Scientific Characterization of Coloration Pigments and Deterioration Diagnosis on the Surface for the Gilt-bronze Seated Bodhisattva at Cheongyang Unjangam Hermitage, Korea

Abstract

The gilt-bronze seated Bodhisattva in Unjangam hermitage is known as an artifact of the 14th century. The main deteriorations of the statue are cracks, peeling and exfoliation in gold-gilding layers and coloration pigments. This is a factor that not only degrades aesthetics but can also cause additional damages. Ultrasonic velocity of the statue was mean 2,140 m/sec, showing low physical properties at the lowest part of the left and right sides. Surface on the body and coronal of the statue was gold gilding and colorfully colored by pigments. In the statue, Ti and Ca are highly detected in bottom pigment layers. This is affected by shell whitewash and modern titanium white, and the black pigment seems to have been used for black ink. In red, components of iron oxides, copper oxide and Pb<sub>3</sub>O<sub>4</sub> were detected. Blue is considered as patina, and green pigments are divided into green and dark green depending on the saturation, and containing Cr<sub>2</sub>O<sub>4</sub> and CaCO<sub>3</sub> as the main components were used. The surface on the statue uses Cu-bearing gold and modern synthetic pigments, the overall color is dull and it does not match the formality and era. Therefore, it is necessary to repair it according to the production period and original form based on historical studies.