Study of the aging of CaCO3 used on the restoration, and its manufacturing technique

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Investigation into raw materials and the making process of calcium carbonate be used for pigments, wall painting and plaster works is important for conservation and restoration of cultural properties. Limestone and shells are known as the calcium carbonate raw materials. It was known well that Ruditapes, Crassostea and Meretrix were written in literature and used in the plasterer.We discriminated limestone and shells used for calcium carbonate by the form with optical microscope and scanning electron microscope. The crushed shells have a unique form each other and showed different form from it of limestone. After calcination, the form of limestone and shells remained the crushed form with porous structure on the surface. The size of vacancies of limestone was extremely smaller than that of shells. Although the slaked and carbonated limestone remained its form, the form of shells is fragile and became powder. The results indicated that the distinction of limestone and shell is possible … More by the form of particle. It is possible to know that the raw material of CaCO_3 is shell or stone, even shell's type. We focused the differences of biomineral growth of shells, and tried to make a chart for distinguish each shell. The chart is easy to use with microscope. Furthermore, the compound of calcinated particle is epitaxially growth and the shape of shell structure is kept after calcination. The shape of shell has a lot vacancy, become fragile. In limestone, it has more hardness than the shell. We can know the particle was calcinated or not. It is clear that observation with microscope produce more information than instrumental analysis.On the other hand, we also observed the form of these materials after exposure test in outside and in inside. As a result, we can know a kind of the original materials although the transparency and the coarse on surface were different from control.Finally we established the method how to know the original materials and the condition of deterioration of cultural properties using CaCO3. Less