ABSTRACT

Tarnishing is one of the most crucial issues in the conservation of silver alloy objects. This phenomenon is relevant in the field of cultural heritage artifacts: although the blackish patina protects to a degree against ulterior corrosion effects, it significantly affects the aesthetical features of the artwork. Several different approaches are utilized for cleaning tarnished silver–copper alloy surfaces, including mechanical, chemical, electrochemical methods. The use of lasers is also reported. In this paper a dry approach based on the use of erasers is proposed and compared with traditional methods. The different methods were applied on silver–copper alloy mockups which had been artificially tarnished. They were compared based on the degree of sulfide removal and damage to the silver surface. Diagnostic investigations showed that the use of erasers for silver cleaning resulted in fewer surface modifications compared to traditional mechanical methods with an effective tarnish removal. The proposed method could be broadly considered a low-cost, adjustable, and fast one-step cleaning procedure. Finally, two case studies of application of the technique are reported: cleaning of three Islamic artifacts decorated with silver alloy inlay and of the silver letters on the North Door of the Baptistery of Florence.

摘要

失去光泽是银合金物品保护中最关键的问题之一。这种现象与文化遗产文物领域有关：虽然黑色的铜绿在一定程度上可以防止受到不可告人的腐蚀影响，但它显着影响了艺术品的美学特征。几种不同的方法用于清洁失去光泽的银铜合金表面，包括机械、化学、电化学方法。还报道了激光的使用。本文提出了一种基于使用橡皮擦的干法方法，并与传统方法进行了比较。不同的方法应用于已被人为玷污的银铜合金模型。根据硫化物去除程度和对银表面的损坏程度对它们进行比较。诊断调查表明，与具有有效去除锈蚀的传统机械方法相比，使用橡皮擦进行银清洁的表面改性较少。所提出的方法可以广泛地被认为是一种低成本、可调节和快速的一步清洁程序。最后，报告了该技术应用的两个案例研究：清洁三件饰有银合金镶嵌物的伊斯兰文物和佛罗伦萨洗礼堂北门上的银色字母。