mirrors instead of mylar?

Thebot

Thebot

Well-Known Member
ive wondered this a couple times and just didnt remembered to post when i was on. ive never seen any grow room where people were using mirrors and it seems like it would be far more efficient than mylar with all that light bouncing back and forward infinitely (if the whole room/cab was lined with mirrors). anyone heard anything on this? positive or negative i thought it was something worth looking into.
 
Thebot

Thebot

Well-Known Member
i believe it, it goes through the glass and gets absorbed in the dark layer behind the glass. i had a strong feeling it would be something of that sort considering i havent heard anyone use it for growing. makes sense though.
 
email468

email468

Well-Known Member
not sure where the myth of mirrors absorbing light got started - maybe the cannabis bible - not sure - but anyway - it is false. While it is true, that mirrors do absorb some light that hits them - EVERYTHING but light absorbs some light. But of the objects in this world, mirrors are one of the most "perfect" reflectors. And that is the problem - mirrors don't diffuse the light (like mylar, white paint, etc..) - mirrors FOCUS the light. it is called specular reflectivity (AKA hot spots) if you want to look it up.

but if you want to do a quick experiment - shine a flashlight into a mirror and aim it so the reflected light hits your eyes - pretty bright and focused - now do the same with mylar or another reflective surface and the difference becomes quickly apparent (the light is spread out and more even - diffused).

I should add that mirrors are bad because of the hot spot thing but mostly cause they don't diffuse the light.
 
Hank

Hank

Well-Known Member
Mirrors just give the illusions of one having more plants:-) That's a good thing though.............lolololo

Anyways your better off going with mylar or flat white paint.

Hank.
 
Ratty696

Ratty696

Well-Known Member
email468 said:
not sure where the myth of mirrors absorbing light got started - maybe the cannabis bible - not sure - but anyway - it is false. While it is true, that mirrors do absorb some light that hits them - EVERYTHING but light absorbs some light. But of the objects in this world, mirrors are one of the most "perfect" reflectors. And that is the problem - mirrors don't diffuse the light (like mylar, white paint, etc..) - mirrors FOCUS the light. it is called specular reflectivity (AKA hot spots) if you want to look it up.

but if you want to do a quick experiment - shine a flashlight into a mirror and aim it so the reflected light hits your eyes - pretty bright and focused - now do the same with mylar or another reflective surface and the difference becomes quickly apparent (the light is spread out and more even - diffused).

I should add that mirrors are bad because of the hot spot thing but mostly cause they don't diffuse the light.
Click to expand...
The fact of the matter is that the standrd mirror that we have in our homes DO ABSORB LIGHT
"

Mirrors come in two basic varieties. The most common are metallic mirrors like those found on the walls of Versailles or on medicine cabinets. Metallic mirrors work pretty well, but they have limitations. The most important is that they waste energy, absorbing a small fraction of the light that falls on them. That is because when light, which, like radio waves, is a form of electromagnetic radiation, strikes a metallic mirror the electrons in the metal move just as they do when a radio signal strikes an antenna. Pushing electrons around takes energy, which dims the reflected image. So metallic mirrors cannot be used in applications like communications and high-powered lasers, where minimizing energy loss is important.
For applications in which energy loss is important scientists depend on a more sophisticated device known as a dielectric mirror. A dielectric is a material like glass or plastic, that does not conduct electricity. Narcissus was actually enamored of his image in a crude sort of dielectric mirror, because water is a dielectric. But dielectrics like water or glass do not reflect light well, so practical dielectric mirrors are made by stacking alternating thin layers of two dielectrics. Every time light passes from one layer to the next a little bit of it is reflected. If the thicknesses of the layers are chosen carefully these reflected light waves combine and reinforce one another, strengthening the intensity of the reflected light. By stacking many layers scientists can make mirrors that are nearly perfect reflectors"

However if you have lots of maney to spend then you would be able to get a mirror that doesnt absorb light.
 
email468

email468

Well-Known Member
Ratty696 said:
The fact of the matter is that the standrd mirror that we have in our homes DO ABSORB LIGHT
"

Mirrors come in two basic varieties. The most common are metallic mirrors like those found on the walls of Versailles or on medicine cabinets. Metallic mirrors work pretty well, but they have limitations. The most important is that they waste energy, absorbing a small fraction of the light that falls on them. That is because when light, which, like radio waves, is a form of electromagnetic radiation, strikes a metallic mirror the electrons in the metal move just as they do when a radio signal strikes an antenna. Pushing electrons around takes energy, which dims the reflected image. So metallic mirrors cannot be used in applications like communications and high-powered lasers, where minimizing energy loss is important.
For applications in which energy loss is important scientists depend on a more sophisticated device known as a dielectric mirror. A dielectric is a material like glass or plastic, that does not conduct electricity. Narcissus was actually enamored of his image in a crude sort of dielectric mirror, because water is a dielectric. But dielectrics like water or glass do not reflect light well, so practical dielectric mirrors are made by stacking alternating thin layers of two dielectrics. Every time light passes from one layer to the next a little bit of it is reflected. If the thicknesses of the layers are chosen carefully these reflected light waves combine and reinforce one another, strengthening the intensity of the reflected light. By stacking many layers scientists can make mirrors that are nearly perfect reflectors"

However if you have lots of maney to spend then you would be able to get a mirror that doesnt absorb light.
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sorry ratty - your information verifies what i just said. EVERYTHING absorbs some light - except, of course, light itself.

