White shading for greenhouses etc.

 Not exactly topical for the time of year, but thinking ahead.......

I know next to nothing about this stuff, but am thinking about it for
next year on our conservatory, which is south-west facing and gets
very hot.

Does it go on the inside or the outside of the glass? If it's on the
outside, what stops the rain washing it off? Presumably it has a
binder in it, but is it easy to get off again in the autumn?

How is it applied; I assume with a wide brush, but are paint-roller or
pump-up garden spray other options? Is it messy to apply?

Does it reduce heat as well as light, i.e. does it block IR radiation
as well as visible? By roughly how much does one coat cut the
light/heat (e.g. 10%, 50%, 90%, does it say on the tin?). Are multiple
coats a option?

Do plants grow well under it?

What's the white pigment in it? I assume it's chalk as that's cheap,
but there are other possibilities.

Any other comments?


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

 

[snip]


radiation

Very little IR ever gets in from the outside, since the glass absorbs
essentially all of it.

[snip]

Franz

 On Mon, 22 Nov 2004 21:38:39 +0000 (UTC), "Franz Heymann"


So why does my conservatory get hot then Franz? :-)

IIRC ordinary window glass transmits light well into the near IR (i.e.
up to a wavelength of about 3 microns) which includes much of the IR
emitted by the sun. The contents of the greenhouse, or in my case
conservatory, heat up as a result. But the radiation re-emitted by the
plants etc. is in the far IR, because they don't get as hot as the sun
(although sometimes I wonder...). Window glass is opaque to the far
IR, and the heat remains trapped.

Or were you thinking of UV?


--
Chris

E-mail: christopher[dot]hogg[at]virgin[dot]net

 

because the glass gets hot when it absorbs the IR.


--
Martin

 I was always taught that glass lets in long wave radiation but not short
wave, the long wave radiation hitting the soil, plants changes to short wave
radiation and wont pass back out through the glass.