Glass is a durable material when exposed to normal atmospheric conditions, but it does suffer some surface deterioration. One of the most aggressive elements in the atmosphere is water. An absorbed layer of water attacks the surface of glass, dissolving or releasing certain elements that cause the water to become alkaline. With repeated wetting and drying without washing, the dissolved matter will appear as a whitish scum. This reduces the brilliance of the surface and in severe conditions can obscure visibility. This latter condition is common where condensation is permitted to occur regularly. Consequently, frequent cleaning is important.
Glass can be cleaned with warm soapy water, vinegar-based cleaners or any cleaning product specifically formulated for glass. Avoid using ammonia or alcohol-based cleaners, which can cause streaking. Care should be taken not to damage glazing, frame finish, or insulating unit seals by overgenerous application of cleaners. Wipe the cleaning solutions on the glass in a circular motion, applying light to moderate pressure. If streaks appear, rinse the surface with clean water. Using a clean, lint-free cloth, wipe dry the interior glazing surfaces, including any interior frame or hardware components, to prevent spotting or water damage.
To clean grease, oil, tape adhesive, crayons or paint, apply a small amount of acetone (mineral spirits) to a cloth or towel and rub only the affected area. Repeat the cleaning steps listed above, if necessary. Glass should be cleaned starting at the top and systematically working down. This technique reduces the possibility of residue and cleaning solution rundown. Caution: Do not clean glass or frames while they are exposed to direct sunlight. Detergents and soap-based cleaners may dry prematurely and leave a hard-to-remove residue on the frame or glass surface.