Testing windows for UV protection
#1
01-05-13, 02:51 PM
Testing windows for UV protection
Is there a way I can test whether my windows block UV light? Should I buy a UV meter? I am interested in preventing my carpets and pictures from fading.
Thanks
Thanks
#2
01-05-13, 03:38 PM
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Probably the cheapest method I can think of is to use inexpensive dark colored copy or construction paper. Take a sheet and cut it into three strips. Put one strip on the sill of the window you want to test, one strip to put in a dark closet and one to put in a plain glass window that you know has no UV protection (storm door or old shed window) and receives about the same amount of sun as your test window . It is important that all be exposed In a month compare all three pieces of paper next to each other. The piece of paper kept in a dark place is your reference for color. The one put behind a storm window is to show that the paper does fade in the sun and then your real test piece to see if the window blocks fading wavelengths.
Or go buy a UV meter.
Or go buy a UV meter.
#3
01-05-13, 07:00 PM
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old school cheap is a cigarette lighter. a flame just in front of the window pane will give you 2 reflections on the inside and 3 on the outside or vise versa = low-e or some type of covering.
#4
01-05-13, 07:28 PM
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I'm not sure that's completely accurate, Darren.
According to PPG's website, there should be 4 reflections on a double paned unit, and it's the color of the reflection that determines where the low-e coating is. I'm color blind, so I can't vouch for that.
But the 4 reflections part is true. Just tested it on a few of my windows. LOL
At any rate, simply having low-e glass does not necessarily mean it blocks UV. It blocks "some" UV, because it reflects a percentage of wavelengths, but to get the best UV protection you need a film that specifically blocks the majority of UV wavelengths. Blocking some of the UV really just slows fading, it doesn't stop it.
According to PPG's website, there should be 4 reflections on a double paned unit, and it's the color of the reflection that determines where the low-e coating is. I'm color blind, so I can't vouch for that.
But the 4 reflections part is true. Just tested it on a few of my windows. LOLAt any rate, simply having low-e glass does not necessarily mean it blocks UV. It blocks "some" UV, because it reflects a percentage of wavelengths, but to get the best UV protection you need a film that specifically blocks the majority of UV wavelengths. Blocking some of the UV really just slows fading, it doesn't stop it.
#6
01-06-13, 05:27 PM
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"According to PPG's website, there should be 4 reflections on a double paned unit, and it's the color of the reflection that determines where the low-e coating is."
thanks for the correction.
at any rate, looking for a different color reflection is the cheapest way to see if any additional UV's are being blocked, after that $30 will buy a cheap tester. the UV light debate is a healthy one. standard clear glass will block UV light. might be a small amount but it will block it.
i hope this helps.
thanks for the correction.
at any rate, looking for a different color reflection is the cheapest way to see if any additional UV's are being blocked, after that $30 will buy a cheap tester. the UV light debate is a healthy one. standard clear glass will block UV light. might be a small amount but it will block it.
i hope this helps.
#7
01-06-13, 08:19 PM
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No problem, thanks for not taking offense- just trying to help.
Yeah its a debate alright, also a marketing technique, since clear glass blocks say 10% of visible light, it "could be" said that it helps block UV light too, since that's also part of the spectrum. Saying that Low-E glass automatically includes UV blockage "may be" misleading, especially if it gives the impression that it blocks a large percentage of UV. Some Low-E may, some may not. Anyone that's really serious about blocking UV light needs to add an applied window tint and get it from a reputable company that guarantees the level of UV protection, and ALSO warranties against damage to the existing IGU (insulating glass unit) due to heat or other unforeseen complications due to adding something new to the glass that might affect the original glass/window company warranty.
Yeah its a debate alright, also a marketing technique, since clear glass blocks say 10% of visible light, it "could be" said that it helps block UV light too, since that's also part of the spectrum. Saying that Low-E glass automatically includes UV blockage "may be" misleading, especially if it gives the impression that it blocks a large percentage of UV. Some Low-E may, some may not. Anyone that's really serious about blocking UV light needs to add an applied window tint and get it from a reputable company that guarantees the level of UV protection, and ALSO warranties against damage to the existing IGU (insulating glass unit) due to heat or other unforeseen complications due to adding something new to the glass that might affect the original glass/window company warranty.
#8
01-21-13, 12:07 PM
A single lite of clear glass will allow about 73% of UV in the 300-380nm spectrum pass thru (UVB is 280-315nm and UVA is 315-380nm). Dual pane, or two lites of clear glass, will pass about 58% of UV.
Dual pane with pyrolytic (hard coat) LowE coating blocks about 54% of UV, while sputter coats range from approximately 76% for single silver, to 85% (or so) for dual silver, to about 95% UV blockage for triple silver coatings.
If you have laminated glass, your windows will be blocking better than 97% (up to virtually 100%) of UV from passing thru the glass.
However, when dealing with fading, you also have to consider visible light as well as UV light. You can still have fading when blocking 100% UV but passing visible (380-780nm).
The best possible combination for fading protection is a triple-silver LowE coating used in conjunction with laminated glass.
Is there something specific that you are trying to protect? Or just a general question?
Regards
Oberon
Dual pane with pyrolytic (hard coat) LowE coating blocks about 54% of UV, while sputter coats range from approximately 76% for single silver, to 85% (or so) for dual silver, to about 95% UV blockage for triple silver coatings.
If you have laminated glass, your windows will be blocking better than 97% (up to virtually 100%) of UV from passing thru the glass.
However, when dealing with fading, you also have to consider visible light as well as UV light. You can still have fading when blocking 100% UV but passing visible (380-780nm).
The best possible combination for fading protection is a triple-silver LowE coating used in conjunction with laminated glass.
Is there something specific that you are trying to protect? Or just a general question?
Regards
Oberon
#9
01-22-13, 03:04 PM
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Hi, Here is an idea that might work.I wear glasses the change tint in sunlight. They don't work in the car. I asked the folks that made the glasses and the said car windows block UV rays and the type of glasses I have use UV rays to change tint. I would think that being the case, if a person with self tinting glasses stood in side your home in front of a window on a sunny day and thier glasses didn't change the window blocks UV rays and if they did change the glass does not block UV Rays.
Good Luck Woodbutcher
Good Luck Woodbutcher
