Mirrors.. no good.... Seriously ...???
- Thread starter SimplySmokin
- Start date
Brick Top
New Member
Evidently you did not read the information about the difference between specular reflection and diffuse reflection. If you had you would not be leaning towards using mirrors.
People need to learn that percentage of reflectivity is not the most important thing in regards to a reflective material for growing. Someone would be better off with a material that is only 80% reflective but it reflectivity is very highly diffuse than using something that is 100% reflective but it's reflectivity is specular.
Brick Top
New Member
I have no idea if that would work. But if the reflective material behind the glass of a mirror would be pebbled or textured as high quality reflective hoods are then it would be a good reflective material to use. It would make for a terrible mirror, but it would then provide a high percentage of reflectivity and also the light diffusion that is needed rather than the normal specular reflection that standard mirrors of all sorts can only provide.This is interesting Brick.., so in line of thinking its the ultra smooth surface that is the problem.. sooo.., Following that line of thinking I could create diffused reflection simply by draping celophane over the mirror taught but not tight leaving a bit of slack for the fans to wave ???
TaoWolf
Active Member
There's really no way to break it down from best to worse like that in absolute percentages or even general ballpark percentages:
Mylar is not largely reflective unless a metallic coating is applied to a surface of it. If talking about aluminum covered Mylar, the percentage of reflectivity would based upon the reflective properties of the aluminum used on the surface. Outside of these forums and sales ads for grow-room Mylar products (which is where most of those often repeated reflectivity values come from), aluminum foil is usually rated at about a 95-97% reflectivity (including by home-safety standards and ratings). Mirrors usually use aluminum sheeting behind panes of glass... aluminum that also has about a 96-98% reflectivity... because it's all aluminum being used, they all have around the same reflectivity and will all vary only a small amount from brand to brand or use to use. Some aluminum foil will exceed reflectivity against that which is used on Mylar and some of the aluminum sheets used in mirrors will exceed reflectivity or both and all that vice versa - but generally will be about the same because aluminum is aluminum and all comes from the same source and the same place (like Alcoa).
Any aluminum can have a specular or diffuse surface texture. Even though the aluminum used in most mirrors is almost always polished to a specular surface, the aluminum used on Mylar and the aluminum pressed into foil sheets can be found with either specular or diffuse surfaces. Specular vs. Diffuse is not a decisive factor in providing any hard figures regarding reflectivity rating because of this. Specular or diffuse actually doesn't have that much of an impact on total reflectivity, it impacts just the directional pattern the photons are in (diffused pattern or not). Photons are not in and of themselves changed by specular or diffuse surfaces and likewise these things don't impact PAR and by extension how a plant will grow. As long as the light is reflecting where you want it, there is no reason to trade in your specular aluminum light reflector for a diffuse one.
The real drawback to house-hold mirrors is the fact that they have glass over the aluminum to protect the polished surface from day to day life in a bathroom. And glass does block/absorb almost all UV radiation, including a small percentage of PAR. Just like when glass is used in hooded reflectors, some amount of PAR is lost to the glass - the loss is compounded when every photon has to travel through a solid layer of glass, twice, in order to be reflected once (double the amount is lost to the glass)... and is there really any need for the glass when growing plants? For hood fixtures yes, for reflective walls... not usually.
The thickness of the glass is also highly variable among mirrors... another reason why it is almost impossible to just state 'a mirror is __% reflective'. It varies a lot because glass thickness varies in addition to the type of reflective surface used.
The only place I've seen aluminuminzed Mylar listed at a firm 97% while simultaneously listing foil at firm 80% has been in a commercial sales ad selling Mylar... Anywhere else you look, all mostly pure aluminum is usually all rated around 97% regardless of how or where it's found (including when pressed into foil sheeting).
Sorry to rant a bit, just tired of seeing that same reflectivity information from the same sales ad being repeated all over growing forums as if it were factual in any way... just a pet peeve.
Brick Top
New Member
There is a lot of confusion about aluminum foil and that in part is because people believe that it is all the same. There are different grades of aluminum and they are not all equally reflective. Some aluminum foil is made from higher grade aluminum but the lesser expensive brands are alloys and are not nearly as reflective as the highest grades.
