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Mylar Vs. Foil

  • #41
well you arent going to recover all that is lost, but some is better then none ey ;)
 
  • #42
Hmm it's a thinker...

If I added Mylar to that surface, do you think it'd still make any difference or just end up reflecting that light back into the bulb?

-Nate

Remember incoherent light radiates from the source (unlike coherent light aka LASER) so only a small portion of the light will be reflected back to the bulb.
 
  • #43
To the mylar store! :boogie:

I think I'm going to get a 50' roll. If I have enough left over, I'll be posting some up on the trade board for seeds.

-Nate
 
  • #44
What's the problem with the creases, other that it looking funny, if I may ask? Does it matter if the light is reflected in various directions?

I once read somewhere (maybe at TF?) that having creases can direct focus the light intensity on a small part of you plant damaging that portion; however, I doubt there is much fact in this since most people are using florescent bulbs anyway and the odds of the crease being such a way that it focuses more light than usual on one specific location is probably slim to nil.

Someone else's two cents I thought I'd throw in.

but if I lived near a hydro shop, and I wasnt in the number 3 area for pot production and I wasnt a teacher.. I would go to the hydro shop LOL

The price we pay for following our conflicting dreams/careers!

yeah sure Mr T

I pity the fool!

xvart.
 
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  • #45
Av checks Xvart's ID then passes a cold pint of ale

"Oye, to tall tales of the battles we have fought, the women we have loved, and the CP's we have grown"

Cheers'
Av


xvart, the crease would have to form a parabolic dish wouldnt it hmmmmm :p
 
  • #46
I have always used flat white as a reflector. The diffuse reflector seems to spread the light better. And flat white is nearly 100% reflective.
 
  • #47
Dyflam is exactly right, flat white is also a good reflector...

Which leads to the question, which is better... I dunno, but I have an infrared thermometer and just for fun when things warm up a bit I will coat some pieces of Plexiglas with flat white paint, gloss white paint, Mylar, foil and whatever else I can think of... place them all in the sun at the same time and measure the temp variations

I have always assumed Mylar would be best due to the fact that the high end light fixtures use highly polished metal surfaces instead of flat white, but it would be interesting to see what the temp changes of each surface would be... seems like that would be a good indication of how each surface compares

Be nice to own an infrared thermography camera :)

Where are all our physics majors LOL

Cheers'
Av
 
  • #48
Silver is the best reflector :)
 
  • #49
...I like silver...lol..

I still haven't decided what I wanna do. :p

I'll probably order mylar from either scientificsonline or that other hydroponics site that I found... it was pretty expensive, but it came in a big roll.

Av, make sure you post the results of your experiment!
 
  • #50
dont have to, its already been done ;)


Reflective Chart

Material Reflectivity

Black Less than 10%
Aluminium Foil 55-70%
Semi-gloss White Paint 60-70%
White / Black / White Film 70-85%
Flat White Paint 75-80%
Polystyrene Foam Sheeting 75-85%
Mylar Sheeting 90-92%
 
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  • #51
and I read that if you do use white paint, use a water based, flat white... the other bases may absord some specific wavelengths instead of reflecting them





Reflective Chart

Material Reflectivity

Black Less than 10%
Aluminium Foil 55-70%
Semi-gloss White Paint 60-70%
White / Black / White Film 70-85%
Flat White Paint 75-80%
Polystyrene Foam Sheeting 75-85%
Mylar Sheeting 90-92%
 
  • #52
Ohhhh, cool! That means I need some mylar and double sided tape. :D

Btw, I got the lights and fixtures today, I made sure they were the right ones but DAMN are they big!
 
  • #53
I had always used aluminum foil for my reflector, but because of this thread I decided to give Mylar a try. I ordered some 2 mil Mylar to replace it, and just finished installing it today. I got a 25% increase in light from the Mylar over the aluminum foil.

It was pretty easy to work with – didn’t really wrinkle. I just fed it between the tubes and the metal box of my fixtures, taped it down on the sides of the box with aluminum foil tape, and made a 2” reflective edge around the fixture.

I was somewhat concerned with the prospect of the Mylar being affected from the heat of my fluorescent tubes (melting), so I did some research. I found that the melting point for Mylar is 489° F, it retains good physical properties up to 302° F (maximum service temperature), and can be used up to 392° F. For an experiment, I measured the heat of an incandescent bulb in my house and it was 500° F, so I placed some scrap Mylar on it and in started to melt. I then measured the temperature of my fluorescent bulbs, and they are 130° F. I wedged some scrap Mylar on one of the tubes for a hour and didn’t see any evidence of the Mylar being affected by the heat.

Looks like the Mylar will be a keeper. :banana2:
 
  • #54
I was somewhat concerned with the prospect of the Mylar being affected from the heat of my fluorescent tubes (melting), so I did some research. I found that the melting point for Mylar is 489° F, it retains good physical properties up to 302° F (maximum service temperature), and can be used up to 392° F. For an experiment, I measured the heat of an incandescent bulb in my house and it was 500° F, so I placed some scrap Mylar on it and in started to melt. I then measured the temperature of my fluorescent bulbs, and they are 130° F. I wedged some scrap Mylar on one of the tubes for a hour and didn’t see any evidence of the Mylar being affected by the heat.

Wow. This is great to know. Thanks for conducting this little experiment.

xvart.
 
  • #55
xvart – I never worried about the aluminum foil, and I didn’t think about researching Mylar until I was finished installing it. :blush: Fortunately the heat from my fluorescent bulbs is well within the safe range.
 
  • #56
Nice work Joe,

Always feels good when something works out better then expected (25%), I know I've been well pleased with mine....

Av
 
  • #57
Av8tor1 – yeah, I do like to tinker, and many times it’s hard to immediately know if I’m making a positive difference. Fortunately with this change it was easy – just measure, and more light has to be better!
 
  • #58
wait...i thought mylar was not as good as AF because it was semi transparent!?
Alex
 
  • #59
glider14 - I held a scrap piece of the stuff I got up to a light bulb and it doesn’t appear to be semi-transparent – maybe because it’s reflective on both sides and is 2 mils thick? I did notice that where I scratched the surface a small amount of light does comes through though. I guess that means you should try to handle the Mylar carefully to minimize scratches.

The one thing that was immediately obvious when I removed the AF was that the Mylar looked a lot more shiny/reflective than the shiny side of the AF. Actually the AF looked dull compared to the Mylar. Also, the installed surface of the Mylar is a lot smoother than the AF surface which always has many bumps, creases, etc.
 
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