[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]SAFETY -- tempered glass vs. Polycarbonate[/FONT]
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Q - [/FONT][FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]
Which material makes a safer lens? [/FONT]
[FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]A- [/FONT][FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]
Polycarbonate is MUCH safer than glass[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]The dive industry's safety standard for masks is woefully inferior to that required of $4 safety eyewear. Indeed most common plastic eyeglasses must meet higher standards![/FONT]
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Tempered glass is 5 times stronger than non-tempered glass. Glass has the advantage of resisting scratches because it is quite hard. But you can’t have it both ways -- tempered glass is hard but very brittle -- it breaks. ALL professional full-face masks and dive helmets use Polycarbonate (PC) lenses for increased diver safety.[/FONT]
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All above-water safety eyewear is made from Polycarbonate because PC is more than 150 times stronger than tempered glass when measuring impact resistance. PC is “ductile” – it bends but does not break. Bullet-resistant eye guards are made from PC, the most impact-resistant of all polymers.[/FONT]
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The test for high-impact safety eyewear (ANSI Z87.1-2003) --[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]A 1/4-inch diameter steel fired at up to 204 MPH, with no lens breakage allowed:[/FONT]
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-- Spectacle lenses: 102 MPH (150 ft./sec.)[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]-- Goggles: 170 MPH (250 ft./sec.)[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]-- Faceshields: 204 MPH (300 ft./sec.)[/FONT]
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In 1985, before excellent scratch-resistant coatings for PC were formulated for automotive headlights, the leading scuba equipment companies agreed among themselves -- for the first time -- to establish an industry-wide safety standard for dive masks. But the company representatives settled for a "voluntary standard" that does not have to be followed. This standard was published through the American National Standards Institute (ANSI). Manufacturers put these stickers on some masks -- NOT ALL GLASS MASKS ACTUALLY PASS THESE STANDARDS, DESPITE WHAT THE STICKER SAYS -- [/FONT]
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-- This lens exceeds the impact test requirements of the[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]-- American National Standard Z86.11-1985. Impact resistant[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]-- lenses can break or shatter and cause injury to the user[/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]-- if subjected to undue force or impact.[/FONT]
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The "Z86.11-1985" dive mask test -- [/FONT]
[FONT=Arial, Helvetica, Geneva, Swiss, SunSans-Regular]A 1-inch diameter steel ball dropped by gravity from 50-inches onto the lens, with no breakage of the lens.[/FONT]
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However, NO mask with "fused-glass" corners (which didn't exist in 1985) passes "Z86" when the steel ball is dropped onto the “fused” corner. Glass shards are broken off the corners, leaving razor-sharp edges, which contradicts Z86.[/FONT]
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Hard-coated PC lenses will scratch more easily vs. glass. But underwater, minor scratches are invisible as the refractive index of the PC lens and seawater are so close -- the water fills in the scratches, as it does for minor scratches on your plastic-faced gauges.[/FONT]
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HydroOptix PC lenses are not made or tested to meet high-impact safety eyewear standards and should not be used as such. In fact we use a PC alloy that sacrifices some impact-protection to make our lenses more scratch-resistant. All that said, our lenses are 10-times more impact-resistant vs. any recreational glass dive mask. A few divers have told us how our PC lens saved them from potential tragedy -- and had a severely scratched / gouged Double-Dome lens to prove their story. Our PC lenses are replaceable.[/FONT][FONT=Arial,Helvetica,Geneva,Swiss,SunSans-Regular]
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