Done with mirrors
- Thread starter Rahz
- Start date
Randomblame
Well-Known Member
Possible... or other reflective plastic coating like use in cheap reflectors. I'll order a pack and see myself; they are cheap.
Rahz
Well-Known Member
Some cursory research, UVB isn't going to survive the glass but near-IR is relatively unaffected. My lamps aren't putting off UVB anyway. Soda-lime (common glass) has a transmittance dip at 1000nm, about 90% transmittance compared to visible light.
Regarding diffusion, it's true that looking at a light source in a mirror can be blinding, but this will be true from any angle in which the light source can be seen. Whether this is noteworthy I'm not sure. I'm using 23 cobs in an 18sq/ft area so I question whether more diffusion is desirable. It's not feasible for me (I only have LED) to do the experiment but I could probably show that certain lamp to canopy/lamp to wall ratios will increase the hotspot with single bulb solutions. In a typical cob setup my expectation would be an even increase in light across the whole space... though it's possible there will be somewhat less diffusion. It seems the increase in light over flat-white will negate minor variations in light distribution.
At any rate, I'll take a grid reading before pulling the panda plastic out and after the glass is installed, maybe at a couple different heights.
Regarding diffusion, it's true that looking at a light source in a mirror can be blinding, but this will be true from any angle in which the light source can be seen. Whether this is noteworthy I'm not sure. I'm using 23 cobs in an 18sq/ft area so I question whether more diffusion is desirable. It's not feasible for me (I only have LED) to do the experiment but I could probably show that certain lamp to canopy/lamp to wall ratios will increase the hotspot with single bulb solutions. In a typical cob setup my expectation would be an even increase in light across the whole space... though it's possible there will be somewhat less diffusion. It seems the increase in light over flat-white will negate minor variations in light distribution.
At any rate, I'll take a grid reading before pulling the panda plastic out and after the glass is installed, maybe at a couple different heights.
Rahz
Well-Known Member
Mirrors are breaking. Out of 5 mirrors I've managed to get two out of four of the odd sized pieces I need. Between the glass being thin and the long thin shape of the mirrors, getting them to split correctly is being problematic.
On the plus side, I had decided to leave the plastic backing and it's pretty tough so no shards laying around. This will also be true if the mirrors crack in the grow environment.
The method I've settled on with these mirrors:
Deeply score the plastic backing around the mirror with a razor.
Crack the frame at the corners with metal shears.
Pull the frame pieces off.
Use a razor to shave off the adhesive.
Clean up remaining adhesive with WD40 (or liquid wrench)
I will need to buy more mirrors but assuming I can get another two pieces from the remaining mirrors I will only need to spend about $30 more to finish the space. The back wall and most of two sides are already in place, looks nice. I'm headed to Home Depot to grab more while they're still available.
On the plus side, I had decided to leave the plastic backing and it's pretty tough so no shards laying around. This will also be true if the mirrors crack in the grow environment.
The method I've settled on with these mirrors:
Deeply score the plastic backing around the mirror with a razor.
Crack the frame at the corners with metal shears.
Pull the frame pieces off.
Use a razor to shave off the adhesive.
Clean up remaining adhesive with WD40 (or liquid wrench)
I will need to buy more mirrors but assuming I can get another two pieces from the remaining mirrors I will only need to spend about $30 more to finish the space. The back wall and most of two sides are already in place, looks nice. I'm headed to Home Depot to grab more while they're still available.
SSGrower
Well-Known Member
So whats the problem?I found 51x51mm dielectric mirrors for $165 each. I would need 2220 of them. Cost to cover the walls with them: $366,300
Viceman666
Well-Known Member
And once all your walls are in mirror.. you will just need a pole and some strippers for a lot of fun
Rahz
Well-Known Member
Each measurement in the first row was taken 6" from the back starting 6" from the side progressing in 6" increments (6,12,18, 24 and 30"). The second row shows the measurements taken in the center, 6" from the side and same increments from left to right. Average PPFD is calculated by tabulating values for the whole area extrapolated from the data.
Panda Plastic 29" from sensor
412 490 520 571 606
450 539 577 628 658
Panda Plastic 15" from sensor
412 551 693 745 812
453 665 915 964 1038
Mirror 29" from sensor
590 638 685 770 807
593 645 698 772 811
Mirror 15" from sensor
573 647 800 852 907
453 760 957 1016 1070
Panda Plastic average PPFD at 15" - 676
Mirror average PPFD at 15" - 748
Panda Plastic average PPFD at 29" - 527
Mirror average PPFD at 29" - 695
Mirror PPFD increase of 10% at 15" and 30% at 29".
Mirror PPFD decrease from 15" to 29" is -7%
Panda Plastic PPFD decrease from 15" to 29" is -28%
Looking a little closer at the numbers, no notable hotspots vs white.
PPFD increase should approach zero as the lamp to canopy distance is decreased, but there's still going to be some benefit over flat white to some degree, whether it's mirrors or mylar.
Panda Plastic 29" from sensor
412 490 520 571 606
450 539 577 628 658
Panda Plastic 15" from sensor
412 551 693 745 812
453 665 915 964 1038
Mirror 29" from sensor
590 638 685 770 807
593 645 698 772 811
Mirror 15" from sensor
573 647 800 852 907
453 760 957 1016 1070
Panda Plastic average PPFD at 15" - 676
Mirror average PPFD at 15" - 748
Panda Plastic average PPFD at 29" - 527
Mirror average PPFD at 29" - 695
Mirror PPFD increase of 10% at 15" and 30% at 29".
