Saturday, February 20, 2010

Lost Wax Casting

Lately, Heather and I have been doing a little bit of lost wax casting. We wanted to learn the process and possibly make some cool stuff.

Heather, carving the wax.

The first step is to carve wax. Blanks come in block, sheet, rod, and ring form which can all be combined to create any form you want. The ring form is a hollow tube that you first cut to length, then carve out to size, and finally shape to your desired form.

Two rings on their sprues.

Next is spruing the artwork so that the metal can flow to it from the top of the mold. This part breaks your heart because you basically ruin the final form, ensuring more finishing of the cast metal.

Fresh cast silver with sprues.

Next we cast the parts ourselves which was quite stressful. It is loud and fast, and if anything goes wrong, the parts will not cast properly. The metal is melted in a crucible, and poured into a plaster mold made from the wax. A vacuum sucks the metal down into all the fine details of the mold. After the metal cools a bit we put the plaster into water where it disintegrates and we were left with warm silver parts.

Cast ring filed and sanded, before polishing.

We then filed and sanded the parts up to 600 grit. Our rings were faceted meaning that we had a lot of surfaces to get right while trying to keep the edges crisp. At this stage the pieces had a nice brushed look.

The two rings, polished.

The final step is to polish the pieces. This is done with a polishing wheel, in this case on an industrial grade Dremel like tool. This is where the silver really starts to shine, and we wondered, should we have left it brushed?

Gem Nuggets!

These are hollowed out silver gems. They were carved by hand and then hollowed out with a Dremel. They will be put on a chain with some wood beads.

Winnipeg!

Heather made me a sweet silver map of Winnipeg! It will be stitched onto my bag or jacket soon.

All the pieces, bonding.

-Scott