From the attached press release: "Brainstorming by engineering economists at Armour Research Foundation of Illinois Institute of Technology... Show moreFrom the attached press release: "Brainstorming by engineering economists at Armour Research Foundation of Illinois Institute of Technology uncovered methods of grafting clay raw material to reduce particle size of limestone and eliminate surface popping, or "spelling." This machine is used in a spooner's plant to mix clay and water, remove air from mixture, and extrude clay in cylindrical form." Photographer unknown. Date of photograph unknown. Date range listed is approximate. Show less
