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UV blocking power of polycarbonate



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#1 Damon

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Posted 30 November 2014 - 06:13

I recently obtained a UV meter so I could make sure I was not exposing myself to too much UV while hanging around with my Blak-Rays. Apparently Andrea doesn't want anybody to have brown spots and wrinkles when they get older, so I decided to look into it a little deeper.

Awhile back I asked if it was ok to just use any old plastic goggles to protect my eyes and was informed that polycarbonate, be it expensive or dirt cheap would completely block UV. Just as long as it was actually genuine polycarbonate. Although it was recommended to buy a known brand called UVEX.
http://www.ultraviol...extension-cord/

Among other things, this meter measures the UV intensity of the Blak-Ray lamps I am using.
So I flipped a Blak-Ray onto the meter and took a pic, then put my $2 polycarbonate wrap around goggles over the sensor on the meter and was happy to see the level drop to zero--see below.

Blak-Ray B100-AP shining on UV meter at a distance of 9 inches
UVIVFL: Canon SX50 Unmodified, Blak-Ray B-100AP, 10 s @ f/5.6 ISO 80, No Filters.
Attached Image: Blak-Ray UV at 9inches©DNoe_resize.jpg


Blak-Ray B100-AP shining on UV meter at a distance of 9 inches with $2 polycarbonate goggles over sensor
UVIVFL: Canon SX50 Unmodified, Blak-Ray B-100AP, .6 s @ f/8 ISO 80, No Filters.
Attached Image: UV and polycarbonate©DNoe_resize.jpg


Diptych
Attached Image: Blak Ray_UV_Polycarbonate©DNoe_resize.jpg

If I did this experiment wrong, or am interpreting the results incorrectly--please let me know.

-D

#2 baffe

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Posted 30 November 2014 - 08:02

Thank you damon! Good to know...

Didn't know that the blocking is that strong!

So polycarbonate is not the favourite Material for a uv-lens ;-)

#3 colinbm

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Posted 30 November 2014 - 08:47

Congratulations on your UV meter Damon. I have been looking for one too.
The polycarbonate is the material of choice for UV blocking & is used in safety glasses as well as some eye glasses & sunglasses too.
How does the clear surround compare for blocking UV rays, Please ?
Welding was one of my trades many moons ago & getting a welding flash, is a very uncomfortable experience. A welding flash, is not normally caused by inadvertently looking at a welding arc, but is usually caused, unawares to the person, as it is very strong UV rays (which we can't see) entering the eyes at an oblique angle, from the side of the eye & the person is not aware they have had a welding flash until many hours later, in my case always around 12 to 1am in the next morning, waking up with extremely sore eyes & feeling like sharp coarse sand has filled your eye or eyes. Nothing will alleviate the pain except time, In most cases a day or two. I had a welding flash once from sheets of aluminium stacked against the wall of the factory & welding was being done on the other side of the factory. I had no memory of even seeing any welding around me that day that may have affected me, but that night I woke with the most severe case of welding flash in both eyes. I had to have a week off work & stay out of the sunlight, not that I could have anyway. The second week I had to wear the dark green welding goggles to & from work as daylight was still too uncomfortable.
This is why I am asking about the clear surrounds of the polycarbonate goggles Damon, do they attenuate the UV as well as the lenses, this is most important that they do.
Cheers
Col

Edited by colinbm, 30 November 2014 - 08:51.


#4 Damon

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Posted 30 November 2014 - 19:26

The goggles I am using have tiny vent holes in the sides which I am thinking is not only not needed, but might be leaking UV. I will try the sides on the meter and see what it shows. I wonder if scotch tape blocks UV. I will try that as well. Cool having a little meter.
Col-I still weld from time to time in my shop--mainly arc welding. That welding flash sounds downright terrible.

-D

#5 Damon

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Posted 30 November 2014 - 23:58

OK Col you own me $2.

I had to sacrifice one pair off my pile of goggles for this part of the experiment.

Blak-Ray B100-AP shining on UV meter at a distance of ~7 inches with the sides of $2 polycarbonate goggles placed over the sensor
UVIVFL: Canon SX50 Unmodified, Blak-Ray B-100AP, 1/30 s @ f/5 ISO 80, No Filters.
Attached Image: UV meter & sides of polycarbonate goggles©DNoe_resize.jpg


Blak-Ray B100-AP shining on UV meter at a distance of ~7 inches with parts that have vent holes of $2 polycarbonate goggles placed over sensor
UVIVFL: Canon SX50 Unmodified, Blak-Ray B-100AP, 1/40 s @ f/5 ISO 80, No Filters.
Attached Image: UV meter & sides with vent holes of polycarbonate goggles©DNoe_resize.jpg


-D

#6 colinbm

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Posted 01 December 2014 - 01:33

Thanks for doing this Damon, that is reassuring to know that the soft surround of these goggles attenuates UV too.
Do realize that having the perforated mesh on the light sensor, that the scale to use is the inside 'B' scale, which, "are only relative measurements, not in microwatts/cm2".
From the paragraph headed, Measuring High Intensity Lamps........ http://www.uvp.com/m...ls/81003201.pdf
What is your PayPal address & I will gladly refund the cost of the test thanks.
Cheers
Col

#7 Damon

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Posted 01 December 2014 - 02:11

Yeah I read that in the instructions that's why I put it on there. They said I would need to use it to measure these high intensity lamps. However, no UV at all got past the polycarbonate when the sensor was completely covered, which is what I did want to know.
It may be relative, but it still a measurement. It must mean something. Do you understand what it means when in that paragraph about measuring high intensity lamps?
Looks like it can do black lights for sure.

However, it says this too:
The J-221 is calibrated to accurately read the irradiance from longwave phosphor coated
lamps. If used to measure irradiance from a 365nm line source (B-100 type lamp), it will
read approximately 35% higher than the actual irradiance. To obtain the true value, the
reading should be multiplied by 1/1.35 = .74.


So doesn't that mean I can get close to what my lamps are emitting?

I don't really want the 2 bucks! Just kidding there. Really, please don't send me $2--I will send it back!

-D

#8 colinbm

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Posted 01 December 2014 - 02:28

Thanks Damon
I guess they calibrate the meter to the longwave 365nm, woods glass phosphor coated fluro tubes.
You can use the clear cover (UV blocker) on the meter to measure the relative IR the UV lamp is putting out too.

I'll buy you an ice cream then...... but I am now sure it will arrive home :P
Col

#9 Damon

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Posted 01 December 2014 - 02:57

I also measured that--None of the 3 lamps I use give out any relative IR. Gauge never moved.

Pistachio please...

-D

#10 colinbm

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Posted 01 December 2014 - 03:06

I'll give it a go :P
Col



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