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...

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...

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

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.

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.

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.

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.

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.

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.

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