Poly-carbonate and light reduction?

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BryanW
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Re: Poly-carbonate and light reduction?

Post by BryanW »

Here's a simple multi use meter, I've used one in the past for placing plants in the best spot for their needs https://www.amazon.co.uk/Firlar-Moistur ... ight+meter
and because they are a 3 in 1 they're still handy, not entirely accurate though.
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Cactus Kid
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Re: Poly-carbonate and light reduction?

Post by Cactus Kid »

Thanks for all of the advice and links, much appreciated (tu)
Joined Havering branch 2006, although have been growing on and off since the age of ten!
Have a large balanced collection of both cacti and succulents but enjoy growing cristate, monstrose and generally anything a bit weird!
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ralphrmartin
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Re: Poly-carbonate and light reduction?

Post by ralphrmartin »

I reckon plants need as much light as they can get - as long as there is ventilation to prevent the plants scorching from build up of heat...

I have found plant can etiolate under a double thickness of safety glass - but that's not polycarbonate...
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DaveW
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Re: Poly-carbonate and light reduction?

Post by DaveW »

Depends what you mean by "safety glass" Ralph, since actual safety glass contains a layer of polycarbonate?

If you mean toughened glass, that is just tempered glass which when it breaks turns to "confetti". If you mean actual safety glass, that is at least two layers of glass with a polycarbonate plastic film sandwiched between, so when it breaks it holds together. Most new car windscreens are now safety glass instead of the old toughened glass. So called Bullet Proof Glass is simply multilayered Safety Glass. The multiple plastic layers between the glasses progressively slowing the bullet and stopping penetration.

https://the-windowco.co.uk/blog/laminat ... ety-glass/

Most "safety glass" used in greenhouses is in fact toughened glass. Laminated safety glass can be cut to size by most glass merchants, but toughened glass has usually to be ordered since it has to be cut before tempering because if you try and cut it afterwards it will just shatter. Whilst toughened glass will stand considerable impacts it is vulnerable to being hit with sharp objects, or having it's edges chipped, which can cause the chip to run and shatter it into "confetti". Which is why the well known TV double glazing advert hits it with a big leather ball and not with a sharp pointed object. :grin:

Tempered glass can sometimes shatter on it's own accord. I replaced a tempered roof glass in a friends greenhouse. He said he heard go off with a bang when he was sitting in his garden in summer and he was picking "glass confetti" out of his plants below for the rest of the year, though none were really damaged. There have been cases of tempered glass tables etc spontaneously shattering, whether due to a manufacturing fault or getting slightly damaged. See:-

https://www.youtube.com/watch?v=7EgAUhsiRQs
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Mike P
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Re: Poly-carbonate and light reduction?

Post by Mike P »

Toughened glass can spontaneously shatter due to nickel sulphide inclusions in the glass as several well known buildings have demonstrated - the original Eurostar terminal at Waterloo being one of them. Heat soaking will find a large percentage of affected panes before they reach the stage of being installed but adds to the cost of the glass so is sometimes not carried out.
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Re: Poly-carbonate and light reduction?

Post by AnTTun »

I grow most of my plants behind polycarb but I had to do that because I was getting more and more burned plants under the plain glass. So far I haven't noticed any change in growth, no etiolation and spines look just fine to me.
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Keith H
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Re: Poly-carbonate and light reduction?

Post by Keith H »

AnTTun wrote:I grow most of my plants behind polycarb but I had to do that because I was getting more and more burned plants under the plain glass. So far I haven't noticed any change in growth, no etiolation and spines look just fine to me.
Do you live at a high altitude?
Here in London the lack of light is more my concern, the neighbouring buildings, trees and overgrown hedges ensure partial shade even in mid summer. I have been replacing the odd broken glass with 4mm solid polycarbonate though this year I may replace all the glass on the most shaded side with twin wall polycarbonate keeping any good pieces to replace the cracked glass on the less shaded sides.
Regards Keith.

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AnTTun
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Re: Poly-carbonate and light reduction?

Post by AnTTun »

No Keith, I live low. But I live in center of town which means houses are close to each other. So my plants get little sun in the morning and afternoon, instead they get the most of the worst (pre and post noon).

I'd say you are on right way, better replace glass gradualy and see what happens in the meantime. Good luck :)
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