In article ,
wrote:

On Thu, 17 Apr 2014 07:09:36 -0700 (PDT),
wrote:

On Wednesday, April 16, 2014 10:20:39 AM UTC-5, wrote:
I need some new glasses, so I went to Zenni............However



I want bifocals with a polycarbonate lens. And Zenni does not do bifocals
in Polycarbonate. And they say their polycarbonate lens are not OSHA
approved. I tried to get what material they use so I could look up the
specs. but I couldn't get that info from them.



So does anyone know of a good place to get bifocals in a material that is
OSHA approved? Or at least material that comes close to being OSHA
approved.



Dan

I haven't used them, but I found this:
http://www.safetyglassesusa.com/safreadglas.html
Glass?
Depends what you are trying to protect against. Flying grit od squash
balls.

Yeah, glass.

When I was a four-eyed kid in the 1950s, I had all manner of mechanical
hobbies. My Father's reaction was to get me industrial safety lenses,
which were made of tempered glass with a 2mm or 3mm minimum thickness
in the center.

I never broke a lens, and there were events where a broken lens was a
possibility.

I eventually ran across the standard for safety hard lenses - it should
withstand a 16-ounce steel ball dropped one foot into the face of the
lens.

So I tested the lenses form an old pair of glasses: dropped a 16 ounce
hammer head onto the lens, which was sitting convex side up on a piece
of wood. It took something like a 15" drop to break the lens, which
turned into glass crumbs.

So that's why I never managed to break one in service.

Joe Gwinn