Stones cast in place & the "stone pendant"

Test #2 fresh out of the mold

 In yesterday's post I wrote about my efforts to develop my process for casting stones in place. I should add that I am setting them nearly flush with the ring surface too. You've seen this of course. I'm not clear how many folks are casting them in place or are Pave setting them. Pave is a technique I have not tried. It involves pushing the metal around the stone into the the stone to hold it fast. This is done with hammers & various punch or chisel like tools. Then the metal is made smooth by hammering, filing, sanding, etc. Casting in place is promising because it not only save labor but it seems potentially less risky for stones that will tolerate the temperatures.

To the left here is the #2 test right after I de-molded it. I was thrilled to see the bright stones looking out at me from the scale. All five made it this time!

Test #2 after finishing.

The scale is particularly heavy this time. I owe this to keeping the flask at 1350° F for the pour. I have in the past been lowering it to 1100° or 1200° F. I'm not convinced this is really the reason. More trials will tell.

To the right is the #2 test after finishing. This is more of a matte finish done with the magnetic pin finisher.  I'm really happy with this ring and I'm keeping it!

So now we can move onto colored stones and the production versions of the women's Rivers series.

Below is a picture of waxes for new design and process. What I am doing here is taking impressions from interesting stones I find and turning them into a pendant or other pieces. I started with a pendant because this stone's impression looked good as a pendant. I was actually looking for a pattern in it that would work as earrings but it's just not there.

Stone pendant waxes

The process begins with finding stones that have textures and shapes that might work as pieces of jewelry. I have pretty good 3-D perception. Even so this can be challenging. Once I find a good stone the process looks basically like this:

I clean it up with soap & water

Make matching negative and positive molds of it with silicone

Create a spacer between the molds for the thickness I want

Then inject wax into the mold

The result is a thin wax piece that has a mirror image of the stone's surface front & back.

Each wax is trimmed & shaped by hand at this point. Eventually I will pick a few of the best pieces and make molds of them. 

Then the waxes are attached to sprues & vents and invested in plaster. The investment is followed by the wax burnout process and then the molten silver is poured into the remaining plaster mold. Following the pour the silver pieces are then de-molded and finished. 

Hopefully in the next few days I'll have some cool looking pendants to show you!

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Developing my stones cast in place method

Test ring -w- rough finishing

Whether they tell you or not, jeweler's test their processes. Sometimes you get lucky and your test pieces are sale-able, sometimes not. This stones cast in place process is not only new to me, it is relatively new to the industry in general. Little is written and what is lacks details, at least as far as I have been able to tell. This posting included! Sorry. As time permits I will try to add more. There is A LOT going on here.

Anyway, testing for this process is essential. So here we go!

Last night I finished the first test of casting some cubic zirconia stones in place. The stones survived, the setting method works, and the stones are very well set. This one has been polished up a little just to get a feel for the look. Of five stones, each set in a slightly different way, two were very good. Two were set in a way that trapped some "schmutz" behind them so they look brown. I had written off the smallest one but it came out pretty well anyway.

Test ring, desprued, & descaled

The photo on the left is of the ring after some quick finishing. I just wanted to get a sense of how the stones might look after a ring is finished. A high polish ends up making some defects more evident. So this is a good way to see what's going on.

To the right is a picture after the piece had been de-sprued and had the fire or casting scale removed. I usually call it "schmutz". Scale is a combination of metal oxides and other compounds that form when the surface of the hot hardening metal encounters oxygen and the compounds in the investment plaster. It is removed by a process involving light acid etching (the pickle), scrubbing, ultrasonic cleaning, and in my case magnetic pin finishing (which is really a tiny, tiny hammering process).

All the different holes were put there in case the casting process failed. Then I would have had to try some mechanical setting methods such as Pave.

Test ring wax, sprued & vented

Here to the left is a picture of the wax which has been "sprued up" prior to investing in the plaster. The red and dark blue sprues & vents are pre-fabricated wax rounds or "wires" sold specifically for this use.

One difference in my casting process is that I use vents and a vacuum process. Most jewelers do not so they can conserve material costs. Instead they rely on either pressure or vacuum methods alone to help the metal flow.
Venting is standard in larger castings such as those for cars, planes, or other industrial parts. Those molds are so large that applying vacuum or pressure in most cases, is not practical.

