Glass or Plastic lenses: Which is better?

[Uncle Bob]

I've searched the forum but can't find any useful answer why one is better than the other. I suspect both can scratch. Glass can break. Plastic might melt. What am I missing here?

[Long John]

Here you can get some answers:

http://www.candlepowerforums.com/vb/...6577&highlight

Best regards

____
Tom

[sween1911]

I've searched the forum but can't find any useful answer why one is better than the other. I suspect both can scratch. Glass can break. Plastic might melt. What am I missing here?

The glass in a Surefire lens is lab-grade Pyrex, and it's pretty impact and heat resistant. They have been known to go south under some serious force application, but it's not common. The lexan lenses can get scratched up, but they're a bit lighter and more resistant to shattering than the Pyrex. There's some give and take with everything.

In short:

-Pyrex or the other high end glass lenses out there are REQUIRED for high powered lights that have enough power to melt a plastic or lexan lens in a matter of seconds. They are also scratch resistant. Glass's only downsides are slightly more weight, and subject to shattering under extreme impact.

-Lexan/polycarbonate/plastic is lighter and more impact resistant, but can be melted by a high-power light, or even a moderate power light (Surefire 6P for example) that is left on in an enclosed area (or bezel down) without the ability for air to move and cool it off.

There really is no "best", just what you need for the application.

Be aware, that's there's clear plain plastic lenses out there on cheap lights that are thin, easily scratched and not as impact resistant as real lexan/polycarbonate. On older lights, there is glass that is like window glass in the lens, so all the warnings on safety apply. Obviously clear, but prone to shattering.

[vic2367]

i think i read somewhere once that glass lens actually let more light through ,,,better than the plastic lens ,,

[Illum]

T
-Lexan/polycarbonate/plastic is lighter and more impact resistant, but can be melted by a high-power light, or even a moderate power light (Surefire 6P for example) that is left on in an enclosed area (or bezel down) without the ability for air to move and cool it off.

I have heard that leaving P60 LA on for the full duration of the battery life will cause the lexan to turn soft and warp if your not careful even in an open environment...but Surefire still use it on the G2/6P last I know

[MarNav1]

24 odds and ends on a table. Pick one up do you have an odd or an end?
Not being smart a.. but that's about how many opinions you'll get on this one. I personally don't care for plastic but other's do so there you go.

[sween1911]

I have heard that leaving P60 LA on for the full duration of the battery life will cause the lexan to turn soft and warp if your not careful even in an open environment...but Surefire still use it on the G2/6P last I know

The new 6P comes with the Pyrex lens, but I think G2 still has the Lexan lens.

[BlackDecker]

Another problem with plastic lens is that they do discolor with age turning somewhat opaque, allowing less light through the lens.

A look at any plastic automotive headlight from a car more than 3-4 years old would give you an idea.

[GregWormald]

And of course, to add to the complexity, some glass transmits more light that others, and adding anti-reflective coatings increases transmission. Some lenses have a-r coatings on one side, some on both. A-r coatings have also been applied to some plastics.
In general, I'd say that glass is more transparent, shatters easier, scratches harder, and is more heat resistant.
Greg

[Uncle Bob]

Another problem with plastic lens is that they do discolor with age turning somewhat opaque, allowing less light through the lens.

A look at any plastic automotive headlight from a car more than 3-4 years old would give you an idea.

Is it a matter of age or exposure to sunlight? My lights don't see much daylight. They're out at night.

[Illum]

Is it a matter of age or exposure to sunlight? My lights don't see much daylight. They're out at night.

could be both...I've always thought thats just dried impurities in the rain dried by the halogens as they always seemed brighter AFTER a car wash

[BlackDecker]

Is it a matter of age or exposure to sunlight? My lights don't see much daylight. They're out at night.

When plastic ages, it can yellow - whether or not exposed to UV rays. Exposure to heat or cold can cause it.

[LukeA]

Another problem with plastic lens is that they do discolor with age turning somewhat opaque, allowing less light through the lens.

A look at any plastic automotive headlight from a car more than 3-4 years old would give you an idea.

That's surface oxidation. You can take that off with Flitz or Brasso or any other soft metal polish. Plus it makes your car look newer.

[TORCH_BOY]

Glass of course

[Diesel_Bomber]

My brief experience:

All my lights had plastic lenses until recently, when I bought two MagChargers. I have used plastic lens equipped Mags in rough service for years and have not had a single failure. During absolutely normal usage I managed to break the glass lens in one of my MagChargers within two months of purchase. I don't know how the stock MagCharger glass lens compares to others for strength. I replaced the lens and I now carry a spare, but I'm not happy feeling I have to baby these lights. If there was a plastic lens available that would handle the heat I'd switch in a heartbeat.

YMMV.

[BSCOTT1504]

Glass....

[Flymo]

Recently I replaced the (glass) lenses of my Pentagonlights (L2 and X2) with a (AR coated) Ultra Clear Lens from http://www.flashlightlens.com and the results is noticeable.

[bigterk]

ACRYLITE Anti-Reflective sheet, a continuously
manufactured sheet, utilizes a wide band anti-reflection
coating that minimizes reflection while it maximizes the
transmission of the acrylic substrate over the visible light
spectrum. ACRYLITE Anti-Reflective sheet is designed
for the high performance needs of LCDs, PTVs, PDPs,
P-O-P displays, signage and much more.
Standard Product Off ering:
• Colorless
• Sizes: 41”x 71” – usable area 39” x 69”
(cut-to-size available upon request)
• Thicknesses: .080” (2mm), .118” (3mm)
• Anti-Reflective and Abrasion Resistant coating
on both sides
Tinted; single side coated; and other thicknesses are
available upon request. Minimums may apply.
Environment/Durability:
• Abrasion Resistance – 600 Cheesecloth
per Mil-M-13508C
• Adhesion – #610 Snap Tape per Mil-C-48497A
• Humidity Resistance – 48 hour (50°C, 95% R.H.)
per Mil-C 48497A
• Solubility – 24 hour immersion per Mil-C 48497A
Transmission
Front Surface Reflection
% Reflectance (Photopic)
• < 1.0% Single Surface
• < 2.0% Total Reflectance (Double Side Coated)
• < 5.0% Total Reflectance (Single Side Coated)
% Transmittance (Photopic)
• > 97.0% Total Transmittance

[jumpstat]

Definitely glass over plastic lenses, it better in the long run...

[entercpf]

I don't want to nitpick but, should be mineral glass, big difference imo

[JNewell]

I've been using SureFire lights for somewhere between 15-20 years and while I understand and can make the arguments for Lexan or similar materials, I don't buy them (the arguments...or the plastics). "Plastic" scratches, melts, yellows...glass is a better choice unless you have some ultra-specific need for a non-glass material.