Friday, 5 December 2014

From the Wax

Comes the Silver

I promised a followup on the lost wax casting. When last seen (Nov. 24), my three wax models were all on sprues, ready to invest.

I didn't take any photos of the invested metal flask because there really is nothing to see — just a length of pipe filled to the brim with plaster. That investment material needs time to set. As little as a couple of hours will do but for the class, we left them for a week.

Fire It Up

On November 30, things got more interesting — way more interesting.

Here, one of the class is melting silver pieces in a crucible. This is being done for a hand pour into a bucket of water. If done just right, it can produce some quite interesting small silver blobs. A few resembled elf hats and lots were like miniature bowls. I'm afraid I poured mine too fast and the blobs were, well, just blobs.

While our flasks finished the wax burn out in the kilns, we undertook this exercise for practice in melting silver (and probably to remind us how intensely hot things get during this process)!

To see the real drama of casting, with a flask and crucible whirling in the centrifugal casting arm, visit the Creative Jewellers Guild Instagram site:

Fishing for Silver

Once the silver has been flung into the cavity left from the wax burn out, the flask is removed (with tongs and great caution) from the casting arm and plunged into a bucket of water. It bubbles and hisses — duh — for a few moments as the hot investment starts to dissolve and fall out of the flask. Pretty soon, the water is warm and very muddy. Somewhere in that mess — hopefully — you will find your silver castings. Fish for them, take a toothbrush, remove the last of the investment and admire your work.


Okay, things do not always go as per plan. The bottom of my ring shank blew out during the cast. This is not a total disaster because the part that would be hard to fabricate is that pair of arms to hold my silver bead. I can cut away some of the damaged shank and manufacture a ring to mount it on.


The other bits fared better.

Above is the wee tiki I carved. As you can see, there is a lot of polishing to be done but the item is there.


All shiny and sitting on my Kindle reader.

I'm pretty happy wit this little guy. It was fun and I plan to find a way to do more casting in the near future. Certainly the only way I could have made this item.