Lost Wax Casting: Carved Stone Ring

Here's my first completely independent project that I made at home in prep for my casting class. I was under the gun to get something ready to create a plaster mold of so I looked up various designs online for inspiration. I didn't want to choose anything too difficult since I'm lacking in tools at home and I thought there was a lot of forgiveness in this design. If I screwed up a crack here or there, well who could tell anyway right?

I was nervous to make my first casting since it's a fine balance between the water and investment powder that needs to go into the mixture.  In the burnout stage of the casting process the wax model is melted away and I certainly didn't want to lose my wax model for nothing.  Luckily the mixture was just right and I was able to melt down 20 grams of sterling silver for this ring.


The ring itself is roughly 13.5 grams of silver (pretty heavy for your finger) but the added silver was required to account for the sprue (wax branch that creates the channel to inject molten silver) and for shrinkage.

I heated the silver beads using a large torch after they were added to a container in the centrifuge, and once the silver became molten the torch was removed and the lid of the centrifuge was immediately closed, triggering the motor to start. The spinning process was about 2 minutes.

After letting the plaster mold and casted silver piece cool for another 6 minutes the cannister was plunged into a bucket of water and swirled around dissolving the plaster. I retrieved the oxidized ring which was a gunmetal grey and threw it in the pickle solution (sulfuric acid). After about 10 minutes and some scrubbing with baking soda it came out gleaming white from the thin layer of pure silver coating the surface.

 I was surprised how much the material looked like plaster rather than silver but was told that a little light polishing would get rid of the the fine silver and reveal the familiar colour just below the surface.  I sawed off the sprue and filed down the ring to smooth out the edge.  I'll wait until next week to start the polishing.

Carved stone ring with fine-silver coating