You are comparing cheap mirrors to scientifically accurate mirrors but your text says the cheap ones absorb A SMALL FRACTION of light and the better mirrors absorb even less (but still absorb some).

scientific applications notwithstanding, mirrors are the most perfect reflectors available to us. You may want to re-read what you posted and put it in the proper context. they use mirrors in newtonian (and schmidt-cassegrain) telescopes. and what are telescopes but light gathering mechanisms. now why would they use something that absorbs light in an instrument that requires as much reflectivity as possible? because mirrors are the most perfect reflectors we have and they FOCUS (rather than diffuse) light because of it. It is this property that makes mirrors undesirable for growing. Now if you took a mirror and could apply some kind of thin coating like grease or vaseline, you'd probably make a messy but decent surface for diffusing the light properly.

any physics 101 book will verify what i'm saying.
 
Thebot

Thebot

Well-Known Member
hard to follow you guys up but it would be cool to experiment with different diffusion mediums to see what kind of affects/possibilties they may hold. Makes me wonder how sunblock scientifically works, if its bouncing of concentrated wavelengths or what. I don't have any materials to perform any of these experiments, but it would be interesting to see the results.
 
Thebot

Thebot

Well-Known Member
Hank said:
Mirrors just give the illusions of one having more plants:-) That's a good thing though.............lolololo

Anyways your better off going with mylar or flat white paint.

Hank.
Click to expand...
Ive been growing for sometime, I know all that, mirrors just never popped into my head until recently. Don't know why I never gave it any thought until now
 
email468

email468

Well-Known Member
Thebot said:
hard to follow you guys up but it would be cool to experiment with different diffusion mediums to see what kind of affects/possibilties they may hold. Makes me wonder how sunblock scientifically works, if its bouncing of concentrated wavelengths or what. I don't have any materials to perform any of these experiments, but it would be interesting to see the results.
Click to expand...
to clarify - we are discussing "why" mirrors are bad, not "if" they are bad. We agree that mylar or white paint is better - and for growers, that is the important point.
 
Thebot

Thebot

Well-Known Member
I'm not quite sure why that was directed at me. Id already arrived at the conclusion that mirrors don't work for this, you mentioned something about diffusion and I said it would be interesting to experiment with that. plus if they're are reasons why mirrors are bad then the if has already been answered. I really just don't know what you were getting at with that statement
 
email468

email468

Well-Known Member
Thebot said:
I'm not quite sure why that was directed at me. Id already arrived at the conclusion that mirrors don't work for this, you mentioned something about diffusion and I said it would be interesting to experiment with that. plus if they're are reasons why mirrors are bad then the if has already been answered. I really just don't know what you were getting at with that statement
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I said it case someone else was reading the thread and though ratty and i were disagreeing about whether mirrors were bad or not.
just a clarification as my post indicated.
 
rezo

rezo

Well-Known Member
the mirror absorbs lumens not the visual appearance of light. so the light reflected has alot less lumens in it.
 
email468

email468

Well-Known Member
rezo said:
the mirror absorbs lumens not the visual appearance of light. so the light reflected has alot less lumens in it.
Click to expand...
lumens/photons/whatever you want to call them - mirrors absorb less light/lumen/photons/whatever than most other substances. the fact that mirrors are such good reflectors so do not diffuse the light properly is the problem for using them to grow.

again - any physics 101 book has this info in it.
 
oscarmiya

oscarmiya

Drugs Taught Me Metric!
Man, not to keep this 'debate' going but I just did a little research on this and I don't understand why Mirrors would so be bad?
You keep mentioning mirrors don't diffuse the light properly but light emitted from the bulb isn't diffused is it?

Like you have mentioned, Any object your eyes can see absorbs light, just as everything has a thermal expansion rate.

A FLAT mirror reflects light just as it is shown the light (Magnification Rate of 1). Meaning, If you stand infront of a mirror, your reflection will appear the same height and distance. I think you or someone else mentioned Mirrors being used in Telescopes, so that means they are good reflectors. Which from my 'research' would be spot on, to replicate the image your looking at with the most clarity.

That all being said, it seems if you could replicate the light as real as it is Emitted, how could mirrors be deemed shitty material for a grow room? As for 'hots spots', I can't possibly imagen why a perfectly flat mirror would ever cause a hot spot... How? I could see if the mirror was concave.. but not flat.

I always thought the reason Mirrors aren't used in grow rooms was it would be too much of a pain in the ass to cut each one to fit properly, not to mention the outragoues price it would cost.

Just another thought.. If the light was reflected using a Mirror, without any 'Diffusion'... wouldn't that only mean More Penetration (With a flat mirror it could never exceed Max Penetration from the Direct light emitted by bulb)??? Isn't 'Diffusion' in the sense of passing the light through another object (like "clear" grease) just robbing more lumens?
 
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