Cleaning Pitfalls for Museum Niello
修复：博物馆乌银藏品的清洗禁忌
标签：乌银修复, 清洗禁忌, 硫化银, 大英博物馆
乌银（硫化银铜复盐）对清洗剂极敏感：氨水与硫代硫酸盐会溶解乌银填料（历史上多件中世纪圣物匣因用银饰抛光液而失去全部黑色纹线）。大英博物馆现行做法：先紫外荧光与 XRF 区分乌银区与银基底 → 乌银区仅用去离子水棉签滚洗 + 硅藻土软膏机械清洁 → 氯化银增生的银区单独用碳酸氢钠糊处理。对已脱落乌银不做熔补，只记录并存档硅胶翻模，遵循可再处理原则。
Niello (a silver-copper sulphide) is easily dissolved: ammonia and thiosulphate polish have stripped entire niello designs from medieval reliquaries. The British Museum now maps niello vs silver by UV fluorescence and XRF, rolls nielloed zones clean with deionised water swabs and diatomite paste only, and treats silver-corrosion zones separately with sodium bicarbonate paste. Lost niello is never refilled—only documented with silicone moulds, honouring retreatability. ---