ミャンマー産漆と日本産漆の塗膜硬さに閬する 定量的評価

摘要

Lacquer is extracted from three plants of the family Anacardiaceae, namely, Toxicodendron vernicifluum, Toxicodendron succedaneum and Gluta usitata. Toxicodendron vernicifluum is distributed throughout Japan, Korea and China, Toxicodendron succedaneum throughout Taiwan and Vietnam, and Gluta usitata throughout Myanmar and Thailand. Extracted lacquer is different for each species in material properties. For example, lacquer extracted in Japan forms dark brown coating film with unique texture, and lacquer extracted in Myanmar forms black coating film with gloss. The present study focuses on the properties, especially hardness, of Myanmar lacquer coating film. It is said that Myanmar lacquer coating film is softer than Japanese lacquer coating film, although this is hardly approached scientifically. Therefore, scratch test and nanoindentation test were conducted to evaluate the hardness of Myanmar and Japanese lacquer coating films. As a result of the tests, it was found that Myanmar film is easier to scratch and more elastic than Japanese film. These properties of Myanmar lacquer make it suitable for the technique unique to Myanmar, namely kinma in which a line is cut in the lacquer coating film for decoration with pigments. In addition, some lacquerware are made from horsetail hair and bamboo, and are soft. Even when this lacquerware changes shape under stress, lacquer coating film is not broken. In this way, Myanmar lacquer coating film is suitable from the aspect of technique and materials. Such knowledge would be useful for Myanmar lacquerware restoration.%日本産漆塗膜とミャンマー産漆塗膜について，ナノィンデンテーシヨン試験とスクラッチ試験を行い，硬さに関する試験を行った。試験の結果，ミャンマー産漆塗膜は日本産漆塗膜に比ベ，傷がつきやすく柔軟性に優れていることが示された。ミャンマー産漆塗膜の物性は，漆塗膜に線を刻む工程のある蒟醬技法や，指圧で容易に変形する馬毛胎漆器に適していると判明した。今回，硬さ評価を行ったことで，漆器修復を行っていく上で有用なデータを得ることができた。