Comparison of the Characteristics of Baekak(chalk) and Hobun(shell) Pigment for Dancheong based on Natural Raw Materials

Abstract

Calcium carbonate white pigments were manufactured by classifying them into Baekak(chalk) and Hobun(Shell) according to the type of natural raw material, and their material characteristics were analyzed. Their performances were compared by evaluating their weather resistance, antifungal activity, and flame retardancy. The main components of Baekak pigments are calcite and dolomite, and those of Hobun pigments a re calcite and a ragonite. Depending on the raw material, the specific factors identified are Mg from the mineral composition of Baekak pigments, and P and S from the protein composition of Hobun pigments. The particle shape of the pigment shows a crystal structure unique to minerals in the case of Baekak pigments, but the Hobun pigments are classified into plate-shaped or columnar structures depending on the raw material and are in an aggregated state with a large specific surface area. While the absorption amount of Baekak pigments made from limestone and dolomite is similar, that of Hobun pigments shows differences depending on the raw material, with the absorption amount being high in the order of oyster > cockle > clam. As a result of the color analysis, both the Baekak and the Hobun pigments had L* values of over 90 and opacity of over 90, indicating good whiteness and painting workability. As a result of the accelerated weathering test, the final color difference value(ΔE) was less than 2.02, which was difficult to recognize with the naked eye, and the Hobun pigment showed superior color and film stability compared to the Baekak pigment. As a result of the antifungal test, all calcium carbonate-based white pigments showed high preventive effects against decay fungi, and among them, the pigment made from clams and cockles showed excellent antiseptic properties. In addition, the pigment made from clams and cockles has been shown to have flame retardant properties, and it is expected that it will contribute to enhancing the preservation of organic cultural heritage when applied to it.