The new designs, of which I’ve shown the waxes in recent posts, have been cast in sterling silver to become the masters from which I will make the vulcanized rubber production molds. It is always such a relief to see that translation securely made… many disasters can befall this process.
Ordinarily the foundry would saw off the conical buttons from the sprue, that connecting rod, which was the channel that allowed the molten metal to flow into the “waste-mold”, made by pouring plaster around the wax inside a cylindrical stainless steel flask. That flask is put into a kiln to melt out the wax, thus effectively destroying my carving! The work, however, is temporarily retained as a negative cavity inside the plaster. There is only one opportunity to replace it with metal… hence the term ‘lost wax casting”…
When the process fails I am required to start all over again on a new wax!
The buttons in this position demonstrate how their weight helps push metal into all the details & furnish a reservoir while the metal shrinks during cooling. Being the last to solidify, that mass takes the stress & distortion inherent in the changing states from liquid to solid. They will be replaced later with smooth buttons for the molding process…
As we look into the interiors of the bells, anticipating the sounds they might make when relieved of all the extra weight in the buttons & sprues, we can enjoy the show of fiery visuals involved in the moments of the actual casting process. These photos show James, proprietor of OutCast & Company, during a pour for a vacuum cast.
After bringing the metal to melting temperature inside the blast furnace, one sees him taking the flask out of the oven with tongs & placing it on the vacuum table . The crucible is then lifted out to pour fiery metal into the cavity of the plaster mold flask while the vacuum draws the air out ahead of its passage to prevent loss of detail & encouraging a dense casting.
THE MOMENT OF TRUTH!
All looks good, but one never knows until the flask is broken open to reveal the result. A period of glowing meditation &/or nervous anticipation is required while the last of the flame keeps the button molten until the interior metal has safely solidified…
I leave you with the knowlege that the process was successful since you saw the masters at the top of this post. Next I will polish the masters & make the molds, hopefully taking time to make photographs to continue sharing these technical aspects of my work.
Being a Double Leo explains my joy in such fire!
