands. Note the trusty screwdriver at the ready.
The sharp screwdriver plunges into the investment, Jason uses leverage to cut and crumble chunks out, careful not to hit the metal inside.
The investment comes out quickly, and once the edges are cleared, Jason can tap on the button to loosen the rest.
Is that shape beginning to look familiar? It is to me!
The metal is still hot to the touch, but the air is cooling it rapidly. In the past 15 minutes the metal has gone from beads of alloy and pure silver (called ‘shot’) to a completely molten stage at over 1200˚F, then hardened into a completely new and different shape! Soon it will leave its warm cocoon of silica plaster and face more heat- this time from friction.
Jason taps a bit more investment off, and the shapes are even more visible.
Standing at the bathroom sink, Jason scrubs the casting off under running water, using an old toothbrush. We make sure to mark the investment toothbrushes so no one eats silica!
Here it is in all its glory:
The powdery investment gives the metal a silky look. I have always loved this look and kind of wish we could leave it intact. Sandblasting gives a nice even matte, but never the exact same fineness of texture as this…
See? The sapphire perfectly handled the heat of casting. I love corundum.
Next step:
A good ultrasonic soaking will get off any more investment residue. This is something of a ‘starter’ ultrasonic for the industry, but it worked for the picture.
Doesn’t that blue look appealing? I just want to take a swim in it… It’s just an industrial strength cleaner, sorry.
The ring is cut from the sprue, and Jason proceeds to grind the bottom nub off where the sprue fed into the piece.
This is our jeweler’s lathe. We use it for multiple stages of grinding and polishing. The wheel that is on in this pic is an aluminum oxide composite made by 3M. The wheel rotates at 3,475 RPMs, so friction is considerable. 3M designed the wheel to be porous, which absorbs some of the heat. Jewelry still gets very hot, however, especially a natural conductor like silver!
If Jason would happen to slip and hit his fingernail on that wheel, it would cut through to the quick in about 3 seconds.
A trained hand can roll the ring, cutting the proper contours into the metal as the wheel spins.
Now Jason applies a file to all of the topmost surfaces of the ring. Often a cast will come out with little chunks missing out of the design, sometimes there is a small amount of flashing that needs to be scraped or ground off. Jason is prepping this one for his wife (my sister) to set stones.
The ring is now 80% done. Note the ingenious pink ‘shim’ on Emily’s bench pin. We’re all about technology here!
The next day:
Emily announces her presence by threatening the camera with a Foredom handpiece:
With the handpiece whirring at about 12,000 RPMs, Emily begins to notch the prongs.
Here she trims the height of the smaller side prongs.
After notching the center prongs, Emily checks the fit by slipping the stone into its seat. This particular stone is a checkerboard cut topaz.
It fits! Now to level off the prongs:
I build the prongs a little longer than needed in the wax, in case of a tighter fit. Emily always cuts them back in the metal for a perfect fit. Setting a faceted gemstone is a delicate balance- there must be full support beneath the stone, enough pressure on top to hold it in, yet not too much pressure to crack the actual piece or cover the natural beauty and light refractive properties of the gem.
Okay! It’s in, and the prongs are now set to be bent over the top of the stone:
It may look like she’s just crunching down on that stone with pliers…
… she is, just very, very carefully. It took her years to learn how to wrangle those pliers just right!
Setting the sidestone, an aquamarine:
Checking the settings for wiggle:
Emily is not actually dragging that file right across the top of the stone, she’s actually working on the silver immediately on top of the topaz. Once the prongs are notched and bent, there are always rough spots to be smoothed down.
Now Emily takes a medium-grit silicon dioxide wheel to the prongs:
The silver needs to be ground gently, almost massaged into the shape we want it to be. One false slip of that wheel, however, and there will be a nice scuff mark halfway across the top of the stone. Stone setting requires an incredible dance of strength and grace…
Now it’s off to the lathe again, this time with a compact muslin wheel embedded with polish rouge:
One more dip in the cleaner, some polishing on a finishing wheel, and Ben’s ring is complete!
Happy birthday, Ben! Don’t lose it this time. Amanda: thanks! :)
For more photos of this process, visit our flickr photostream.
For your own custom experience, email us.
