1mm thick U-glass, a visual test

[Cadmium]

How to tell the difference between 1mm thick versions of UG11, U-340, and ZWB1 using most common light bulbs.

NOTE: I have not tried this with household LED light bulbs yet, just with compact fluorescent and incandescent bulbs.

WARNING: This is a VISUAL test, so DO NOT perform this test with the sun or other bulbs that may contain strong UV content.

If you have a GG420 or similar yellow longpass filter to suppress UV, then you should use that also as I have below, but don't do this with the sun or stronger bulbs either.

PLEASE limit this visual test to common compact fluorescent or incandescent bulbs, and I recommend using a 420nm longpass filter to block any UV content that even a common bulb might have.

 

Take your U-glass, hold it up to view your light bulb stacked with your BG glass (BG40, S8612, BG39...) and 420nm longpass (UV suppression).

Simply put, you *should* see nothing when stacked with BG glass.

UG11 will show no visible light. U-340 and ZWB1 will show some light.

Again, this test will only work using 1mm thick glass (except ZWB1, which will even show light at 1.5mm thick)

 

This light is not UV, because I have stacked GG420 to remove any light lower than 400/420nm.

This light is in the 500nm range, more specifically peaking in the 540nm to 580nm range (ZWB1 extends slightly higher is seems also), because I have stacked various longpass filters with these and isolated the visual leak in that range.

No BG glass, such as S8612, BG40, BG39 will suppress this range of visual light.

If your U+BG stack is adequately suppressing IR, then you should not see anything if you stack a 600nm range (or higher) IR long pass filter with your U+BG stack, because this visual leak is in the mid 500nm range.

 

If you have 1mm thick U glass and you can see light through it from a light bulb when stacked with BG/S8612..., then it is most probably not UG11.

It will not matter how much BG/S8612 glass thickness you use, the thicker the better for this test, but using U-340 or ZWB1 will still show the light. UG11 will not.

 

Conclusion: Although all of these glass types look to have similar visual transmission graphs, they are not the same.

There is a visual leak in the mid 500nm range that people need to be aware of and test for when using thinner glass.

This is an easy test. It will not work with thicker U glass, except it is still visible with ZWB1 1.5mm thick.

I will try to show this photographically soon, but you may want to try this visually.