If someone were to believe the advertising copy on the Reynolds Aluminum website they would claim that aluminum foil reflects approximately 98% of radiant heat and light. That would mean that aluminum foil is more reflective than the very highest grade pure aluminum textured reflective hoods and also more reflective than Foylon, Mylar and C-3 film. But it is not, and especially not the lesser brand names and even more so not the totally generic most inexpensive store brands.
Something else the makers of aluminum foil do not mention when they write about reflectivity is what different areas of the light spectrum it most reflects. When it comes to white light the highest grade aluminum foil, Reynolds, is roughly 85% to 88% reflective. But the silicates used in the aluminum foil reduce it's reflectivity of other color light by roughly 30%. That is why the most commonly used figure for reflectivity of aluminum foil when used as a reflective material for plant growing is is 55%.
Incomplete information and manufacturers advertising copy cause much confusion among growers in regards to how useful aluminum foil actually is.
Rascality Afoot
Well-Known Member
Mirrors do create hot spots. There is also a layer of glass that the light bounces through twice, decreasing intensity substantially. Mylar is cheap enough, or just flat white.
SimplySmokin
Well-Known Member
lol screw it.. Mylar it is.. i guess i do still get a benefit of hanging the mirror.. even covered with mylar it wont get broken lol cause its a huge sunnzabtch.. thx all despite the personal bs I enjoyed and yes learned..
Stinkmeaner
Well-Known Member
sounds like the right answer to me. it really does
TaoWolf
Active Member
Just more confusion without any backing with a lot of percentages being bantered around authoritatively without any backing.
I worked at Alcoa (grew up outside of Knoxville) while going to UT and I know from first-hand experience that the aluminum that is cut into foil comes from the exact same place that all refined aluminum comes from... and that there's really only 2 ways to commercially refine aluminum... and both processes produce over 99% pure aluminum... What you stated is simply not true brother.
But in the wise words of somebody: "Whatever."
withoutAchance
Active Member
im the same as most i am no reshearcher or sicietist just know what i read or am told or figure out at some point in life and cant repete or demistrate or comcunicate nothing more and if my info upset some fuck off and disregard it no need to get all im the shit and i know eveyry thing and u know nothing.
Japanfreak
New Member
I'm still looking at the title of the thread, mirrors no good? Yeah, they are pretty good.
SCARHOLE
Well-Known Member
Me an brick top had this debate already, he gets mad im spreading false info.
I used mirrors cause they are free to me an super reflective.
I wouldnt recomend em cause they are sharp, hard to cut, heavy, an can build mold behind em.
But I believe they dont hurt anything, an definatly reflect an intensily foccused light.
He wants diffused light, i want max reflection.
I think a blend would be the best also. If they had dimpled mirrors free at work I would have lined my box with them.
Mylar would be ok, but i have little faith in white paints ability to reflect without weakening(diffusing) the light too much.
Sure mirrors create hotspots, so do my HIDs, this heat is called light.
Mirrors in sunlight might be too hot, but with lil Hids i can feel NO heat off em.
You wont change Bricks mind JAPANFREAK, he wont change mine, so lets just agree that we dissagree an be civil.
lol
I used mirrors cause they are free to me an super reflective.
I wouldnt recomend em cause they are sharp, hard to cut, heavy, an can build mold behind em.
But I believe they dont hurt anything, an definatly reflect an intensily foccused light.
He wants diffused light, i want max reflection.
I think a blend would be the best also. If they had dimpled mirrors free at work I would have lined my box with them.
Mylar would be ok, but i have little faith in white paints ability to reflect without weakening(diffusing) the light too much.
Sure mirrors create hotspots, so do my HIDs, this heat is called light.
Mirrors in sunlight might be too hot, but with lil Hids i can feel NO heat off em.
You wont change Bricks mind JAPANFREAK, he wont change mine, so lets just agree that we dissagree an be civil.
lol
NONHater
Well-Known Member
Stop hating hater.
Brick Top
New Member
I really love it when people attempt to redefine what I have said or explain it in ways other than how I said it. It is not at all a matter of what I want. It is all about what plants require and what will make them grow the best and when it comes to reflective material, diffuse reflected light is exactly what plants need to grow their best.
