AIC's 52nd Annual Meeting

Three basalt sculptures by the South Korean Artist Byong Hoon Choi called “Scholar’s Way” were installed in a pool of water, outside the new Kinder building for Modern and Contemporary art, at the Museum of Fine Arts, Houston in 2020. The sculptures are carved from naturally occurring columns of basalt sourced from Indonesia, with most of the surface being highly polished to a black mirror-like finish. Parts of the sculptures around the bases and at projecting elbows of the abstract forms retain a weathering crust. Before the installation, conservation had concerns about what effect the surrounding environment and the addition of chemicals, to control the water quality, would have on the sculptures. In a short time, the polished surface had dulled and granules of the crust were falling off. Although the artist has worked with this material for 40 years, only a few of his sculptures are installed outside in water. Despite his assurance about the material durability we obviously had a problem whose mechanisms needed to be more fully understood. Conservation collaborated with students and faculty at Rice University to determine the geochemistry of the basalt and weathering crust, as well as to analyze the water quality and its chemical composition. Surface measurements of the columns with near infra-red, energy dispersive spectroscopy (EDS) and electron probe microanalysis (EPMA) showed that the base rock that was used was already in a highly altered condition before installation. The degree of alteration on the surface was accelerated by weathering in humid conditions. The weathering crust is largely made up of clay and some remnant basaltic igneous minerals. The EPMA showed that the basalt contains orthopyroxene, Ti-augite, plagioclase, and Ti-magnetite and is thus an iron-titanium basalt. Secondary minerals are widespread and make up more than 90% of the crust. These minerals are mainly clays such as ferripyrophyllite, ferrisepiolite, and kaolinite. The presence of these minerals proves that the rock was altered by hydrothermal processes prior to human intervention. The effect of weathering in humid conditions affects the surface of the rock. The porous clay aggregate readily absorbs water and the other remnant minerals are somewhat soluble in the chemically treated water. The civil ordinance governing water features which had been used to justify the use of harsh chloride containing bleach and acid in the water was deemed inapplicable to this non-interactive feature. The clay minerals occur over the entire surface of the sculpture including previously polished portions, consistent with recent weathering in addition to the original weathering crust. This study is ongoing. A protective wax has been applied to the polished areas. We have not decided on whether a consolidation treatment can be applied to the weathering crust as this may cause greater damage. We are removing the additive acid/alkali mix from the water and are investigating replacement with a copper salt to prevent algae growth.