building a Polariscope

Most people i know already have LCD screens.
and quite a few old laptops are hanging around waiting to be salvaged.

That's good news for us and bad news to Polariscope manufacturers...
Just get hold of an old laptop LCD screen to get the filter from,
and the rest is a piece of cake.

(the older the LCD screen is - the better.
in new ones the filter will be glued on,
and i have yet to find a way to remove it when it is glued without ruining it.
if you know how to do it - let me know!)

NOTE: Polariscope will show you stress in CLEAR glass.
if you want to check a batch of anealed COLOURED beads-
make an extra CLEAR bead from the same glass you are using, to aneal with your beads, and check that CLEAR bead to learn what the rest are like.
it should be the size of the others, since glass-thickness
will determine the schedule for your annealing.

Category:

Howto & Style

Tags:

• polariscope
• polarize
• stress
• glass
• glassblowing
• lampwork
• borosilicate
• boro
• pyrex
• polarimeter
• polariser
• polarizer
• stressmeter
• light
• aneal
• anneal
• פולריסקופ
• פולרימטר
• פולאריסקופ
• פולארימטר
• israel

[BongMcPuffin]

Does this only work only on clear glass? Or can I use it on a heavily colored and worked tube sculpture that you can't see through using normal light?

[catman72]

@BongMcPuffin alas - only clear glass :-(



[Tamooj]

This is a great DIY polariscope, but I just use my iphone (or laptop monitor) with a white image and a pair of ordinary polarized sunglasses. You can clearly see the stress lines in this manner, and it's very portable. For dark or colored glass you can use a higher intensity light source - I put a camera filter (polarizer) over a high intensity mag-light style flashlight. If the glass is completely opaque (not just darker or colored) this obviously won't work.

[catman72]

@Tamooj - i used to do it with my old Treo , but my current Motorola Milestone

has a different kind of screen. Apparently many new screens have non-linear polarizers,

or maybe no polarizers at all. so i had a few embarracing moments trying to show

the effect in several places, with some screens that simply did not cooperate...

doing it with a small screen and polarized glasses is great when you're out shopping

for glass items, and want to know how well they were made. :-)

[catman72]

@Tamooj (cont.) using a pair of polarized glasses will force you to tilt your head sideways

because the angle of the screen polarizer is about 45 degrees, and you need to be at 90 degrees to it,

so you do it with your neck, or hold the glasses in your hand for it.

i find both ways not comfortable. i prefer holding the glass with both hands, and concentrate

looking at it.

[folkertdekens]

sweet and simple thing for quick inspection of my processed polycarbonate pieces, I will make item this week thanks for sharing (catpeople are nice people I dare say) good luck with your inventions, folkert.

[catman72]

@rocboy2006

seems perfectly good.

i can only suggest re-checking annealling tables for your specific glass,

and perhaps a longer soaking time and longer ramp-down?

make test pieces of any colour you have + your clear base-glass, and

anneal and check in a polariscope for any incomaptibilities.

that's all i can say.

ask Acroduster if he has any good idea.

[catman72]

@rocboy2006

as far as i know- no way to check dark coloured glass.

how can you tell that "...that section does not seem to be stressed hard as other parts"?

if you anneal according to the right tables for your type of glass (time as function of thickness)

you should be OK, unless you have comaptibility issues between your

glass colours, because of different manufacturers.

did you have any breakage ?

[rocboy2006]

@catman72

Sorry I have to write a separate reply due to youtube's word limit. By the way, I did a temperature shock experiment in which I freeze the bongs in my household freezer around -10C for 30 mins before taking them out and letting them warm up in room temperature about 20C. They didn't break. I am not sure if that is sufficient to conclude that they were annealed.

[rocboy2006]

@catman72 Thanks for your advice. Some of glass bongs I received do have a clear section, but that section does not seem to be stressed hard as other parts, so I can't really tell the stress for colored by checking only on the clear section.

They are made of borosilicate glass, size is about 4mm thickness, 500mm in length. Is there other way to check if they are annealed?