Forward to the Field

Through the years the IWCA and the Glass Committee have been very dedicated in their pioneering efforts to educate and support our Window Cleaning Community/Industry.  The benefits of membership include the immediate benefits of the  practical  information uncovered by true scientific research.  Which has recently risen to a much higher level as the GC has partnered with the Penn State Material Sciences Lab and Professor Seong Kim and his team, and the Glass Association of North America (GANA).  The research work of the Glass Committee is also being supported by Dr. Paul Duffer through his in house research at his personal lab. He has been a tremendous source of help to the IWCA for decades.  We truly do appreciate all of his selfless efforts.  The IWCA has very recently become a collaborator in a grant with the National Science Foundation (NSF) for studying scratched glass cases.  There are also other things going on now which are quite historic.  Future generations of Window Cleaners will remember these events as being a pivotal turning point in our industry.  Paul West has done an outstanding job at establishing these relationships.  Now it is our turn to support the IWCA by joining and working in the field to provide the essential information and materials needed to further the research that we will all benefit from.  Because true scientific research is a never ending journey;...not a destination!  The GC is very hard at work in learning about exactly what all the conditions are that promote scratched glass.  Along with especially finding ways that we can minimize or even eliminate it.  This is what these above mentioned organizations that the GC has partnered with are very intently interested in. 


I think we can all testify to the fact that not all Glass is of the same smoothness, and that rough glass can be scratched much easier.  This has been observed in the field for decades.  Lets then begin this discussion by making the statement that "processing debris created during manufacturing" is in fact a component that can scratch glass.  Particles that have the potential to scratch glass include processing debris such as glass dust, glass chips, and furnace insulation; particles commonly found in the natural environment -  airborne or waterborne sand & soil particles; as well as particles that accumulate on construction projects - concrete, stucco, sand, even certain paints which contain silica. In fact anything that is as hard as or harder than glass has the potential to scratch glass;... especially under the wrong circumstances.  Such as when the surface is rough (not smooth).  If the particle is hard enough and under enough pressure, it can create a point indent fracture (PIF).  Scratches almost always begin with a PIF.  Even if it is only a small PIF.  Another "wrong circumstance" or condition that Penn State discovered for us is how temperature and relative humidity (RF) can change the chemo-physical properties of soda lime (window) glass enough so that PIFs form much easier.  Further it is quite impossible to tell exactly what particle caused what PIF.  So taking a micrograph of the scratch with its PIF is not enough to identify the chemical nature of the particle that caused the PIF and hence the scratch.  It is also true that window glass surfaces are quite different from silica glass.  For this reason they are much more prone to PIFs at the right temp and RH.  This is owing to the placement of calcium and in particular sodium atoms in and around the silicon and oxygens. 

Tempered Glass Properties

Check out the drawing here that I created showing the arrangement of the different atoms in the builder/moderator matrix of soda lime glass.  The little blue dots represent the oxygen atoms, the little yellow dots represent the silicon atoms, the medium sized green dots represent sodium atoms, and the large red dots represent calcium atoms.  Another interesting fact is that certain micro-crystalline surface growths can be initiated by various hydro-thermal reactions.  Further if you google glass degradation, which is otherwise known as weathering,  you will pull up some fascinating micrographs of chemically altered glass surfaces.  The primary molecule involved in this reaction being nothing more than water!  It is very important to watch the extent of the cycles of water condensation and evaporation on glass during storage before installation.  It has been noted too on bottle glass (which is also soda/lime), that various types of "bloom" will form under said conditions of condensation and evaporation.  It was through the research of the Glass Committee that it was learned that the process of weathering can be substantially cut back by the simple application of a quality hydrophobic glass sealant, and then maintained. All that is required is a single molecule.  That is all that is needed to block or form a barrier to the chemical attack of water. 


The very simple fact here is that there are various sundry conditions that if present will seriously increase the potential for scratching.  It is these conditions that the IWCA GC is looking to scientifically identify. Regarding this we can help greatly by providing from the field accurate documentation of glass that is prone to scratches.  Paul West has put together a questionare that we can all fill out and send back to him.  This will help us all as we continue on this journey.  So, “To the Field”!  


Scratched glass questionnaire: What is the address/location of the property? Who is the manufacturer of the scratched glass? How many levels/floors on the property? What levels did the scratching occur? Did the scratching occur on interior or exterior or both? Describe the interior surroundings near any scratched glass. Describe the exterior facade and surroundings near any scratched glass. Was there any accumulation of debris and  sand/soil on glass? How was the debris removed? Was the scratched glass annealed, heat strengthened, or tempered? Is the glass coated or uncoated? Where is the coating located; surface #1, #2, #3 or #4? Is there an insurance claim, lawsuit, or loss of money involved? Is it the tin side or airside of glass that is scratched? Was this a postconstruction cleaning incident or a normal maintenance project? What was the approximate size of the units involved? Did you observe that some glass units exhibited scratches while others in the same environment did not? Who initially discovered the scratched glass? 

Please fill out answers and return to:   

Paul West/IWCA Glass Committee

  Henry Grover Jr. Member IWCA Glass Committee 
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