C&A offers shale strength testing to help determine damage in strength to cores from fracturing fluids. The shale strength change method involves dynamic exposure of shale cores to the fracturing fluid at temperature, shear rates and times representative of the fracturing treatment. Shale strength changes are determined by measuring hardness of the core surface exposed to the fracturing fluid and comparing it to the opposite side of the core that was not exposed to fluids. The Brinell Hardness is calculated from the ball diameter, load applied, and diameter of the indention created.