A study is made of mechanical properties of unglazed matrix as a funtion of sintering temperature and crack patterns in layer structur pottery consisting of glaze and substrate and in matrix which is sintered at 120$0^{circ}C$ and 130$0^{circ}C$ respectively. The mechanical properties of matrix are increased due to density and vitrification to 130$0^{circ}C$ The interface of glazed bilayer reveals the reactive intermediate layer. Herzian indentation testing is used to investigate the evolution of damage modes as a function of load. In the materials sintered at 120$0^{circ}C$ quasi-plastic deformation is developed at the matrix and the cone-like cracks initiate at the glazing top surface and additionally upward-extending transverse cracks initiate at the internal in-just initiate at the glazing top surface which pass through the interface with increasing of indentation load. Finally the dominant damage mode shifts from substrate quasi-plasticity to coating fracture with increasing sintering temperature.