Monday, January 16, 2012

Fused Glass Pendants - How to Shape and Fire Polish

With 500 pendants in progress, I thought I'd talk about one of the finishing techniques.

After the fused glass has been kiln cast in "bricks", sliced on the tile saw, and fused again with a layer of dichroic glass, they are finally ready to be shaped, grooved and polished.

The pendant on the left is "before" shaping/grooving the pendant on the right is "after" shaping/grooving.


Can you see the narrow groove/channel that runs along the edge of the pendant in the side view? That is there to hold the sterling silver wire in place when the piece wire wrapped.

I recently bought a Glastar All-Star G8 grinder and have been very happy with it. The grinding bit on the left that is just sitting on the top is the one I use to shape the pendants. The bit that's on the grinder head is called a jewelry bit, and it's how I put that groove into the edge of the pendants.

All that grinding and shaping leaves the edges rough and cloudy. Pendants are too small to be cold-worked with progressively finer sandpapers, so I fire polish them.

Here's a blurb from the Warm Glass website that explains fire polishing: "Fire polishing is the simple technique of returning glass items to the kiln to melt them just enough to give a smooth, polished appearance. It typically takes place at a temperature that ranges from 1300 F/700 C to 1400 F/760 C."

I've mentioned before that I fuse all my glass in a ceramics kiln. Here they are loaded into Gladys, my Skutt glaze-tech test kiln.  

Here's the four segment firing schedule I use to fire polish:

Segment 1: 500 deg. F/hour to 1000 deg. F and hold for 10 minutes
Segment 2: 500 deg. F/hour to 1275 deg. F and hold for 10 minutes

Segment 3: 9999* to 1025 deg. F and hold for 15 minutes

Segment 4: 9999* to 975 deg. F and hold for 10 minutes

(*9999 is how I program the controller on my kiln to cool as fast as possible. Some kilns will say "full" instead. Just check your owner's manual if you aren't sure.)

Below is a shot that shows what the pendants look like pre-fire polish and post-fire polish. The pendant on the left is still rough and cloudy from shaping. The sides of the pendant on the right are all smooth and glossy again after fire polishing. Hooray!

Now they're ready to be wrapped in wire. Stay tuned for a video detailing how I wire wrap a pendant.


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