The choice of refractory powders or grains, binders an additives affect the properties of investment casting shell. Different systems of shells were made, according to a design of experiments, using commercially available raw materials that differ in chemistry, particle size or particle size distribution. The strength of the shells was measured in green, fired and cooled, and hot conditions and the results are analyzed for strenght-material property relation.

In addition to the material property, shell building parameters also affect the strength of the shell by changing the relative amounts of stucco, slurry and porosity over the cross section. Various microstructures of polished cross sections of shells have been characterized for microstructure-strength relations.