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#1
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An explanation of UV light?
I understand there are two kind of UV light, like cholesterol; a good one
and a bad one. Is anybody out there that can explain UV light with regard to transmission through glass and plastic, plant requirements of the stuff and how they use it and if those UV light blocking windows are good or bad. I know in general it affects color quality and perception, pigment fading, greenhouse plastic decay rates... |
#2
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An explanation of UV light?
I'm speaking from no expertise or specific knowledge here (which occasionally does stop me from
responding), but I believe you're referring to UVA and UVB which are merely different wavelengths in the UV spectrum, and are essentially unused by plants. -- Ray Barkalow - First Rays Orchids - www.firstrays.com Plants, Supplies, Books, Artwork, and Lots of Free Info! .. . . . . . . . . . . "Al" wrote in message ... I understand there are two kind of UV light, like cholesterol; a good one and a bad one. Is anybody out there that can explain UV light with regard to transmission through glass and plastic, plant requirements of the stuff and how they use it and if those UV light blocking windows are good or bad. I know in general it affects color quality and perception, pigment fading, greenhouse plastic decay rates... |
#3
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An explanation of UV light?
Al: Wikipedia may be of assistance:
http://en.wikipedia.org/wiki/Ultraviolet Wavelength is inversely related to "strength" of electromagnetic radiation. Shorter wavelengths have more energy than longer ones do; when using handheld UV lights, the shortwave is very dangerous to eyes and skin, for example. The longwave UV light is less harmful. If I remember my physics correctly, UV-A is longwave, and shortwave is UV-B. Most (not al) glass will stop most (99%+) UV-B, but allow much of the UV-A to get through. It is possible to buy specially coated glass that will prevent 99.9...% of the total UV light from getting through. Not sure if this helps or not. Send no e-mail to the address in the header. Spam trap. -AJHicks Chandler, AZ |
#4
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An explanation of UV light?
Is anybody out there that can explain UV light with regard to transmission
through glass and plastic, plant requirements of the stuff and how they use it and if those UV light blocking windows are good or bad. I can shed some light, no pun intended, on the subject of UV light transmission and insulated glass units. Most insulated glass units will block some of the UV radiation in the 300-380 nm range. This includes the red spectrum which some plants need to flower. Standard insulated glass will block 43% of the UV and allow 82% visible light transmittance while insulated units that have a special coating on the inside of the glass, Low E, and are argon gas filled will block up to 87% of the UV while allowing 71 % of the visible light transmittance. Some of these specialty coatings will block almost 100% of the red spectrum and could affect flowering of some plants. The company I work for has been producing garden windows, among other types, for the past ten years that has insulated glass incorporating a special Low E coating and has never had any complaints from consumers related to the growing of flowering plants. There are some greenhouse manufacturers, Four Seasons is one, that uses insulated glass units that have a Low E coating and are argon gas filled. Perhaps someone on this forum has one and could weigh in on the subject. As for plastics most fiberglass greenhouse coverings and lexan insulated sheet material contain coatings to prevent UV degredation and do not affect the flowering of orchid or other plants. If they did not they would turn yellow very quickly and begin to decay. |
#5
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An explanation of UV light?
