Updated September 2009

Post construction window cleaning involves some of the

most difficult challenges in the window cleaning industry today.

Although most builders do make an attempt to protect

windows during construction, many fail to accomplish this

goal, leaving the window cleaner to deal with how to best

remove construction debris (plaster, paint, texture, concrete,

tape, stickers) and anything else that come into contact with

the glass.

Construction window cleaners already realize this type of

window cleaning is very challenging, with special training and

cleaning techniques being required to safely remove construction

debris from glass. This type of window cleaning often includes

the use of razor blades and glass scrapers, and at times

specialized soaps, chemicals and solvents.

It is well known by construction window cleaners that razor

blades and glass scrapers alone will not scratch uncoated

glass when properly used; the use of such tools has been

the industry standard for decades. Razor blades and scrapers

have been employed by not just the window cleaning industry,

but are also widely used throughout the glass

industry.

In recent years, as a result of contaminated or defective surfaces

on some tempered and heat-strengthened glass, construction

window cleaners have been exposed to new challenges

and unforeseen liability in construction window

cleaning. When standard construction window cleaning

techniques are employed to clean the contaminated or

defective surfaces on poor quality tempered or heatstrengthened

glass, scratching of the glass surface can and

very often does result.

Regular annealed glass is tempered or heatstrengthened

through a specific heating process in order

to provide certain safety characteristics. Prior to the heating

process, the glass is sized and belt-sanded to the desired

edge finish. If the glass is not then properly washed prior to

upon which the glass rides are not kept clean, microscopic

glass fines and chips resulting from the sizing and beltsanding

will become fused to the surface of the heat-treated

glass. These small particles will then cause fine scratches

on the surface of the glass when standard construction window

cleaning procedures are employed.

The glass washer, furnace and general fabricating plant

must be kept in proper working order or poor quality products

will result. This is a quality issue when fabricating heattreated

glass, not a window cleaning technique issue. Glass

scratching, as a result of fabricating debris, has since become

a quality, liability and client dissatisfaction issue.

Images of razor blade

before and after use on Defective Tempered Glass

Builders can help resolve this issue by requiring glass and

window suppliers to provide only quality heat-treated glass

to their projects that can be cleaned using industry standard

window cleaning techniques. Builders should only hire qualified

construction window cleaners to remove limited

amounts of construction debris from their windows.

Protecting windows during construction is always good

practice, but will not protect the future owner from a defective

glass product when it does require the window cleaner

to use a scraper sometime in the future.

Builders should also recognize the difference between fabricating

debris scratches and other types of scratches caused

by careless plasters, painters, texture crews and untrained

workers attempting to remove construction debris from

glass. Fabricating debris scratching is only on heat-treated

glass and usually very wide spread, light in nature and

mostly visible with direct sunlight.

Testing should be done prior to installation. You cannot always

detect fabricating debris with these simple tests, but

the scratching on the glass it creates is unmistakable. A

magnifier can be used to aid in the identification of fabricating

debris scratching, with scratches looking like a comet.

Fabricating debris magnified

While it may be possible to locate fabricating debris on

some heat-treated glass, window cleaners should not accept

responsibility for identifying fabricating debris or its’ absence.

For this reason, window cleaners should always require

a liability waiver, signed by the builder, releasing the

window cleaner from any liability for scratching on any tempered

or heat-strengthened glass. Builders would also

benefit if they required their glass and window suppliers to

sign a liability waiver, prior to entering into a contract, to

help ensure the builder will get the quality product he’s purchased.

For additional information:

Fabrication Debris Awareness Committee

© 2006 Master Window Cleaners of America

Updated September 2009

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