Mylar

OK,so, this friend of mine want to start his first hydroponic/indoor grow and knows allot about the subject, but no matter how much he searches he cant find the answer to this question;

Can he put mylar under the plants to reflect light back up? or is this a bad idea. in one book he owns he read that that is not a good idea because of the tender underside of the leaves. but that book was written in the 80's so... he has found that alot of the info is outdated and inaccurate to modern day cultivation.

so what do you guys think?

i used cheap-o- walmart mylar on my very first hydro/indoor grow. i couldnt really tell it did any good at all, and its not to cool if you mist your plants leaves. it gets dirty so fast and it was so hard to clean i gave up on it all together.

well he's for sure gonna have it on the walls but he wants to put it under the plants too and just wonders if that ok

im sorry i wasnt very clear,,, i use it on the walls also, but i was talking about putting it under the plants is a pain because when you mist the leaves the mist will get on the mylar and make it dirty very fast. i used mylar under my plants on my first bubbler. i had it on top of the tub and to clean it i had to remove all the plants. it was just way to much work and time for me to see useing it again.
as for if he can use it,,,, i dont see why not if he has it setup so that cleaning isnt a prob. but i didnt see it doing any good when i used it under my plants.

its really not worth it plants dont photosynthesis on the bottom of there leaves anyway so whats the point

cool well thanks for the tips guys i'll tell "him" what you said

I have used it on the floor and the cielings to get reflection on all walls and any light bounced up hits the cieling and back down.Itll add some heat but when plants are young it helps.With me after about 2 weeks the area is so dense no light gets below the canopy so probably not much help after the 2 weeks of veg stage

FilthyFletch said:

I have used it on the floor and the ceilings to get reflection on all walls and any light bounced up hits the ceiling and back down.It'll add some heat but when plants are young it helps.With me after about 2 weeks the area is so dense no light gets below the canopy so probably not much help after the 2 weeks of veg stage

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That makes sense... so here's what might be a stupid question, lol: Can you use mirrors instead of mylar?

LoveIt said:

That makes sense... so here's what might be a stupid question, lol: Can you use mirrors instead of mylar?

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Check this thread out......You have to read around the slight arguments but you will get the idea........

using mirrors?

th3bigbad said:

i used cheap-o- walmart mylar on my very first hydro/indoor grow. i couldnt really tell it did any good at all, and its not to cool if you mist your plants leaves. it gets dirty so fast and it was so hard to clean i gave up on it all together.

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I personally, don't like to use mylar at all. Even though mylar is 99% reflective, it not only reflects light to the plants, but also heat. Another thing about mylar is that any wrikles in the material will drastically reduce light reflection. They just started making a new product called thermal shield, Hydro Wholesale offers Wholesale Hydroponics, HPS and MH Grow Lights, HydroWholesale hydroponic Supp: Thermal Shield, 25 ft.

I think this is what all indoor growers should use and I think I have read somewhere that it is 97% reflective....anyway

Flat White Latex-Based paint.................

Need I say more?

P.S.- Fuck Mylar

but that does nothing for protection against vapor or infrared or thermal scopes....but on a pinch and budget...it does get the job done.

Pool said:

Flat White Latex-Based paint.................

Need I say more?

P.S.- Fuck Mylar

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Please explain why a flat white would be better than say an eggshell or glossy ? You would think the flat white would reflect the least amount of light. I was going to go with flat after seeing a few people post it however my wife threw a fit because it will not clean up well.

SuMsHaDy said:

Please explain why a flat white would be better than say an eggshell or glossy ? You would think the flat white would reflect the least amount of light. I was going to go with flat after seeing a few people post it however my wife threw a fit because it will not clean up well.

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Because it doesn't create hotspots so easily and reflects more light than glossy paint. In my opinion, its best to use a roller to put the paint on, because rollers create a little texture in the paint which helps to reflect a more diffused even light.

If you look at some of the better reflectors on the market, all of them use a 'textured' surface of dimpled aluminum - this is using the same principle of light diffusion as the paint put on with a roller.

Also, by creating a 'textured' surface you're effectively increasing the surface area for reflection - more surface area = better reflection = more light reflected.

Mylar's over rated and very few people actually use it correctly anyway.

Ask your wife is she prefers a nice spliff or clean walls.

SuMsHaDy said:

Please explain why a flat white would be better than say an eggshell or glossy ? You would think the flat white would reflect the least amount of light. I was going to go with flat after seeing a few people post it however my wife threw a fit because it will not clean up well.

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White reflects all light. If you get an eggshell colored white, then it reflects mostly yellow, and absorbs a bit of the other colors. If it were black, it reflects very little light. Optics ftw!

My guess as to why flat white is better than glossy white, is because flat white gives a diffused reflection, in which light is equally dispersed everywhere.

If flat white paint applied with a roller would maximize light reflection without the risk of hot spots, and using mylar or "polysheild" (or something) for heat cloaking from detection devices, why not put a layer of mylar stuff, then cover with thin luon plywood, and then paint it?

LoveIt said:

If flat white paint applied with a roller would maximize light reflection without the risk of hot spots, and using mylar or "polysheild" (or something) for heat cloaking from detection devices, why not put a layer of mylar stuff, then cover with thin luon plywood, and then paint it?

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Mylar's pretty effective if used correctly (better than matt flat white paint) - that means put up flat with no wrinkles! Unfortunately so few people actually manage to use it correctly that the mimimal advantage they may get from the extra 5-10% reflectivity mylar has over white paint gets lost.

Mylar is only effective if it's absolutely flat to the wall with no crinkles or creases in it, any creases or crinkles merely fragment the light sending it in all different directions and create hotspots.

well, i have read in "Indoor marijuana horticulture...revised" that mylar reflects 94% to 96% of light, where as flat white reflects 90%. mirrors don't work well because the light has to pass through glass twice (going in through the glass then back through on its way out), so mirrors are a no no.

can someone pleae elaborate on these "hot spots" i keep hearing about?

Mirrors are actually bad because they reflect light all in the same direction. Thats the reason you can see your image in a mirror perfectly. Flat white surfaces reflect all light, in all directions. That is the ideal reflective surface - one that bounces light evenly everywhere around your plant.

Hot spots occur when the reflective surface is concave and focuses the light at a point.