You said you want maximum reflection ... and if I remember right, in the past you said you work with mirrors, maybe install them, I do not remember everything you said, and you get them for free and that free is hard to pass up. So you attempt to justify your use of mirrors and validate their worth by relying only on their percentage of reflectivity and totally ignore their specular reflection and refuse to accept that diffuse reflection is vastly better. It covers for you being to cheap or to uneducated in lighting to use a better reflective material.
Your plants would be vastly better off, and grow better, if you used a reflective material that was only 80% reflective but was highly diffuse in it's reflection than you would be if you could use something that is 100% reflective but only gave a specular reflection.
Percentage of reflectivity is not all important. Higher is better but only if a diffuse reflection comes with it. If not, something lower in reflectivity but highly diffuse in reflection would be vastly better.
If you prefer to accept the facts that's cool and the gang with me but remember that this site is supposed to be for learning and a source of information, factual information, so it would be nice if you did not make attempts to redefine what I have said or attempt to put words in my mouth or spread falsehoods about mirrors and their value as a reflective material just because you use them. Anyone who believes what you said will be mislead, learn things that are incorrect and their growing success will be diminished because of it.
Hot spots or flash points occur when bundles of concentrated light rays which are traveling parallel to each other converge. In grow rooms, the hot spot phenomenon is dramatically increased when using a material with a specular reflection as a supplementary lighting source to the grow lamps.
A light beam can be thought of as a bundle of individual light rays which are traveling parallel to each other. Each individual light ray of the bundle follows the law of reflection. If the bundle of light rays are incident upon a smooth surface, then the light rays reflect and remain concentrated in a bundle upon leaving the surface. Regardless of the grow room layout, the use of a specular reflective material on the walls, ceiling, and floors as a supplement lighting device to your grow lamps will be the biggest contributor to hot spots.
On the other hand, if the surface is textured, the light rays will reflect and diffuse in many different directions. The texture of the reflective surface assures that when each individual ray meets a surface it has a different orientation.
The normal line at the point of incidence is different for different rays. Subsequently, when the individual rays reflect off the rough surface according to the law of reflection, they scatter in different directions. The result is that the rays of light are incident upon the surface in a concentrated bundle and are diffused upon reflection.
That is what plants need and if plants actually 'wanted,' that is what they would want. Diffuse reflection is also what plants receive in nature. Light rays strike all sorts of different materials and the reflected rays are scattered in all directions, they are diffused, and that is the type of reflectivity nature provides. Plants evolved over thousands and thousands and thousands of years, or more, to grow best, to make the very most of what nature provided them.
Do you believe that you can reverse or overcome untold numbers of years of evolution just because you get your mirrors free or very inexpensively?
If you knew how plants worked, if you knew what they required, if you had any horticultural knowledge at all the second you finished reading this message you would instantly go to your grow room and rip out all your mirrors and replace them with a high quality reflective material that provides a highly diffuse form of reflection.
But you won't because you will not allow any of this to sink in and you will instead go with what you want and need to believe, in part because of your access to mirrors, and totally ignore every single fact about plants and reflected light.
Burger Boss
Well-Known Member
OK....time out....The OP is satisfied!
Now let's just pack up our charts, graphs, authoritarian mindsets, bruised ego's and all the rest of the silly baggage this thread accumulated, and head out to save the cannabis world somewhere else.....there's more great threads coming.........
Brick Top
New Member
I agree .. but just out of curiosity ... what do you call the 'look,' or the 'style' or whatever of the scary Uncle Fester's brother with hair looking guy in the avatar?
racerboy71
bud bootlegger
dad???..........
Brick Top
New Member
Son? Is that you? If so .. when will you be paying me back the money I lent you for the down payment on your house, you deadbeat?
Burger Boss
Well-Known Member
Hey Guys, LOL, as far as I understand it, it's called "Goth". I found that picture on a website called "Awkward family photos", it's titled "Uncle Jack", I'm sure there's a great story there. Here's the site:> http://awkwardfamilyphotos.com/about-afp/the-official-awkward-family-photos-book/
Enjoy, and Happy New Year....Good luck & good grow.......BB
Brick Top
New Member
Ahhhhhhh .. goth. It's been so many years since I last saw it that I had forgotten about it.
I was never into it myself .. but still I sort of liked the idea behind it ... not the look .... but the idea. It gave the ugly kids a chance to be popular for a change.