verb sap - eyeglass coatings and hot work

Greetings and salutations
I am currently employed as a "injection press operator". This means that some times I spend a shift inserting bolts into a mold so that
the plastic part has them imbedded. Every 75 to 83 seconds I lean into the machine and insert six bolts. Weeeee. (It beats working.)
However, I have discovered a small, but very annoying problem. Heat. Injection molds tend to be rather warm (170 degrees F and up) and after eight hours of doing this, the protective coating on my (new) lenses "wrinkles". The effect is ... well my glasses never get clean. There is always this "smudge".
This had not happen with the old pair, just the new pair. I took them back to the eyeglass place, and the technician observed that my lenses were a tad small, so they are going back to be replaced. That is the good news. The bad news is - they will still 'fry' when exposed to radiant heat. Not just hot molds. This is apparently a hazard of fireplaces, ovens, and other radiant heat sources. Yippie. One would think that forty years of material science development, yadya, yada ... we would have a better option than glass for lenses for those who work around hot stuff. But, apparently we don't.
Unless, someone has a "better idea". Would safety goggles worn over the glasses protect them? The clear (or colored) plastic overshields which we wear to keep 'stuff' out of our eyes.     Does anyone know?
Are there coatings which do not melt when you open and stare into an oven?
tschus pyotr
p.s. The reason that the old pair didn't have the problem is that the coatings have pretty much worn off.     -- pyotr filipivich. Discussing the decline in the US's tech edge, James Niccol once wrote "It used to be that the USA was pretty good at producing stuff teenaged boys could lose a finger or two playing with."    
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On Wed, 24 Dec 2014 08:45:17 -0800, pyotr filipivich

First answer -- no, I don't know. But on the guess that no one else does, either, here are a couple of thoughts:
Most lens coatings are metal oxides. Those are fairly refractory, and I doubt if they wrinkle. What's probably "wrinkling" is the bond interface with the lenses. They probably have much different thermal coefficients of expansion, and the bond may be failing in shear with the heat.
Second, plycarbonate safety glasses block IR pretty well, but not UV. If it's just heat that's radiating, then you need UV blockage.
This is pure guesswork, but the ideal might be one of the certified laser safety glasses or goggles. They block specific wavelengths, but a little research and some data:
http://www.thorlabs.com/newgrouppage9.cfm?objectgroup_idv2
...may get you there. That, and some more info from others who might respond.
If the radiation itself is not a problem for your eyes, you might just want a cheaper, uncoated pair of backup glasses.
Good luck! And remember, this is all guesswork on my part.
--
Ed Huntress

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wrote:

There's no UV unless it's white hot: http://en.wikipedia.org/wiki/File:Black_body.svg
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On Wed, 24 Dec 2014 12:38:46 -0500, "Jim Wilkins"

Jeez. I got the IR and UV reversed. Sorry about that. Brain fart.
Polycarbonate blocks ultraviolet, but not infrared. It's useless for the injection-molding application. Radiant heat is mostly infrared.
--
Ed Huntress

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wrote:

Since I have polycarbonate safety glasses and a hot wood stove I checked. The skin around my eyes feels -much- more heat without the glasses, and an IR thermometer reads only 120F through them. They may have a scratch resistant coating but they aren't tinted at all. -jsw
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I'm not risking my eyeglasses any further to answer a question.
At the distance where the heat from the glowing charcoal is intolerable without protection in about 2 seconds, I can't feel any heat through Harbor Freight polycarbonate safety glasses #94357 with sheet metal held above and below. Unlike my eyeglasses they are wide enough to block heat around the sides. -jsw
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On Wed, 24 Dec 2014 08:45:17 -0800, pyotr filipivich wrote:

If they don't (and from what Ed says about polycarbonate, once he got sorted out) they don't, then there may be a material that's transparent in the visible and reflective or absorbtive in IR that you can add to the mix (I typed UV first -- thanks Ed).
Check http://www.edmundoptics.com/ (used to be Edmund Scientific). If god is smiling on you then they'll have some sheets of stuff you can just stick onto your face shield.
Also Google around and see if you can find a table of transmittances by material -- if you can find something that's clear in the visible and absorbtive in the IR, and that doesn't give an OSHA inspector colonic spasms, then you're in.
--
www.wescottdesign.com

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How do we know that it's the coating, versus the lens material? If it's a safety lens, it will be polycarbonate, which melts at a fairly low temperature, and is very sensitive to solvents and solvent fumes.
In any event, of all the plastics used for eyeglasses, CR-39 is by far the most resistant. <http://en.wikipedia.org/wiki/CR-39
This is what I use.
Joe Gwinn
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typed in rec.crafts.metalworking the following:

    That seems to be the consensus, at least online.

    Thanks.

-- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
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On Wed, 24 Dec 2014 08:45:17 -0800, pyotr filipivich

Glass or polycarbonate lens? What coatings? There are numerous manufacturers and types of coatings for both glass and polycarbonate lens, and non-coated glass lens are also still readilly available.
I'd have 2 pairs of glasses - uncoated glass work glasses and coated glass or polycarbonate glasses for other use.
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snipped-for-privacy@snyder.on.ca on Wed, 24 Dec 2014 15:11:24 -0500 typed in rec.crafts.metalworking the following:

    PC and the new High Refractions Index lenses.

    And which ones are the most stable when exposed to radiant heat? The sort which comes off hot molds, out of ovens or fireplaces?

    That it what it appears I am going to be doing.
    And looking for a job where it is not a problem. -- pyotr filipivich "With Age comes Wisdom. Although more often, Age travels alone."
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