For thirty years now window cleaning professionals have blamed such defective glass surfaces on what they have called glass fines. In other words the glass dust that is routinely released at the end of the float line when plate after plate of glass is scored and broken. The float line almost never stops! It has become routine to let it go for many months and sometimes years before the line is stopped for cleaning. Because of this dust and other contaminants every plate of glass must be properly washed before it is heated again for tempering. It also must be scored and cut again to the correct size before tempering. Tempered glass cannot be cut. The idea has always been that when float glass is heated again, any glass dust (fines) would fuse to the surface and be driven into it by the tempering rollers, if the glass were not hung vertically but rather passed horizontally on ceramic rollers. All very logical. Right? But.
If such "glass fines" were from the glass plates, then shouldn't they have the same exact elements in the same exact proportion as the glass they came from? It is my understanding that a spectrographic analysis was performed and a readout of the atomic elements was produced. Which did NOT match glass at the factory where the fines came from. In fact there was a very high level of aluminum that made absolutely no sense if you were to accept the first theory explained at the beginning of this post. You see window glass only has a very small amount of aluminum present anyhow. So how do we figure out exactly what such roughness or particles are? Where do we go from here?
As a famous physicist once said you simply have to look at the animal! I try to look at things as much as I can. And ask questions that to me seem obvious. We must get the questions right of course. Because getting the question right is at least half of the solution. Nonetheless our first encounter with a defective/scratch sensitive surface is not sight;... but sound. In fact none of us has likely ever really seen a particle. We have all heard them however. As we drag our razor blades over them in soapy water. What we learn from the sound is that each defective glass surface is different. But since the process of scoring and breaking is always the same, why would the dust be made of different sized particles and in different amounts? The sound is always quite characteristic/different. Telling us that the particles can be large, small, or even microscopic. Also telling us that there can be millions or only hundreds spread out over the glass.
The closest we have ever really got is to look at the scratches that result from dragging a razor over the glass. The goal here would be to look at such scratches using a quality handheld lighted microscope. I have had good success so far with a handheld lighted 40X magnification microscope. If nothing else these scratches will tell us the size of the particles in question. Once we know that we could focus our microscopes on the particles. Here I would ask questions like what is the shape of each? Do they show a different colored reflection? Are they in some fashion lodged in the glass surface? Also there are likely more interesting questions we could ask. But above everything else by actually LOOKING at the animal we should come up with some very pertinent conclusions. Also we should come up with some truly fascinating questions that will take us deeper down and guide us in discovering greater truths about the real answers to just what these mysterious "ghost particles" really are.
So stay with me here as I dig deeper down in revealing some truths which we can use in our quest for more reasonable answers. Of course even if we know exactly what the ghost particle really is, it is not going to just vanish. They will still be out there in abundance on almost every building. They will continue to be created and end up on new glass. Further we will have to work with this problem or walk away from windows that have them. The glass industry is of course much larger than the window cleaning industry measured by the dollar bill. So this problem will never go away. It is here to stay. We will just have to contend with it as is.
Written by Henry Grover Jr.