Volume 39, Issue 10,
Learning About Glass in Unconventional Ways
by Dez Farnady
Ever since I can remember, maybe even since the Egyptians first kicked the fire into the sand and it came out Graylite #14, I have been explaining the differences between one kind of glass and another to people.
At the height of my glass career, my personal collection of factory labeled 4- by 6-inch glass samples contained every known glass color, thickness and type made by the three major manufacturers of commercial glass products in the United States. I also accumulated some 30 or so boxes of 8- by 8-inch labeled factory samples. I owned, in my professional capacity, a virtual treasure trove of glass samples. Whenever a customer needed a sample, presto, I had it in my greasy little hands.
Having It All
I also had the goodies to back it all up. I had in my possession at least ten years of consecutive volumes of every glass company documentation or catalogue to provide the manufacturers data covering every sample I possessed. I could show you the differences and the documentation among every product on the market and quote light transmission and shading coefficient, just like I knew what I was talking about.
One thing had never occurred to me. You canít really tell what any of them actually look like in the opening by the documentation or a 4- by 4-inch or 8- by 8-inch or even a 12- by 12- inch sample. I had all the stuff and it was up to others to decide. The old trick was to dazzle them with stuff and document it all so that they could make a decision out of their confusion. Once they decided, it was their problem. It was just an old trick for an old dog. They say you canít teach them new ones anyway.
Well, maybe they can. I no longer need to be the glass expert, and whatever I still know is just residue. I no longer have the need to know, or the time to really keep up with, all all new products, but on occasion I still need to be able to explain the differences. One day, a colleague at work suggested that we put several different kinds of glass in one of the skylights in our shop. Well, that certainly sounded like a new trick to this old dog.
Within a few days we had replaced an old wired glass skylight with a new five-panel unit. Each panel was about 24 by 48 inches and was glazed with a different type of glass. Starting from right to left, the first panel was clear glass, the second panel was low-E2 followed by a bronze unit. Panel number four was glazed with evergreen and panel five was glazed with clear over white lami.
So, you might ask, what is the big deal? Well, have you tried it? Have you been there and have you seen it? If you had you might sing a different tune. This is no laboratory. This is the real deal. Did you know that under certain light conditions the low-E looks like the clear glass and if you did not know what it was you would call me a liar? When the San Francisco ďmarine layerĒ rolls in, that low-E can turn nearly as green as Solex, but not quite as green as the evergreen.
When the sun shines bright in the middle of the day the five different pieces of glass leave four distinct footprints on the floor below. No, that is not a typo. The five panels leave four footprints. You can see the distinct difference between the clear and the low-E. The low-E is a shade darker, confirming the documented difference in light transmission. The bronze and the green show their color on the ground and the white shows nothing. Thatís right, it shows nothing.
While the inside surface of the white laminated glass is brighter than the other four, it does its job to diffuse the light and spreads it out, leaving no spot of light on the floor. The experiment is interesting and the customers can see the difference. Since I am no dummy we just put in another one with five more very different types of glass. But thatís it. I have no intention of turning our roof into another sample collection. n
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