Weld Splatter and Abrasion
Splatter from welding can cause permanent surface damage. Weld splatter and general scratching from heavy abrasion can reduce glass strength and lead to breakages. When welding is taking place or abrasive processes carried out in close proximity to glass, heavy screening must be erected to protect the glass.
Condensation
When condensation forms and then dries repeatedly
on
a glass surface, it is possible that the surface may
become stained.
Moisture can leach alkali materials from glass, and evaporation can then concentrate the alkali solution, often forming water spots or runs on the glass surface. These can be hard to detect in certain lighting conditions and may prove difficult to remove.
Measures should be taken to reduce the degree of condensation that forms. Appropriate ventilation or the installation of insulating glass units will reduce the likelihood of condensation repeatedly occurring.
In cases of light damage it may be possible to remove the marks by polishing with cerium oxide. Some special products of a weak acid formulation are also available. The use of such agents is a skilled procedure and not all commercial cleaners are experienced in their application.
Iridescence
Iridescence is a greasy or oily film on the glass and in many cases this effect results from leaching of alkali bearing substances.
When iridescence involves large areas of glass, the only practical remedy is replacement. When relatively small areas are concerned, it can sometimes be removed by polishing with cerium oxide.
9.11 Glass
Cleaning and
Maintenance
Architectural glass products must be properly cleaned during the construction period so visual and aesthetic clarity are maintained. Because glass can be permanently damaged if improperly cleaned, glass producers and fabricators recommend strict compliance with the following procedures.
First, determine whether the glass is clear, tinted or reflective. Surface damage is more noticeable on reflective glass compared with the other glass products. If the reflective coated surface is exposed, either on the exterior or interior, special care must be taken when cleaning, as scratches can result in coating removal and a visible change in light transmittance. Cleaning tinted and reflective glass in direct sunlight should be avoided. Cleaning should begin at the top of the building and continue to the lower levels.
Commence cleaning by soaking the glass surfaces with clean water and a soap solution to loosen dirt or debris. Then, using a mild, non-abrasive commercial window washing solution, uniformly apply the solution to the glass surfaces with a non-abrasive applicator and follow with a squeegee to remove all of the cleaning solution from the glass surface.
Ensure that no metal parts of the cleaning equipment touch the glass surface and that no abrasive particles are trapped between the glass and the cleaning materials. All water and cleaning solution residue should be dried from the window gaskets, sealants and frames. Refer Section 14.20 and 14.21.
Scratches and Metal Scrapers
Scratches can occur from hard pointed objects or poor handling, but most often occurs from the careless removal of foreign matter from the glass surface.
Mortar splatter and paint are common offenders and efforts to remove after hardening almost always lead to surface damage. It is essential that the foreign materials are removed before they harden. Better still, if construction work continues after glazing, that the glazed areas are protected by adhesive plastic films or suitable tarpaulins or covers.
One of the common mistakes made by non-glass trades people, including glass cleaning contractors, is the use of razor blades or other metal scrapers on a large portion of the glass surface. Using large blades to scrape a window clean carries considerable risk of causing damage to the glass.
The glass industry, fabricators, distributors and installers neither condones nor recommends any scraping of glass surfaces with metal blades or knives. Such scraping usually permanently damages or scratches the glass surfaces. When paint or other construction materials cannot be removed with normal cleaning procedures, a new 25mm razor blade may have to be used. The razor blade should be used on small spots only. Cleaning should be done in one direction only. Never scrape in a back and forth motion as this could trap particles under the blade that could scratch the glass.
Blades or scrapers can dislodge “pickup” on
toughened
glass. There are fine particles of glass that are fused on to
the surface during toughening. Once dislodged they can scratch the
glass.
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To
the right hand side of each performance diagram is a swatch showing a photographic
sample of the glass.
Visible
Light Transmission
Visible
Light Reflection 
Ultraviolet
Elimination 
Fading
Reduction Coefficient 
Solar
Heat Gain Coefficient 
Shading
Coefficient 
Window
Efficiency Rating System 
U
Value 
Coolness
Factor 
R
Value (Total Thermal Resistance) 
Sound
Transmission Loss 
Sound
Transmission Class 
Weighted
Sound Reduction Index 
Perceived
Sound Reduction