Mylar

I am not trying to be a pain here, just the devil's advocate:

Other than the glass part, which is definitely a big factor in what kills the value of the reflected light of a mirror, how is mylar different than a mirror in texture, if mylar is ideally applied perfectly flat? I mean, I don't know what the actual material is that backs the glass of a mirror vs. mylar, but other than that, but in principal, do you see what I'm getting at? My point is, supposedly mirrors are bad because they reflect perfectly straight... and, if paint is applied with a roller, it's basically flat, but has a slightly dimpled texture. It almost makes sense to me that a surface that reflects in many-faceted directions might caress the subtle irregularities of the leaves of our beloved plants most thoroughly.

If we want to achieve subtle perfection, should we not discuss the possibility of the ideal texture and the ideal material as a combination?

LoveIt said:

Other than the glass part, which is definitely a big factor in what kills the value of the reflected light of a mirror, how is mylar different than a mirror in texture, if mylar is ideally applied perfectly flat?

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The direction the light reflects out of a mirror isn't the only problem with it. The biggest problem is that the light energy has to pass through glass - twice, once on the way in and once on the way out. Glass will reduce the light intensity by the fact the light has to pass through it twice in addition to the smaller issue of the further light has to travel the less intense it becomes. So we can pretty much agree that mirrors are not ideal for reflecting light energy. Other than that, Mylar is effectively a wafer thin mirror.

Mylar is that material you see marathon runners wrapping themselves in after a race, although of a thinner variety. They use it for its heat reflective abilities, so bear that in mind - mylar is just as efficient at reflecting light as it is at reflecting heat. Matt white paint will absorb more heat and consequently reflect less light than mylar will, but it's not a huge difference - but a useful one if you're in a high heat situation.

LoveIt said:

I mean, I don't know what the actual material is that backs the glass of a mirror vs. mylar, but other than that, but in principal, do you see what I'm getting at? My point is, supposedly mirrors are bad because they reflect perfectly straight... and, if paint is applied with a roller, it's basically flat, but has a slightly dimpled texture.

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I don't have an issue with the way mirrors reflect light in comparison to mylar over and above the fact that they reflect less light because that light is having to travel further. The further light travels the less intense it becomes.

As I said earlier used effectively, ie completely flat with no wrinkles, Mylar is more effective at reflecting light energy than matt white paint - dimpled or not. The dimpling affect of matt white emulsion paint put on with a roller that adds a small texture to the paint was the method I chose for my own grow room walls for several reasons: Firstly, because in my opinion, matt white paint applied like that has had it's surface area increased and produces a more even diffused reflection than if the paint wasn't textured. This increases it's reflective abilities when compared to Mylar and reduces the 'reflectivity difference' between the two when Mylar is used correctly. Secondly, because doing it that way cost me nothing and I preferred to use the money I'd saved on that in other areas.

In other words, matt white paint put on with a roller, which costs me nothing because I have those materials, gives me a reflective surface that performs only marginally less effectively than mylar and doesn't cost me 10 bucks a metre or whatever mylar costs these days. Mylar in a large space can be pretty pricey, and that money would be better off spent on better lights giving a higher light intensity.

Where the decision becomes more difficult, is when you look at diamond textured mylar (that's the textured mylar version of the matt white paint dimples!) which is thicker than standard mylar and therefore much less prone to crinkles and creases and is much easier to put up. Add in the textured surface and you get the very best material possible for light reflection - significantly better than matt white paint, but we're still only talking 5-15% more effective, compared to say 5% difference between standard mylar and matt white paint (my own estimates).

The choice then becomes a straight forward one - do you want to spend the 15-20 bucks a metre for diamond patterned mylar for that 5-15% increase in reflectivity, or stick with matt white paint that costs you nothing? Some will prefer to have the best possible reflectivity, some will prefer to save the money and spend it on nutrients, EC meter, PH Truncheon or whatever.

Horses for courses really.

seriously, you should check out the thermal shield product I mentioned. It is a mylar infused product so, it is similar in reflection to that of mylar, without all the heat build up...anyway, I highly recommend it.

uh, can some please elaborate on the hot spots for me? , babygro; you do realize that you said 'matt white paint' over and over?

mylar is 5-7% more reflective so... lets say you had 100,000 lumens, would you rather reflect 90,000 lumens or 96,000? and the mylar that was bought was 25'x4' x2 mil and it only cost 25$ at a hydroponics web site, which was cheeper than me buying a gallon of paint and a roller and a roller tray, and wouldn't have to deal with the fumes for days or take hours to paint the walls (most likely twice). so for me flat white is not my favorite option.

going to use mylar not flat white paint so if we could stay on topic plz?

FaCultGen said:

uh, can some please elaborate on the hot spots for me?

