What have we learned in the past 23 years? 

By Tom Trinen

In the late 1990s, one of the IWCA’s initiatives beyond safety was the costs window cleaners faced surrounding scratched glass lawsuits and disputes.

Just as technology in computing has advanced tremendously in the past 23 years, so has glass manufacturing and coatings technology.  A vast amount of tempered and heat-strengthened glass is installed in the residential and commercial markets annually in remodeling and new construction.

As glass products and coatings continue to evolve, building designs get more sophisticated, and the advent of mandated hurricane glass, all contribute to an increasing market of more expensive architectural glass: all more prone to scratching and expensive to replace.

 In the early days of the IWCA, self-proclaimed glass experts developed the concept that hypothetically, inconsistencies in quality control during the tempering process produced small fused defects that, when scrapped, were dislodged, causing scratching.   The defects were described as “glass fines,” and the phrase was coined.  Microscopic review seemed to support this theory.

This theory came possibly from the end game, that window cleaners needed a believable defense when they found themselves in the middle of a scratched glass lawsuit.  Thanks to the IWCA and social networks, this universal problem now had a universal, industry-wide defense for WC companies to rely on when threatened with a suit.

As word spread throughout the industry, window cleaners still suffered through lawsuits.  Without “Care, Custody and Control” insurance, it was unfortunate, but many went out of business when they couldn’t afford to pay out of pocket on lawsuits they were not insured to defend. 

Whatever the cause of a “glass fine,” the fact is that tempered and heat-strengthened glass is inherently different from annealed glass. Tempering and heat-strengthened glass use high heat, and due to a slow, controlled cooling, the reaction gives the glass safe breakage characteristics. As the center of the glass cools, it tries to pull back from the outer surfaces. As a result, the center remains in tension, and the outer surfaces go into compression, which gives the tempered glass its strength. Glass in tension breaks about five times more easily than it does in compression, and such stresses cause the glass, when broken, to shatter into small pieces.

As in any industry, glass manufacturing has challenges self-regulating the good quality from poor-quality tempering players.  Unfortunately, this blame game certainly wasn’t popular with the glass manufacturers in the tempering industry and created a wide gap in the stakeholder’s relationship. It was 1999, and window cleaners blaming the glass manufacturers for scratches they caused was not the best path to building a collaborative and harmonious relationship.

In 2000, the IWCA’s early discussions with the Glass Association of North America (GANA), and a glass expert, Dr. Paul Duffer, began.  In 2001, as Past President of the IWCA, I was tasked with industrial relations, and with a meeting in Baltimore, we tried to open peace talks.  As IWCA’s Past President and chair of the glass committee, Paul West helped initiate research-based studies.  

The IWCA’s relationship with the Glass Association became collaborative, resulting in a series of bulletins including “Construction Site Protection and Maintenance of Architectural Glass,” “Tempered Glass Products Are Different,” and updates to their Do and Don’ts in “Proper Procedures for Cleaning Architectural Glass Products.”  

Fast forward to 2015.  Even though the glass fine explanation seemed plausible, we needed it backed by science. IWCA commissioned a series of technical studies, first through Dr. Duffer and later through a study done by Penn State.  Thanks to the passion and persistence of Paul West, he helped drive the efforts to get funding for these technical studies. Guided by Dr.  Paul Duffer, the IWCA provided funding for a study program at Penn State University. Professor Seong Kim directed the Penn study using a Scanning Electron Microscope (SEM).

What did we learn?  

The research showed that it was nearly impossible to re-create the fusing of glass particles in a tempering oven.  The concept of “glass fines” and “Fabricating debris” was challenged by science.

The Penn studies describe tempered glass microscopically as a crystallized condition. At a microscopic level, glass and scratches are crystalline; by nature, crystals grow on crystals.  The concept that a scratch grows over a relatively short period of time after it occurs was a breakthrough.  

The Bulletins have also drawn attention to risk avoidance. Paul West believes “The window cleaning industry is now better positioned to educate general contractors, property managers and homeowners on the proper care of the glass. This includes proper storage, protection during all phases of construction, and initial cleaning techniques. In doing so, we protect the integrity of the glass surface.”

What has not changed is the use of large metal scrapers in the hands of untrained cleaners will still scratch; whatever the cause, it’s hard to argue that the glass was defective before it was scratched by removing debris.

The IWCA’s recently published and regularly updated Field Guide for Professional Window Cleaners has a tremendous amount of information on the subject.

Smart window cleaners will understand it’s still a balancing act that requires in-depth training and educating clients, general contractors, and employees if they’re going to avoid all potential scratches.