Defective glass is very easy to scratch. But not as easy to identify. Simply because the scratches can be so small that they can only be seen in the direct sunlight at just the right angle. Or they can be so large that they can be seen at night with a dim flashlight. This is very simply because the size of the ghost particle is learned by the depth and size of the scratch. The number of ghost particles is also determined by the number of scratches per square inch or as I like to say the scratch density.
It is very easy to mistake frictive glass surfaces for defective surfaces. This is because defective particles can be so incredibly small. As small as nanometers. I have included here an example of 50 nanometer sized aluminum silicate particles.
Here is an example of just exactly the type of scratch I am talking about. These were created by a short four inch edged razor. I took the picture with my IPhone in the direct sun. Gotta love these phones and digital technology!
Frictive glass can be quite rough and yet show no scratches when a razor is used. I know this is counterintuitive but I have observed it. Then there exists defective glass with ghost particles so small that they feel like frictive glass but do in fact cause scratches from a razor. Now with this being said we should not get the idea that frictive glass is not totally safe. When we polish glass to remove hard water spots with a cerium oxide slurry we end up creating a frictive surface that will scratch much easier than most glass surfaces that feel very smooth with a penny.
Admittedly this discussion can be rather confusing. But i think all that is required is the reader to spend a few years cleaning glass for a few years to know that all glass is NOT the same. There is a great difference. Sometimes on the same plate! Just beware. Defective glass is more abundant now then it every was. And it is waiting to cause a lawsuit. You do not want to have to face such a thing. Your insurance will not cover it. And it could destroy your entire business.
Written by Henry Grover Jr.
henrygroverjr@gmail.com
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