Venting allows trapped air and the various gases to flow out of the mold directly rather than through the investment material, which is actually fairly permeable to gasses. This helps eliminate the need for pressure to force the metal in to displace the gasses or vacuum to pull the gasses through the investment material.

Of course anything goes. The more expensive and critical the part, the more extreme the process. I have read about but not actually seen vacuum & pressure casting methods used for large parts too.

To me time is money. Venting results in a more reliable casting and less rework. I am also constantly fine tuning my sprue sizes and shapes to improve the casting quality, reduce rework, and conserve materials. Over time this will allow me to pass some savings along to my customers.

I continue to utilize vacuum since the gases continue to form even when the mold is full. Pressure pockets can still create voids and deformations. Vacuum applied to the outside of the investment helps remove the gases & reduce problems resulting from these gases. It's a relatively easy and affordable way to save time and improve quality so why not?

The second test will be tonight with attention to the getting a more finished setting out of the cast directly. When the quality is right I'll start the production pieces.

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Creative Process - Rivers Ring Series

Making Of a New Design - Lost wax & creative process

Waxes; finished, raw, just carved

One of the great things about the modern lost wax process is we can quickly come up with multiple designs in wax. Then we can create silicone rubber molds of those which are use for making additional waxes. These 2nd generation waxes can be either used for more 3rd generation rubber molds or customized for a particular client.
Once a wax is done it is "invested" or cast in a plaster mold. After the plaster is fired in a kiln to 1350ᴼ F it receives the molten silver. We'll talk about the investing & metal casting processes more in future postings. There is creative potential in those steps. But, most of the creative process is in the creation of the waxes and the finishing of the cast pieces. I find that during investing & casting I am mostly focused on not screwing things up!

My Creative Process

In my process I allow three primary influences on my shapes:

• Natural shapes - Water, tree bark, leaves, pine cones, soil textures, fractured & smooth rocks are just a few of the things I look to.

• Materials - Metal, wax, plaster, wood, fabrics, and other materials are used in the creation of jewelry. Just like a clothing designer uses the nature of their fabrics I like to use the nature of the materials I use to influence the shapes of the jewelry we make.

• Tools - Rather than see tools as things to force materials into my vision I chose to consider how each tool can influence the shape itself. Does a saw mark or the cut of a chisel present an opportunity to expand or enhance the design? Should sanding scratch be eliminated or does it present the basis for an interesting texture?

Creating the Rivers Series

Three designs for the Rivers ladies rings

The Rivers series began with a prototype that was originally intended to expand on a friends ring based on the "all seeing eye". I wanted to demonstrate a less abstract design.

I began with a purple wax ring stock. It was cut to about 3/4" & sized with a reamer. This wax is hard, more like a soft plastic. To begin making the eye shapes it was drilled. Then saws, carving tools, and files were used to make the shapes.

An interesting thing came out of this. Once I had created a number of differently sized and oriented eye shapes it was apparent that it was developing a fluid character. So I ran with this a bit more. Seeking a way to enhance it I tried a technique I had used in a wax for a large bronze sculpture; directly heating the wax with a flame. It worked pretty well.

The three designs in finished wax

The Rivers I sterling silver men's ring is from the 2nd generation wax of the prototype and has been made more fluid. The Rivers III ring is from a 3rd generation wax where this method of heat & flame shaping was taken further. The Rivers VI men's ring is also from a 3rd generation wax that I took in a direction that the blue wax I was using took me. This particular wax will develop a nice beaded shape along hard edges if heated just so.




Reduced back band for smaller fingers

Narrowed back for small fingers

The photos above are of the Rivers ladies series waxes. These will have four synthetic stone cast in them. As my wife said, a little bling would be a nice addition!

The picture to the right here shows a more practical design consideration. This ring is being designed for women. It will be made in sizes 5 - 9. The smaller the finger, the less room there is on the inside when the hand is closed or is gripping something. A wide ring can be uncomfortable. These rings are intended to be worn daily so I am doing this so they will not become annoying to their new owners during day to day wearing. This also allows the rings to be resized by any competent jeweler at a reasonable cost. Keeping your customers' comfort and practical needs is as important as a unique design.

I hope this entry was interesting and informative!

Best,
John

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