Mirror PPFD decrease from 15" to 29" is -7%
Panda Plastic PPFD decrease from 15" to 29" is -28%
Looking a little closer at the numbers, no notable hotspots vs white.
PPFD increase should approach zero as the lamp to canopy distance is decreased, but there's still going to be some benefit over flat white to some degree, whether it's mirrors or mylar.
Randomblame
Well-Known Member
Wow,
that's an impressive difference!
I would have expected to see 2 or 3% difference but damn 10%... shit, that's like a new light!
What really baffles me is the low 7% decrease in intensity at 29" from sensor. 21% less light loss compared to Panda film is almost unbelievable!
Seems the claim Panda film has 95% reflectivity is just marketing BS.
Compared to mirrows its max. only 80%!
I will not try it, I will definitely do it no matter if it's UVB reflective or not! White paint is also not UVB reflective..
Your contributions are as valuable as ever, bro, and its still worth following your comments.
What percentage of the wall surface do you have covered with mirrors now? ~50% or more?
Pics would be nice if possible..
SSGrower
Well-Known Member
Wonder if the way the plastic was hung had a effect? The plastic itself might be 95 reflective but if wrinkled may not show in these measurements? Also would mylar perform similarly if mounted/laminated to a flat sheet?
The biggest problem I had with mirrors was the same problem I had with mylar, it offered a place for bugs to hide behind, but proper mounting would fix that.
Rahz
Well-Known Member
The plastic isn't perfectly flat, but I don't think it would sway the results that much. What seems to be happening is the diffusion directing light up and other directions. To some degree the photons are still there, but travelling up rather than down and not touching the sensor. Some of those photons would still hit the plant assuming the 29" mark is well below the canopy level.
I should note for this test that the lamp takes up much of the area and is designed to be hung at around 8 inches. If I had measured from that distance I expect the difference would be 2-3%. A more compact lamp would have somewhat better results on plastic at the same distances. That's why I mentioned variance approaching zero as the canopy distance is lowered. But for those who do like to hang their lamp high the mirror would certainly provide a large benefit over white.
@Randomblame, about 2/3 of the space (all but the doors) are permanently covered in mirrors but I taped a few mirrors in place for the test so results were closer to what 100% coverage would be. Originaly I was going to do the doors as well but it didn't seem like a great idea as they are removable. If they were on hinges I would have mirrored them too. I suspect mylar being fairly directional would perform similarly so I'll switch the white on the doors for mylar when I get a chance.
I should note for this test that the lamp takes up much of the area and is designed to be hung at around 8 inches. If I had measured from that distance I expect the difference would be 2-3%. A more compact lamp would have somewhat better results on plastic at the same distances. That's why I mentioned variance approaching zero as the canopy distance is lowered. But for those who do like to hang their lamp high the mirror would certainly provide a large benefit over white.
@Randomblame, about 2/3 of the space (all but the doors) are permanently covered in mirrors but I taped a few mirrors in place for the test so results were closer to what 100% coverage would be. Originaly I was going to do the doors as well but it didn't seem like a great idea as they are removable. If they were on hinges I would have mirrored them too. I suspect mylar being fairly directional would perform similarly so I'll switch the white on the doors for mylar when I get a chance.
Last edited:
Randomblame
Well-Known Member
I usually need 12-14" height with the reptile bulbs because my stealthbox area is 28" wide. With less distance I would get an UVB/A hotspot in the center and the edges would get even less UVB/A. I would expect to see almost the same 10% improvement you get from 15". I don't know how my titanium white paint compares to Panda film but I would thing problably with slighly lower numbers. So 10% should be possible with authentic glass mirrors.
Found a 40pcs pack self sticking glas mirrows with 205x 205x 3mm for ~50$. Enough to cover 24" from my 66" high walls with mirrors. I will only cover the area used in flower the rest I'll leave white. I do not have to remove so much old paint if I do it that way and in veg the lights are anyway dimmed down. Probably the area between 20 and 44" height, below and above this area I'll leave it like it is.
Randomblame
Well-Known Member
Yeah, found them on e3ay but from a locale supplier. Don't know if it's available on e3ay.com..
Budzbuddha
Well-Known Member
Took my 3x3 and lined original tent surface with vivosun mylar .... much better.
Rahz
Well-Known Member
Image as requested. Doesn't show the full length but you can see how I used pieces of the frame to mount the mirrors to the wall. Same treatment at the top. I used packing tape to secure the tops of the mirrors until the trim was in place, then a razor to trim the excess tape away.
Attachments
Randomblame
Well-Known Member
Thanks, man!
That will definitely look impressive when the chamber is filled with tops.
Like infinite fields of plants..
Much easier to keep it clean too.. I'll definately try something similar. My winter break is a bit longer this time so I'll add this to the to-do list.
SSGrower
Well-Known Member
Do you happen to have enough mirror left over to cover your light? Trying to visaline too, but do you think any of the heights measured had light from any cob bouncing off 2 or more mirrors?
DesertPlants
Well-Known Member
I personally never use mirrors because it not only creates a focused reflection, it creates a focused heat spot. I have found much better results using Orca Grow film. It's a flat white and diffuses the light giving even reflection and doesn't create hot spots. It also helps increase the number of angles light hits different parts of the plant. If you think about it in terms of geometry, instead of reflecting at an equal and opposite angle, it spreads the reflection out and can add light to areas that would otherwise not get it.