Actually, the amount and specific wavelengths of light blocked by Low-E coatings depends on the
chemistry of the coating, it's thickness, and to a lesser degree, which surface it coated. I was the technical manager of glass coatings for the company making the vast majority of low-E coating precursors, so get this straight from the guys in the lab who developed the chemistry. Basically, the coating is either an indium-tin oxide coating, or a doped tin oxide coating. The thicker the coating, or the more electrically conductive it is (up to a point), the better the insulation but worse the transmission. The curve on this page (http://www.firstrays.com/plants_and_light.htm) shows that the UV is almost totally blocked at 300nm for a 3000nm Fl-doped tin oxide coating on a single pane of glass, while about 80% of the rest of the plant's usable spectrum gets through. Modern Low-E coatings are much thicker, so just count on moving the curve a bit lower, while more-or-less retaining the shape. -- Ray Barkalow - First Rays Orchids - www.firstrays.com Plants, Supplies, Books, Artwork, and Lots of Free Info! .. . . . . . . . . . . "TRAINMAN9" wrote in message ... Is anybody out there that can explain UV light with regard to transmission through glass and plastic, plant requirements of the stuff and how they use it and if those UV light blocking windows are good or bad. I can shed some light, no pun intended, on the subject of UV light transmission and insulated glass units. Most insulated glass units will block some of the UV radiation in the 300-380 nm range. This includes the red spectrum which some plants need to flower. Standard insulated glass will block 43% of the UV and allow 82% visible light transmittance while insulated units that have a special coating on the inside of the glass, Low E, and are argon gas filled will block up to 87% of the UV while allowing 71 % of the visible light transmittance. Some of these specialty coatings will block almost 100% of the red spectrum and could affect flowering of some plants. The company I work for has been producing garden windows, among other types, for the past ten years that has insulated glass incorporating a special Low E coating and has never had any complaints from consumers related to the growing of flowering plants. There are some greenhouse manufacturers, Four Seasons is one, that uses insulated glass units that have a Low E coating and are argon gas filled. Perhaps someone on this forum has one and could weigh in on the subject. As for plastics most fiberglass greenhouse coverings and lexan insulated sheet material contain coatings to prevent UV degredation and do not affect the flowering of orchid or other plants. If they did not they would turn yellow very quickly and begin to decay. |
#6
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An explanation of UV light?
What a timely subject. I'm having some windows done with a ceramic (and
ceramic/metal) film manufactured by Huper Optik that also significantly reduces infrared. Didn't want to have it applied to windows in plant rooms as the company installing it can't say whether it'd effect the plants or not. Rather not find out the hard way. Here's a link to the products. I'm going with their Ceramic 60 and Sech products. Doug Bolton On Mon, 7 Jun 2004 16:14:20 -0400, "Ray" wrote: Actually, the amount and specific wavelengths of light blocked by Low-E coatings depends on the chemistry of the coating, it's thickness, and to a lesser degree, which surface it coated. I was the technical manager of glass coatings for the company making the vast majority of low-E coating precursors, so get this straight from the guys in the lab who developed the chemistry. Basically, the coating is either an indium-tin oxide coating, or a doped tin oxide coating. The thicker the coating, or the more electrically conductive it is (up to a point), the better the insulation but worse the transmission. The curve on this page (http://www.firstrays.com/plants_and_light.htm) shows that the UV is almost totally blocked at 300nm for a 3000nm Fl-doped tin oxide coating on a single pane of glass, while about 80% of the rest of the plant's usable spectrum gets through. Modern Low-E coatings are much thicker, so just count on moving the curve a bit lower, while more-or-less retaining the shape. |
#7
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An explanation of UV light?
Actually, the amount and specific wavelengths of light blocked by Low-E
coatings depends on the chemistry of the coating, it's thickness, and to a lesser degree, which surface it coated. Most of the modern spudder coat Low E is on the number two surface and is made up of two layers of silver with several layers of oxides to make it possible to see through the glass. Hard coat Low E glass used tin based coatings that were fused when the float glass was made. These coatings are typically on the number three surface. They do not perform as well as the spudder coated products, have an oil slick appearance and in most cases do not meet the new Energy Star requirements for shading co-efficient or solar heat gain. They typically only block about 55% of the UV. |
#8
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An explanation of UV light?
