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

在日本，许多带有珍珠或珍珠母的装饰文物已经存活了数千年。它们中的大多数是由于长期暴露在各种环境条件下而恶化的。笔者尝试对这些材料以及玉翅工艺品进行保护性研究。为了弄清这些材料的劣化状态，进行了以下科学调查：1）调查适当的调查方法，2）用强氙灯加速老化试验玉慕翼，3）调查和分析罗马珍珠的劣化。对珍珠的荧光性质、软骨藻素、文石晶体堆结构、晶体溶解、碳酸钙晶型变化、无机成分的研究方法进行了综述。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，材料的颜色变化不大，材料由数千层螺旋状的甲壳素层组成，结构对其颜色有影响。根据这些分析结果，证明珍珠是由一种淡水Pelecypod产生的。然而，长期的存放使珍珠逐渐严重变质，珍珠层部分破碎，容易脱落。有机膜附着力的降低是导致其劣化的直接原因，其主要原因是贝壳蛋白的分解。

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.