Due to the hazards involved with this process, all work is to be done in a qualified lab or similar art studio setting. Extra caution should be taken during ceramic shell formation, burn-out, and pouring of molten bronze (forging). Respirators, fire suits, fire tongs, gloves, leather boots, and eyeware are required in combinations.
Next, the pieces are sprayed lightly with hairspray or fixitive. This provides a microscopic coat of bumps the dip can better cling to. The piece is alternately dipped in a fixative mix (I will add the mixture later), then into a fine silicone sand. The piece is allowed to dry for at least 30 minutes, hanging from the hook of the pour cup. A fan is added to speed this process. After two layers of the fine coat, a coarser silicone sand is used to build up the shell from ¼ to ½ inch thick. The layering process is repeated with variation until enough coats are built up to provide an ample ceramic shell. It is important to wear your respirator during the ceramic dipping, silicone dust builds up in your lungs over a lifetime and can lead to serious health problems. Eye protection is also important, because the dip can splatter into your eyes.
One pour cup held 3 long keys, the other 4 the shorter keys. This would allow me two keys to decide against in the future. Once the pour cups have been thouroughly attached, some vents need to be incorporated. The purpose of the vents is to allow air in the mould to escape during the pour, because bubbling through the molten bronze will cause uneven cooling, leading to a weak project, possibly incomplete with voids in the design. The vents should run from the lowest point of the mould to the top of the pour cup. Too many vents is much better than one too few.
I had an idea for my project that came to me in a dream. I saw five keys, one spinning on each finger on my hand. The concentration required to keep them all balanced was very intense. I started with some sketches, then modeled them from the wax. I found the wax to be very easy to manipulate. In fact, it was difficult to keep my fingerprints from appearing on the soft surface at times. Keeping the wax refridgerated when it is idle keeps the piece from deforming from the heat of room temperature. Some choose to use a woodburner or soldering iron to speed the modeling process when working with larger sculptures. When the keys were to my liking, I realized that they required an extention to be later cut off to attach them to the pour cups.
After the shell has reached thickness, a final dip without sand, after allowed to dry, is brushed with a couple of coats of a curing solution (more on this later too).
It is now fired in an electric kiln to hardened the ceramic shell. The bronze is heated in a gas kiln, and poured from a crucible with teamwork and fire protection. After several hours of cooling, the ceramic shell can be beaten off with a hammer. Wear your respirator and use caution while removing the shell, you can bend and dent your piece. The remaining vents and remnants of the pour cups can be cut or ground off, and the piece polished with a polishing wheel, steel wool, or polishing compound with cloth. Patinas (such as shoe polish) can be applied. Mount your piece on an appropriate base if need be. I wanted a mixed-media piece, bronze combined with ceramics.