Do any of these coating remove wavelengths that interfere with plant growth
or damage skin or plant tissue cells. I always thought it was impossible to tan underglass, but maybe that is just lore. Infra-red and ultra violet are wavelengths are on opposite ends of the visible spectrum. Do plants utilize these wavelengths? Are they bad for them in any way? red and far red wavelengths are necessary for photosynthesis. When I wrote my question, I was thinking about infra-red but I was reading about ultraviolet in a brochure. I had just bought a new plastic film for my greenhouse called "Kool Lite 380 6mil Greenhouse film" It is a silvery slightly opaque plastic when new. More opaque and silvery than clear plastic, for sure. The advertisement says: reflects green light to reduce heat reduces greenhouse temperatures up to 15 degrees F. the warmer the temps, the greater the reduction 84.5% PAR light transmition with 62% diffusion Blocks UV light up to 380nm for brighter flowers and leaves removes liver spots. well not that last one... Actually I noticed the colors on the flowers where much brighter as soon as I went in after it got covered. So how does blocking UV light of this wavelength produce flowers that appear more colorful? What is PAR and why is it important? I know I am usually the first one to say "look it up" :-) But it might be nice to get some of this in the archive, if it isn't already there. I am lazy too. "TRAINMAN9" wrote in message ... Actually, the amount and specific wavelengths of light blocked by Low-E coatings depends on the chemistry of the coating, it's thickness, and to a lesser degree, which surface it coated. Most of the modern spudder coat Low E is on the number two surface and is made up of two layers of silver with several layers of oxides to make it possible to see through the glass. Hard coat Low E glass used tin based coatings that were fused when the float glass was made. These coatings are typically on the number three surface. They do not perform as well as the spudder coated products, have an oil slick appearance and in most cases do not meet the new Energy Star requirements for shading co-efficient or solar heat gain. They typically only block about 55% of the UV. |
#9
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An explanation of UV light?
Al, I don't think UV plays a direct role in plant metabolism, and IR does only to warm the poor
things up. It seems doubtful that any company would risk selling a "greenhouse film" that detracted from plant growth. Think of the lawsuits... -- Ray Barkalow - First Rays Orchids - www.firstrays.com Plants, Supplies, Books, Artwork, and Lots of Free Info! .. . . . . . . . . . . "Al" wrote in message news Do any of these coating remove wavelengths that interfere with plant growth or damage skin or plant tissue cells. I always thought it was impossible to tan underglass, but maybe that is just lore. Infra-red and ultra violet are wavelengths are on opposite ends of the visible spectrum. Do plants utilize these wavelengths? Are they bad for them in any way? red and far red wavelengths are necessary for photosynthesis. When I wrote my question, I was thinking about infra-red but I was reading about ultraviolet in a brochure. I had just bought a new plastic film for my greenhouse called "Kool Lite 380 6mil Greenhouse film" It is a silvery slightly opaque plastic when new. More opaque and silvery than clear plastic, for sure. The advertisement says: reflects green light to reduce heat reduces greenhouse temperatures up to 15 degrees F. the warmer the temps, the greater the reduction 84.5% PAR light transmition with 62% diffusion Blocks UV light up to 380nm for brighter flowers and leaves removes liver spots. well not that last one... Actually I noticed the colors on the flowers where much brighter as soon as I went in after it got covered. So how does blocking UV light of this wavelength produce flowers that appear more colorful? What is PAR and why is it important? I know I am usually the first one to say "look it up" :-) But it might be nice to get some of this in the archive, if it isn't already there. I am lazy too. "TRAINMAN9" wrote in message ... Actually, the amount and specific wavelengths of light blocked by Low-E coatings depends on the chemistry of the coating, it's thickness, and to a lesser degree, which surface it coated. Most of the modern spudder coat Low E is on the number two surface and is made up of two layers of silver with several layers of oxides to make it possible to see through the glass. Hard coat Low E glass used tin based coatings that were fused when the float glass was made. These coatings are typically on the number three surface. They do not perform as well as the spudder coated products, have an oil slick appearance and in most cases do not meet the new Energy Star requirements for shading co-efficient or solar heat gain. They typically only block about 55% of the UV. |
#10
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An explanation of UV light?
Al asked:
What is PAR and why is it important? I know I am usually the first one to say "look it up" :-) But it might be nice to get some of this in the archive, if it isn't already there. I am lazy too. "Photosynthetically active radiation." PAR is that portion of the electromagnetic spectrum that plants can use to make energy. You can spend a million bucks simulating pure sunlight- the plants won't care, since they don't use it all. See for example: http://ww2.mcgill.ca/biology/undergr...t07/absorb.gif Nice peaks in the red and the blue, and a whole lotta nothin' in the middle. Plants also use "helper" molecules to capture photons outside of these regions; their contribution is relatively small. The e-mail address in the header doesn't work. Spam trap. -AJHicks Chandler, AZ |
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