Back-Up Slurries

Think about a toothpick and a 2 x 4. They will have the same MOR assuming they are made of the same kind of wood. However, you can not walk across a toothpick, it is too small in cross-section to support the load. The extra width and especially the added thickness of the 2x4 allow it to support a much greater load. The same is true of the thicker ceramic shell. As an example let us consider two ceramic systems one (A) with a modulus of 600 psi and (B) with a modulus of 400 psi. If 5 coats of shell system A have a thickness of 0.25 in. and 5 coats of shell system B have a thickness of 0.5 in. and we assume they both have the same width then the load bearing capacity will be in proportion the square of their thickness as follows  

The weaker (lower MOR), but thicker shell can support more than 2.5 times the load of the stronger, but thinner shell system. 

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