Many Faceted

Casting, Part 2

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Today was Day 3 of Casting class, so here’s the rest of the wrap-up!

My cast silver ring, cleaned up and ready to finish and polish.

Before class started, I borrowed a coarse file and removed the remainder of the sprue from the bottom of my ring, so it’s now ready to (more finely) file, sand, and polish. (I ran it through the magnetic tumbler, which shined it up somewhat, but also scratched it up quite a bit, so in hindsight I wish I hadn’t bothered with it. Oh well.)

Since I forgot to photograph it yesterday, this is the kiln. ...and this is the vacuum machine. The left side is where a bell jar would go; the right side is used for vacuuming out a flask.

Today we were vacuum casting, and it did seem to go somewhat faster than the centrifugal casting (in part because the instructor took charge of melting the metal.) Each student removed their flask from the kiln, set up the vacuum on the flask, poured the molten metal, removed the vacuum, removed the flask for further cooling, and quenched the flask and cast object. It was, again, slightly frightening to go through the process, and I over-filled my flask, getting metal onto the vacuum chamber (oops.) The excess, I poured into ingots for re-use.

Here are the bronze chunks I chose to cast with. Starting to melt the bronze. Heating, heating, heating... It really took a long time to melt, I have to say. Nearly there. My flask is ready on the vacuum, and the metal is ready to pour. About to pour... I've just overfilled (you can see a blob of molten bronze on the vacuum machine.) Pouring the excess into ingot-depressions carved into a charcoal block. The molten top is actually borax glass, from the flux used in the crucible. So I kindof singed the paint on the vacuum... Still hot, still under vacuum. Cooled enough to remove to a heat brick, for further cooling.

So how did it come out? Well…

Here's my succulent casting, freshly out of the investment (with a lot of cleaning yet to go...) Another view of the fresh casting. Yet another view.
Here I've cleaned it off a bit better, though there's more work to be done. Another view. The spiky leaves are quite sharp! ...sharpness demonstrated by my already having a bandaid on.

The texture cast perfectly, as far as I’m concerned. There’s still a lot to clean up — there’s lots of tiny crevices where investment is lurking — but the zebra plant leaves are sharp and amazingly textured, and the gollum jade leaves are plump and weird-looking. There were a few minor issues with shrinkage and porosity (since the piece couldn’t be vacuumed after the investment was poured in, not every bubble was dislodged), but over all, I’m pretty happy! I need to have someone cut off the bottom to flatten it out (right now it wobbles like a Weeble), so it’ll sit properly.

One bonus to casting this piece in bronze is that I can patina it, using any number of wonderful recipes. Since you can only do so much with sterling, and I don’t really work in other metals that patina well (like copper, or bronze), it’s an exciting prospect!

Thanks again for following along! More posts (with actual, finished, non-class-related jewelry) coming soon.