Quick test for Pyrex or plastic

[brightnorm]

I have a quick test I use to determine if a lens is Pyrex or plastic. It works beautifully but most people will probably hate it. I take the tiny point of a very sharp small Fiskars scissors, place it at the outer edge of the lens, angle it slightly and press lightly in the direction of that angle. You can instantly tell if it sticks or doesn't, and the mark is invisible to all but the most thorough search.

Brightnorm

 

[Doug Owen]

You can do the same sort of test (steel against the material) with a knife blade on the edge of the lens as well. No chance of a mark.

Doug Owen

 

[Connor]

You can also "feel" it. Put your light in the fridge for a while or outside the house.

Glass "feels" much colder than plastics. No need to poke holes into it with a knife. ;-)

-Connor

 

[Kiessling]

You could also ask the members of CPF ... /ubbthreads/images/graemlins/grin.gif
bernhard

 

[kongfuchicken]

Or read the box...

 

[Zackerty]

Has anyone considered that you might create a stress riser in the lens, so that whatever it is made of, might crack when dropped accidently!
I have done some tests with Lexan, and the edges have to be smooth, otherewise any stress risers will come and bite you later! I can tear 1mm sheet with my hands with a single knife cut in the edge! Bit of force required, but it can be done.
Putting pin pricks into it, might possibly cause the aforementioned stress risers... any ideas?

 

[Robban]

[ QUOTE ]
kongfuchicken said:
Or read the box...

[/ QUOTE ]
Yeah that's what I was thinking. No offence here but it seems rather retarded to deliberately scratch a lens to find out info that no doubt can be had from the packaging, manufacturers website, CPF or the internet in general.

 

[brightnorm]

Well, as I said, people will hate it (or assume the loss of some cerebral neurons) but I've done this for several years, dropped and bounced lights, so far with no discernable ill effects. However, a word to the wise is always appreciated and carefully listened to.

BN

 

[GarageBoy]

Pyrex has a feel.. no need to scratch

 

[Unicorn]

Glass also has more of a tink sound when tapped with a peice of metal than any plastic has.

 

[sotto]

I picked this trick up from my wife who has made quite a lot of beaded jewelry. (Note: this particular test may not be practical depending on the size of the flashlight lens.) First, for example's sake, take a regular glass tumbler (you know, the kind you drink out of) and tap it lightly against your front teeth. Notice the sound you hear and the tactile feedback you get through your teeth. Next, take a plastic drinking glass and do the same thing.

Now, by tapping a flashlight lens against your front teeth, you should be able to readily identify whether the lens is plastic or pyrex.

 

[JonSidneyB]

Take a close look and let your eye focus really well. You are going to be looking for some rather fine detail. See if you can find any carbon based molecules. If you see carbon based molecules its plastic.

 

[GarageBoy]

Yes and glass is SiO2 with something added to it ::wink

 

[JonSidneyB]

you need really good eyesight to do this.

 

[udaman]

[ QUOTE ]
JonSidneyB said:
Take a close look and let your eye focus really well. You are going to be looking for some rather fine detail. See if you can find any carbon based molecules. If you see carbon based molecules its plastic.

[/ QUOTE ]

LMAO, JSB's either had too much rest, sleep, and fude over the holiday weekend; or has been deprived of all of the above /ubbthreads/images/graemlins/wink.gif

With my really bad eyesight, LOL, I'm squinting to look at JSB's avatar...can't really tell, but appears to be carbon based life form /ubbthreads/images/graemlins/crackup.gif . So....plastic? (udaman puts foot in mouth again /ubbthreads/images/graemlins/grin.gif) /ubbthreads/images/graemlins/ohgeez.gif /ubbthreads/images/graemlins/twakfl.gif /ubbthreads/images/graemlins/twakfl.gif /ubbthreads/images/graemlins/twakfl.gif

 

[JonSidneyB]

I will tell her that....lol

 

[Topper]

I gave it a try. Still checking but I think if your carefull you can get the mark of Zorro on the wall or even the Bat signal. Jokes aside some of mine I thought were glass (i cant spell pyrex)turned out plastic. one off a Z2 was actually melted in the center?? I may go for the Mark of ZORRO with that one. Glad I bought a couple Turboheads and have spares laying around.
Topper /ubbthreads/images/graemlins/smile.gif

 

[greenLED]

[ QUOTE ]
Unicorn said:
Glass also has more of a tink sound when tapped with a peice of metal than any plastic has.

[/ QUOTE ]
That's how I tell them apart.

 

[AuroraLite]

[ QUOTE ]
greenLED said:
[ QUOTE ]
Unicorn said:
Glass also has more of a tink sound when tapped with a peice of metal than any plastic has.

[/ QUOTE ]
That's how I tell them apart.

[/ QUOTE ]

Same here...but then

[ QUOTE ]
sotto said:
I picked this trick up from my wife who has made quite a lot of beaded jewelry. (Note: this particular test may not be practical depending on the size of the flashlight lens.) First, for example's sake, take a regular glass tumbler (you know, the kind you drink out of) and tap it lightly against your front teeth. Notice the sound you hear and the tactile feedback you get through your teeth. Next, take a plastic drinking glass and do the same thing.

Now, by tapping a flashlight lens against your front teeth, you should be able to readily identify whether the lens is plastic or pyrex.

[/ QUOTE ]

That's how I swallow my first Solitaire... /ubbthreads/images/graemlins/icon15.gif