The western style assembly hall which was built in 1883, and is considered important cultural property in Japan, has three central ornaments made of stucco on the ceiling. Soot was removed by brushing with a mixture of alumina powder and an aqueous solution of CMC containing nonionic detergent. The brittle priming and the rims were reinforced with a fiberglass-reinforced epoxy resin. Missing parts and cracks were filled with <i>Primal AC 34 mixed with microballoon of soda-lime glass. -- AATA