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That's already been answered. Why are you asking the question again?

Hot spots are narrowly focused beams of light as opposed to diffused spread light. There, are you going to ask the question again?

FaCultGen said:

babygro; you do realize that you said 'matt white paint' over and over?

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I'm aware of that - what with it?

FaCultGen said:

mylar is 5-7% more reflective so...

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It's only 3-5% more reflective and that's when it's used correctly, as I said previously, or did you miss that part because you could only read 'matt white paint' over and over?

FaCultGen said:

lets say you had 100,000 lumens, would you rather reflect 90,000 lumens or 96,000?

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Don't insult my intelligence with this eyewash.

Do you actually understand how quickly light intensity diminishes the further away it gets from the light source? Clearly not. A 90,000 lumen light lighting a 4 x 4 foot area being used about 18inches to 2 feet from the top of the plants will probably have to travel something like 6-8 feet when it's reflected off the walls, from light source to plant. 3 foot to the wall and 3 foot to the plant. So that's -

90,000/3x3=10,000 lumens hitting the wall surface. Then travelling another 3 feet to the plants would be 10,000/3x3 = 1111 lumens hitting the plant. Now lets try it at 5% less reflectivity.

90,000/3x3=10,000 lumens hitting the wall surface. 10,000 x 5% = 500 - 10,000 = 9,500 lumens. 9,500/3x3 = 1055. 1111 lumens - 1055 = 56 lumens. Congratulations you just spent 25 bucks to reflect 56 more lumens than flat matt white paint would.

Yeah, this is the mathematical version of what I said earlier, but you clearly only read 'matt white paint'.

FaCultGen said:

and the mylar that was bought was 25'x4' x2 mil and it only cost 25$ at a hydroponics web site, which was cheeper than me buying a gallon of paint and a roller and a roller tray, and wouldn't have to deal with the fumes for days or take hours to paint the walls (most likely twice). so for me flat white is not my favorite option.

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I did say quite clearly that if you already have the paint and roller - it costs you nothing, as in my case, which is why I used it. I can live with the 5% loss of reflectivity and if I was to use mylar - I'd use the diamond patterned mylar - not the standard thin stuff which wrinkles too easily, and diamond patterned mylar is about 10 bucks a metre.

FaCultGen said:

going to use mylar not flat white paint so if we could stay on topic plz?

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I think this is incredibly rude to be honest. Your initial question was answered fairly early on and since then people have asked questions about the differences between mylar and flat white paint which I've tried to answer. These forums and contributions aren't just here for your benefit you know?

Good luck with putting that mylar up flat too.

BABYGIRL you are a dick head...

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

are you talking about this answer to my question? because this is hardly in depth...

anyway according to my books flat white paint reflects 85-90% and mylar reflects 90-95% of light so i was using the middle ground and it could be up to 10% more smart ass.
and who said my wall is 3 feet from my plants? or that my light is 3 feet from the mylar? and if your going to talk about lumens i was using that amount as an example.

and by the way if your concerned about other peoples questions then you should go to there threads. not help them jack mine.

now i see why others around this site don't like you either... please don't post in my threads anymore

FaCultGen said:

BABYGIRL you are a dick head...

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That's the usual response from someone who's just had their ass kicked.

FaCultGen said:

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

are you talking about this answer to my question? because this is hardly in depth...

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Focuses light at a point? Isn't that just what I said, what more elaboration do you want? A beam of light will be far more intense than a diffused one and will damage the plant. Ever put a magnifying glass on a piece of paper in the summer sun and focused it till it burnt the paper? Same principle, or is that too complicated for you to understand?

FaCultGen said:

anyway according to my books flat white paint reflects 85-90% and mylar reflects 90-95% of light so i was using the middle ground and it could be up to 10% more smart ass.

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So where did you get the 7% from? According to my math, 85 of the white - 90 of the mylar = 5%. The 90% of the white paint - the 95% of the mylar also equals 5%. So, only if you have your Mylar put up absolutely flat with no crinkles at all will you get anywhere near the quoted 95% of Mylar. You'd also have to have a pretty dirty white wall or poorly applied paint to get the 85% of white paint too. And as I said, I put mine on with a texture so I'd say my white surface was at the high end of the white paint figures, so Mylar in my instance is at a maximum of 5% better than what I have, and that's Mylar being used at it's most effective - which very few people actually achieve.

FaCultGen said:

and who said my wall is 3 feet from my plants? or that my light is 3 feet from the mylar? and if your going to talk about lumens i was using that amount as an example..

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It was a hypothetical scenario based on the likely square footage of output from a 600w HID. The distances may well be less than I quoted, but as you can see by the math, you're getting 100's of lumens benefit, not 1,000's as you seem to think.

