Conservation Scientific Studies on Pearls and Mother-of-pearl Works

在日本，许多用珍珠或珍珠母制成的装饰品已经保存了数千年。它们中的大多数由于长期暴露在各种环境条件下而变质。笔者尝试对这些材料以及竹翅工艺品进行保护研究。为了明确这些材料的变质状况，进行了以下科学调查：1)研究适当的调查方法；2)对tamamusi -wing进行了强氙灯加速老化试验；3)对变质的罗马珍珠进行了调查和分析。对荧光性质、chonchiolin、文石晶体堆的结构、晶体的溶解、碳酸钙晶体形态的变化、珍珠的无机成分等进行了调查研究。不幸的是，从调查中发现了新的知识。加速老化试验结果表明，材料的颜色略有变化，材料由数千个螺旋堆积的几丁质层组成，认为这种结构对其颜色有影响。根据这些分析结果，这些珍珠被证明是由一种淡水准足类动物产生的。然而，由于长期存放，珍珠逐渐变质严重，珠层部分破碎，容易剥落。有机膜的附着力下降，主要是由于孔雀碱的分解，是变质的直接原因。

In Japan, many decorative artifacts with pearls or mother-of-pearls have been survived through thousands of years. The majority of them are deteriorated because they have been exposed to various environmental conditions for a long time. The author tried the conservation study for these materials as well as Tamamushi-wing (Chrysocuroa fulgidissima) crafts. To clarify the deteriorated states of these materials the following scientific investigations were carried out : 1) surveying appropriate investigation methods, 2) accelerated aging test with the intense Xenon-light for Tamamushi-wing, 3) investigation and analysis for the deteriorated Roman pearls. The survey for investigation methods was carried out for the nature of fluorescence, chonchiolin, the structure of aragonite crystal stacks, the solution of the crystals, the change of crystal form of calcium carbonate, and the inorganic components of pearls. Unfortunately, new knowledge from the survey was found out. The results of the accelerated aging test showed that the color of the material was changed slightly, The material is consisted of thousands of spiral stacks of chitin layer, and the structure is considered to be affected to its color. From the results of these analyses the pearls were proved to have been produced by a species of freshwater pelecypod. However, long-term storage had gradually brought about such severe deterioration of the pearls that the nacre is partially fragmented and easily peeled off. The decrease in adhesive power of the organic membrane, due mainly to the decomposition of conchiolin, is a direct cause of the deterioration.