Best way to reflect light ?

[freeride high]

is it really an argument?
im a fan of mirrors as an alternative to supplemental lighting, i targeted the popcorn nugs and got some weight on them. you think if i just left the closet white it would be more efficient? i think not.

 

[Rysam]

"generic"mirrors reflect visible light just fine,sort of. the refraction of the glass sends the light waves off in many many directions other than what it started as, but our eyes dont see that. The backing(reflective part) on most "generic" mirrors is just that, generic plastic backing. their ability to reflect the photons, and UV's, and IR that our plants require just isnt there. it doesn't have to be, it may reflect some of them, but not like other surfaces. all they need to do is reflect a single spectrum of light; visible light.
"mirror" is just a word for a reflective surface. Its up to you to choose the appropriate reflective surface for the job and for my $$ there are better alternatives.

 

[GrowerGoneWild]

Because we're talking about the radiation the plant uses to grow with.... not the light that that camera and our eyes see as 'bright'. Even if it's a super-micro thin sheet of glass, it's still diminishing the intensity twice.

Read the threads on putting glass between your lamps and your ladies and you'll understand. No debate, mirrors suck.

I dont believe thats true what you are saying, so you are saying that mirrors cannot reflect PAR light? I dont think thats correct. I can take a mirror and shoot sunlight through a prism and get a full spectrum. And correct me if im wrong but a good portion of PAR , is in the visible range. So if my camera can see it, I think its safe to say that measuring it it a valid way of measuring light intensity or PAR.

Yes I understand that light transmission through glass is a loss, but I do believe that the loss is high. A few percentage each way is still not a huge loss.

I'd argue the glass, and why you need it for a light but its off topic.

Really, the mirror is a two edged sword. If aimed properly, it can direct light back. But if its not aimed correctly, it can reflect light
away from the grow. So I generally stay away from them. There's no denying the reflecting power of an ordinary mirror. I'm sure they could be used in a supplemental way.

I for one do not use mirrors, I prefer mylar or at least white surfaces, but if there just so happen to be a mirror on the wall, I'm not going to take it down.

 

[beejium]

you could slide a piece of white paper in the front frame (if it has one) of the mirror. that way you don't have to take it down or make permanent changes to your mirror. that mirror might cause some heat issues later down the road... just a thought.
anyway to answer the question at hand i have always used flat white, there's nothing to screw up that way. mylar is nice too, but i cannot find it locally, and i really don't want to order it.

 

[GrowerGoneWild]

you could slide a piece of white paper in the front frame (if it has one) of the mirror. that way you don't have to take it down or make permanent changes to your mirror. that mirror might cause some heat issues later down the road... just a thought.
anyway to answer the question at hand i have always used flat white, there's nothing to screw up that way. mylar is nice too, but i cannot find it locally, and i really don't want to order it.

One of my grows happened to have a mirror, and the only time it developed heat stress was when the leaves were touching the light.
So in my experience, that is not the case.

Mirrors can create light "hot spots" but are not literally hot.

Flat white is fine, but its great to diffuse light, but the post title is asking the best way to reflect light. Mylar, works for that.

I do believe the material in emergency blankets is similar to mylar, Or might be mylar. But I'll have to look into that.

 

[beejium]

One of my grows happened to have a mirror, and the only time it developed heat stress was when the leaves were touching the light.
So in my experience, that is not the case.

Mirrors can create light "hot spots" but are not literally hot.

Flat white is fine, but its great to diffuse light, but the post title is asking the best way to reflect light. Mylar, works for that.

I do believe the material in emergency blankets is similar to mylar, Or might be mylar. But I'll have to look into that.

you can see right through the emergency blanket. can you see through the mylar? if you stretch the emergency blanket over your self you can see clear as day. it's like having sunglasses on. about the mirror thing... i never used mirrors, so i didn't know if they got hot, or not.

 

[qwerty]

I'm going to look into this foamcore, I'm interested.

 

[Bluntmaster]

My friend loves his mirrors also. lol
Let's see what he does with the new sog set-up
in his b/r.

 

[FreezerBoy]

Glass absorbs light. Passing through it twice doubles the loss. We suffer glass in air cooled hoods because lamp proximity makes up for the loss. Mirrored light has no such proximity, suffers from the double pass, and is highly directional. A bad choice all around.

Is umber black?

It's a shade of brown, a drop of it, unspread, could easily appear black.

 

[hkush]

I'd have to agree that unlike climate science, reflectivity isn't debatable. Every surface reflects a known and scientifically measured percentage of light. It's not a matter of opinion. I've read the chart (20 years ago), and pure white is the best reflector, slightly edging out mylar. Aluminum foil one of the worst, and I'd venture a guess that mirrors are right down there at the bottom of the list too.

I've looked at Walmart for something good for reflecting and never seen those panels, but I'd hold them up to the light. They might be white, but if they are translucent, whatever light you see bleeding through isn't getting reflected.

Best place IMO is home depot, reflectix, or white painted wall.

 

[Toomp]

I seen Mirrors Set fires on Paper reflected from the sun

 

[canniption]

my reflectors

my reflectors

heres what i came up with a few years ago.foil backed foam insulation bought at lumber store.these measure 8 in. by 3 ft.,the frame is 1 by 3's.i've added foil tape around the edges sinse the pic was taken and it really stiffens them up.they really brighten up the grow area and although i dont have a light meter,i can't look into these.they're a louver type design so you can aim them at different parts of the plant.you could modify these to fit many situations i believe.

 

[beejium]

I'd have to agree that unlike climate science, reflectivity isn't debatable. Every surface reflects a known and scientifically measured percentage of light. It's not a matter of opinion. I've read the chart (20 years ago), and pure white is the best reflector, slightly edging out mylar. Aluminum foil one of the worst, and I'd venture a guess that mirrors are right down there at the bottom of the list too.

I've looked at Walmart for something good for reflecting and never seen those panels, but I'd hold them up to the light. They might be white, but if they are translucent, whatever light you see bleeding through isn't getting reflected.

Best place IMO is home depot, reflectix, or white painted wall.

well that means emergency blankets are worthless for growing.

 

[hkush]

Here we go.

http://books.google.com/books?id=fE...Bg#v=onepage&q=reflective mylar chart&f=false

 

[Chief]

There are two different types of reflection, diffuse and specular. A mirror is an example of specular and flat paint diffuse. Specular will reflect directly in the opposite angle, diffuse will disperse the wave. Most materials exhibit both properties including flat paint.

So to answer you question a mirror will reflect best, in fact a mirror can reflect an almost perfect image. But for our purpose there arfe other things to considerf besides reflection. Mirrors are typically made of glass coated with silver, aluminum, or an alloy. With those materials you have to take into account refraction and the absorption of gthe light spectgrum. Interesting characteristics these metals are that they are amongst the highest optical reflective materials. silver reflects visual light better than aluminum but lacks in UV where aluminum is the best amognst metals.

Refraction is the problem with mirrors and sealed reflectors. Refraction happens when light (other waves also) passes through a material with a different refraction rating causing the wave to slow and change direction (not always direction). Air has a refractive index around 1.003 depending on the glass it can range from 1.4-1.9. Light will slow almostg 2/3 ant an index of 1.5. refraction also has to do with the angle of the source and that goes is explained by snells law (which was mentioned earlier) and critical angles. There is also total internal relfection which occurs when u reach an angle greater than a critical angle.

Oh and mirrors dont intensify heat like a lens but will radiate heat.