FaCultGen said:

and by the way if your concerned about other peoples questions then you should go to there threads. not help them jack mine.

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I contribute to many threads on here and will continue to do so if I see questions in them that are either going unanswered or getting confused by misinformation, that applies to your threads any anyone elses that I see that happening in.

People deserve to be given CORRECT information, not misinformation and ramblings from people who have no idea what they're talking about.

You obviously favour Mylar, considering you've just gone and spent 25 bucks on it, good for you but that's no reason to put people off from using matt white paint.

wow....this got intense. I don't prefer white paint, although, it does work and it does provide a price/performance purpose. Mylar is one too hard to work with, to hard to clean, and difficult to actually get that pefectly smooth surface to get the best reflection possible...that and mylar also reflects heat back onto the plants. Anyway, you could also look into hanging what is called Panda Film or Black and White Poly. It is just a 6mm thick sheet/roll of plastic that is very durable and easy to use/maintain. Plus, the white side reflects 93% of light. Or you can use like I suggested earlier...a product called thermal shield or poly shield....it is a product that combines mylar and the panda film....very good stuff to use. You really should give any of the suggestions a try, IMHO...or use mylar or white paint...just my 2 cents.

Here is an interesting article showing the performance of a multitude of reflective materials. The dude was trying to make a solar cooker, and using reflective material was his only option to focus the sun's rays.

Read on: http://www.fsec.ucf.edu/en/research/solarthermal/solar_cooker/documents/reflectivematerialsreport.pdf

Dizzy

Im a PandaFilm man myself. Easy as pie to apply. No mess like paint. Wanna move your grow? Take it down and put it back up where needed.

Pretty cheap too. Cheaper than Mylar....less hassle than painting.

This is an old post but many things have changed. Most of this bit was a flame war that went nowhere.

Mylar and white paint are not near specific terms. Mylar can be flat and yield the undesirable specular reflection or textured to yield diffuse reflection. White paint comes in many varieties and flats or matts are not all the same. Paints like Kool Seal are highly reflective but expensive. Regular flat white is probably about 75 to 78 % reflective..and that is probably good enough.

But folks..you can texture Mylar to make the flat stuff behave as a diffuse reflector. It will perform just like Orca..or one of the newer high tech films...but it is much cheaper.

I think the point made above..how much do you want to spend harvesting a lumen ? If costs less to make one then to recycle one..why go there. Use the cheap options and plow the saved bucks back into light production.

And remember..if you call someone a "dick head" it is certain that at least one dick head is in the room.

who the fuck said u gota use whole room? i advise makin or repurposing a wood box that u can deck wit mylar a cheap vent i used a dryer foil tube rigedto a floor vent and lites i recomend strongest mounted mid above plantsand suplemental tubez in corners. also make a mylar or foil covered roof for said box and carpet it wit plastic liner then mylar u achieve what i call a (sun box ) i use cfls and a led battery powered led lite wich the plant seems to like it turned some leafs to it, makes me think i should get a led build, but there so $$$ and not sure what lind. good thing bout battery powered led lites no mark on electric bill , i also take cut doritoes bag shiny side up loosly on top of dirt around plant it made the leaves stand up all healthy archin so im guessin its reflective and hella cheap but its trash... literaly so id onlycover dirt wich is black wich eats litelike nobodys biz # so shinny

RalphCurtis said:

This is an old post but many things have changed. Most of this bit was a flame war that went nowhere.

Mylar and white paint are not near specific terms. Mylar can be flat and yield the undesirable specular reflection or textured to yield diffuse reflection. White paint comes in many varieties and flats or matts are not all the same. Paints like Kool Seal are highly reflective but expensive. Regular flat white is probably about 75 to 78 % reflective..and that is probably good enough.

But folks..you can texture Mylar to make the flat stuff behave as a diffuse reflector. It will perform just like Orca..or one of the newer high tech films...but it is much cheaper.

I think the point made above..how much do you want to spend harvesting a lumen ? If costs less to make one then to recycle one..why go there. Use the cheap options and plow the saved bucks back into light production.

And remember..if you call someone a "dick head" it is certain that at least one dick head is in the room.

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uh wrong cuz ima dick with a dick... thats two but god info i just cant pass a chance to be a smart eleck.

Note that white doesn't reflect UVB light.

its far cheaper to stretch lumens with my sunbox method than it is to pay more electrocity for more litrs and risk gettin busted u use to much power they send drones with heat radar another good reasonto deck ary inch of ur sunbox wit mylar it blocks these unconstitional invasions of privacy damn robots! de_wing the drones!

Only keep mirrors in the grow room if you think angry wizards are going to try and rip you. Some thug wizard busts in throwing fireballs and lightning? Block it with a mirror and it'll bounce back in the direction it came from aka the wizard.