Cleaning glass: A many-faceted issue

Stephen P. Koob

Abstract

The removal of decades of cigarette smoke, grease and grime from handling, and more recently, pollution and off-gassing from improper storage cabinets, will contribute significantly to the prolonged stability of all glasses. In addition, glasses that are subjected to prolonged storage in high humidity (over 55% RH) will begin to hydrate and the alkali in the glass is brought to the surface. Unless this is removed, the alkali will eventually start to dissolve the silica in the glass.

There are numerous types of glasses, but the “silica-soda-lime” glasses make up approximately 90% of all types from antiquity to the present, from Roman vessels to modern window panes. These glasses are generally thought to be very stable, but they will slowly deteriorate (through weeping or crizzling) over decades and centuries of prolonged exposure to high humidity, grime and pollution.

Most glasses can be washed using a detergent and water, as long as the glass is sound and in good condition. Warm tap water can be used for the initial washing, followed by rinsing with deionized or distilled water. A dilute conservation-grade detergent is recommended, such as Synperonic A-7 or Triton XL-80N. Cleaners or detergents that contain perfumes or ammonia should be avoided. A simple washing, even once in the lifetime of a glass, will protect the glass for decades, if not centuries. Soft brushes and soft cotton toweling are recommended. Glass objects should never cleaned in a dishwasher, or with abrasive sponges or cleaners.

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