Quote:
Originally Posted by bob47
The first glasses I wore were American Optical plano tempered glass safety glasses. They seemed easier to clean and stayed clean longer than today's plastic lenses. Is that just my imagination?
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Not your imagination. The anti-scratch coating seems to attract grease and dirt on plastic lenses. Not to mention the glass lenses didn't scratch nearly as much. The old photo-gray glass was much nicer color than the plastic Transitions lenses.
I worked in an eyeglass lab for about 7 years. Hated making the glass lenses. They chipped and cracked pretty easily before we heat treated them and then about 1/4 of them would crack in the heat treating machine. IIRC they would go in a super heated salt solution overnight, about 1700 degrees or something crazy like that. Oh and I just remembered, we had to do a "drop ball" test on the lenses after heat treating. Drop a steel ball down a tube of a certain length onto the lens to make sure it could take the impact. Some of those broke too. We pushed plastic lenses, needless to say.