It is essential that all external glass is thoroughly washed with clean water to eliminate all abrasive and chemical laden dust. Excess glazing compounds and sealants should be carefully removed from the glass and frame surrounds, taking care not to scratch the finished surfaces with tools or abrasives. A solvent (such as white spirit or professional glass cleaner) may be used to remove any glazing compound, finger marks or grease. The glass should then be cleaned as normal (see below). Frequent washing is required whilst construction continues on site, since chemicals in dust and particularly in cement may be activated by rain and cause permanent corrosion of the glass surface.
Use a mild liquid detergent solution then rinse the glass well with clean water and dry off. Under no circumstances may abrasive cleaning products or contaminated cloths be used. If rainwater coming from cement mortar contaminates the surface of the glass, frequent cleaning is necessary to prevent permanent staining. See also section on finishes.