Done with mirrors

Rahz

Rahz

Well-Known Member
It's been pointed out that mirrors may only be about 90% reflective while flat white is also about 90% reflective and specialty coatings can be 95-96% reflective. From that angle it doesn't make sense to use mirrors. However there may be some advantages that aren't entirely obvious.

Mirrors won't degrade at the same rate as paint or mylar. A mirror can last a lifetime. It cleans easily. Mirrors don't diffuse light, and this is the main thing I've been thinking about. Even if it's only as reflective as flat white it should still get more light into the canopy. I think even mylar or other reflective coatings will be somewhat diffuse. This could be especially useful for LED when we're placing the emitters near the sides of the canopy space.

I'm currently using panda plastic, just playing around with ideas for my next improvement.

Opinions? Unless someone shoots this idea down hard I might consider doing some testing -vs- flat white and mylar if I can find some.
 
PSUAGRO.

PSUAGRO.

Well-Known Member
Yeah, price&weight have always been the cons for mirrors....ummm GLASS bulbs/houses/hood shields are mainstays in grow spaces for awhile now.


Scarhole used mirrors for year's in his grow room....... no fried buds from supposed "hot spots" ever, ha
 
Last edited:
Humple

Humple

Well-Known Member
I think you should try it out @Rahz - there's been dispute on this topic in the past, so it would be very interesting to see some real-world results. I've seen someone (not sure who - maybe @wietefras?) state that mirrors aren't nearly as reflective as mylar, so it would definitely be cool to see the test data.
 
Rahz

Rahz

Well-Known Member
I'll see what I can do. The experiment doesn't need to be complicated. I can place a single cob at a set distance above the meter and then place a single sheet of material beside the setup... no need to build a fully enclosed area.
 
wietefras

wietefras

Well-Known Member
Humple said:
I think you should try it out @Rahz - there's been dispute on this topic in the past, so it would be very interesting to see some real-world results. I've seen someone (not sure who - maybe @wietefras?) state that mirrors aren't nearly as reflective as mylar, so it would definitely be cool to see the test data.
Click to expand...
Actually I saw a test were mirrors performed at the same level as mylar. Both performed much better than flat white. This 90% reflectiveness of flat whit is indeed including diffuse reflections. Which means part of that 90% is actually reflected back at the fixture or the ceiling. That does not count for our purpose. We need light on the plants and not just scattered randomly around.

Indeed apart from the highly reflective coating, mirrors are easiest to keep clean and keep performing at the optimum level while other forms of reflective material are harder to clean (if at all) and therefore their reflectivity tends to degrade over time.

For instance aluminum foil is also one of the best reflectors, but it's a pain to apply and you can probably only use it for a single grow.

:edit: Oh yeah I said so in that thread Moflow pointed out. But yeah you see the instant knee jerk reactions there. People take the time to do actual tests and the idiots come out and say it doesn't work.

This one sums it up best I guess:
https://www.rollitup.org/t/top-bin-cob-comparison.891010/page-21#post-12216335
 
Last edited:
Rahz

Rahz

Well-Known Member
I found a cheap mirror. It is about a foot wide and 4 feet tall. 5 bucks at goodwill. It doesn't seem to be made from glass so I'm not sure how it compares to a real mirror. It's difficult to say whether it will be more or less reflective than a glass mirror. I suspect the values will be similar, but am willing to consider input on this variable(?).

I will cut a piece of wood with the same dimensions and paint it with flat white. I have a box frame I will use for these experiments. The materials will be mounted to the side of the box to insure they're perpendicular to the ground.

Experiment will be done at night. There will be ambient light but I will take measurements prior to installing each material to show the ambient light and light source are providing a consistent baseline measurement, then I will take a measurement with each reflective material installed. I will repeat several times using different distances.

I'm just about to cut and paint the wood. Probably not going to get to the test tonight but should have some results in the next couple days.
 
Rahz

Rahz

Well-Known Member
wietefras said:
Actually I saw a test were mirrors performed at the same level as mylar. Both performed much better than flat white. This 90% reflectiveness of flat whit is indeed including diffuse reflections. Which means part of that 90% is actually reflected back at the fixture or the ceiling. That does not count for our purpose. We need light on the plants and not just scattered randomly around.

Indeed apart from the highly reflective coating, mirrors are easiest to keep clean and keep performing at the optimum level while other forms of reflective material are harder to clean (if at all) and therefore their reflectivity tends to degrade over time.

For instance aluminum foil is also one of the best reflectors, but it's a pain to apply and you can probably only use it for a single grow.

:edit: Oh yeah I said so in that thread Moflow pointed out. But yeah you see the instant knee jerk reactions there. People take the time to do actual tests and the idiots come out and say it doesn't work.

This one sums it up best I guess:
https://www.rollitup.org/t/top-bin-cob-comparison.891010/page-21#post-12216335
Click to expand...
We pretty much hashed the hot spot out in that thread. What's been tried in the past with other light sources is fairly irrelevant to this test anyway. The hot spot phenomena isn't something I found direct reports of anyway, just foaf type stuff.

As far as the broken glass issue, in a tent situation where someone might bump up against the outside, it could be an issue. Mounting mirrors where the door flaps are could also be a pita. My primary grow area has hard walls now so I don't think about it the same way.
 
Rahz

Rahz

Well-Known Member
I have two sets of results, 6 inches from "wall" and 12" from "wall".

12 inches from wall:
Control - 180 (no wall)
Mirror - 197
Flat White - 186

6 inches from wall:
Control - 180 (no wall)
Mirror - 230
Flat White - 200

Mirror wins. Kinda surprised at the results because they show the mirror being over twice as effective as flat white. Let that sink in. I currently use panda plastic, so I think I should test that material as well before paying for custom mirrors, but I think I can guess what the results will be. I don't have any extra. I will have to cut some out of the grow space to test it.

But I'm probably going to visit the glass man soon to see about some custom mirrors.
 
Rahz

Rahz

Well-Known Member
Here is the 6" from wall results with panda plastic included. I'm kinda surprised at the results but the flat white is brand new and the panda paper is several years old.

6 inches from wall:
Control - 180 (no wall)
Mirror - 230
Flat White - 200
Panda Plastic - 194
 
You must log in or register to reply here.
Top