An experiment for the development of weather-resistant urushi lacquer applied on wooden buildings (2) [Original title and text in Japanese]

Urushi lacquer coating technique has been applied on wooden buildings for centuries. Even now it is used to restore urushi lacquer layers. However, urushi lacquer layer is very sensitive to ultra violet rays. Therefore, it is very difficult to conserve urushi lacquer layer in an outdoor environment where it is exposed to sunlight. In this case, maintenance by frequent re-coating is required. Our department has aimed to evaluate new materials which last longer than urushi lacquer and do not require frequent maintenance. In this report, we present our attempt trial to strengthen the fondation and the coating film by using different combinations of carbon fibre, jisu-urushi (denatured polyurethane paint: Saito Co., Ltd.). and natural urushi lacquer. As a result, we found that the adhesion between natural urushi and carbon fibre is not so good and that the coating film of jisu-urushi is not as thick as that of natural urushi. So we trial-applied an improved version of this new coating material to Takabutai, Itsukushima Shrine.