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 bobby-j
Stranger
Registered: 04/26/10
Posts: 27
Last seen: 15 years, 5 months
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 plexiglass hood 
#464669 - 08/21/10 07:15 AM (15 years, 8 months ago) |
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anybody ever use plexiglass in a light hood before thinking about making one for cheap i just wanna use it for 150watt hps at most maybe just a 50w,70w or 100w hps from what i read here http://www.rplastics.com/phprofplac.html the stuff can handle 200 degrees farinheit of continuous temp would a 150wat get that hot i'll probbly end up air cooling it too so really shouldnt be a problem in that case, what thickness would be best home depot has .22" .118" and .093" they also have some different names for the stuff optix acrylic sheet lexan polycarbonate sheet is there any difference between these 2 or is it just different brand names http://www.homedepot.com/h_d1/N-5yc1vZ1xh3/Ntk-All/Ntt-plexiglass/h_d2/Navigation?langId=-1&storeId=10051&Ntx=mode+matchpartialmax&style=B&catalogId=10053 i want something with high light transference and heat resistance i guess thinner would transfer more light but thicker would be more heat resistant ive never worked with the stuff before whats the thinest i should go
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kyuzo
Stranger Than Fiction
Registered: 07/05/10
Posts: 981
Last seen: 13 years, 4 months
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Re: plexiglass hood [Re: bobby-j]
#464841 - 08/21/10 02:38 PM (15 years, 8 months ago) |
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Plexi glass tends to be more brittle, and prone to scratching and warping under heat. While Lexan is a softer plastic,and though it's still easy to scratch, is no where near as bad as plexi. I also believe that lexan has a higher heat rating than plexi, and is often used to make insulted panels for green houses.
However, all these benefits come out as close to 4 times the price, and i doubt either would last long in close proximity to hps bulb: (when I built a green tree monitor enclosure from some Lexan-green house panels, the direct heat from a halogen bulb (maybe 1/2-1 inch of space between bulb and plastic) was enough to start browning and bubbling the plastic
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wholesheet
Stranger
Registered: 07/27/10
Posts: 190
Last seen: 12 years, 26 days
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Re: plexiglass hood [Re: kyuzo]
#465304 - 08/22/10 09:20 AM (15 years, 8 months ago) |
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i would just go to a glass shop . tell them u need a piece of heated resistant glass. they can order it for u cut to size..
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bobby-j
Stranger
Registered: 04/26/10
Posts: 27
Last seen: 15 years, 5 months
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Re: plexiglass hood [Re: kyuzo]
#466531 - 08/24/10 12:08 PM (15 years, 8 months ago) |
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kyuzo said:
Plexi glass tends to be more brittle, and prone to scratching and warping under heat. While Lexan is a softer plastic,and though it's still easy to scratch, is no where near as bad as plexi. I also believe that lexan has a higher heat rating than plexi, and is often used to make insulted panels for green houses.
However, all these benefits come out as close to 4 times the price, and i doubt either would last long in close proximity to hps bulb: (when I built a green tree monitor enclosure from some Lexan-green house panels, the direct heat from a halogen bulb (maybe 1/2-1 inch of space between bulb and plastic) was enough to start browning and bubbling the plastic
thanks that helps out a lot how hot do those halogen bulbs get compared to hps do u think 50w hps at maybe 4" with air cooled hood would be ok i really dont want to melt the stuff onto the plants or worse cause a fire
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 Harry_Ba11sach
cannoisseur
Registered: 04/20/08
Posts: 11,753
Loc: Nepal 
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Re: plexiglass hood [Re: bobby-j]
#466533 - 08/24/10 12:11 PM (15 years, 8 months ago) |
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it doesn't really matter how hot halogen bulbs get compared to HPS because they're basically useless for growing plants in the first place 
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kyuzo
Stranger Than Fiction
Registered: 07/05/10
Posts: 981
Last seen: 13 years, 4 months
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Harry_Ba11sach said:
it doesn't really matter how hot halogen bulbs get compared to HPS because they're basically useless for growing plants in the first place
I think he's asking out of the possibility of an HPS running cooler than the Halogen and not effecting the plastic.
But to answer your question, Halogen burn pretty hot: the reason they are used in monitor husbandry is due to the fact that they can create surface temps at 150+ degrees 6-18 inches from the bulb
Personally, I would just go with glass, due to the simple fact that it's not going to get scratched every time you mess with it. Which is going to happen with either lexan or plexi, and drastically decrease your light output
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bobby-j
Stranger
Registered: 04/26/10
Posts: 27
Last seen: 15 years, 5 months
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ya i didnt think halogens where any good for plants good to get some confirmation on that though, and i dont know of any glass shops around here i figured i'd be a lot easier to get some lexan i dont think keep ing it from getting sccratched will be all that hard but i might look into finding a glass place anyways what kind of price difference is there between the lexan and specialy cut glass
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kyuzo
Stranger Than Fiction
Registered: 07/05/10
Posts: 981
Last seen: 13 years, 4 months
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Re: plexiglass hood [Re: bobby-j]
#467412 - 08/25/10 06:41 PM (15 years, 8 months ago) |
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You'll scratch it. Also, you can buy glass at most hardware stores, and they usually cut it. if not, it's really easy to DIY if you're not working with tempered glass.
Not sure how difficult heat resistant glass is to work with, though.
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wholesheet
Stranger
Registered: 07/27/10
Posts: 190
Last seen: 12 years, 26 days
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Re: plexiglass hood [Re: kyuzo]
#468464 - 08/27/10 02:19 PM (15 years, 8 months ago) |
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u will spend about 20 or 25 for a piece of tempered glass that is 20x16" or so.. u have to have tempered glass cut to size i don't think u can cut it
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