Survival Blanket or 2mil Hydroponic Mylar?
January 3, 2012 4:40 PM   Subscribe

What is the reflective difference between Survival Blanket Mylar and hydroponic quality 1mil or 2mil Mylar?

I'm preparing to start seeds for the summer and figured I'd reflect and capture some of the sunlight in a window to keep the plants from leaning so much. The price on the survival blankets looks much cheaper then buying a roll of hydroponic Mylar, so is there a particular difference that I'm missing? Obviously the purchase roll might be a bit thicker at 2mil, but I'm curious if they reflect differing amounts of light, or different wavelengths, etc.
posted by wonderfullyrich to Shopping (6 answers total)
They are most likely both aluminized mylar, so I think the reflectivity will be identical as far as your plants can tell. The survival blankets are probably thinner and less durable.
posted by pombe at 4:44 PM on January 3, 2012

I got neurotically scientific about my greenhouse light levels last summer and researched various materials, even going so far as buying a damn light meter. Turned out a coat of white paint was just as good as anything else, and even the most specialised high-end gear would've only netted me an extra 1% luminosity.

The main issue is that smooth, highly reflective sheeting like space blankets can cause hot and cold spots wherever the surface is folded or crinkled, and obviously the flimsier the material, and the bigger your grow area, the trickier it is to ensure an absolutely even light distribution. There's stuff like diamond-textured mylar that gives more diffuse reflection (though slightly weaker per cm3) to smooth out anomalies, but of course that's costlier than the makeshift (i.e. paint/tinfoil/space blanket) approach.

If it's just for a windowsill/shelf sized grow area, I should think space blankets would work fine. AFAIK there's no concerns about limiting the wavelengths of the reflected light; harmful focusing is all you really have to worry about.
posted by Kandarp Von Bontee at 5:16 PM on January 3, 2012

I don't know a thing about plants, but I did spend a summer in a 1-room apartment without a/c, during which I taped up a survival blanket in the window to block sunlight. It did keep the sun off but was a colossal pain in the ass, for 2 reasons:
1) It comes out of the package all folded, and the creases never really go away so it looks, well, like a survival blanket in a window.
2) Noise! I had a constant crinkle crinkle all day and night.

Plants probably don't care about crinkles, tackiness and noise, but if its your living/bed room, you might! Beware.

(If you've got tools, you might be able to staple the blanket to a wood frame [like a canvas stage flat] to cut down on noise and ugliness, or staple to the walls if you're allowed)
posted by Wulfhere at 8:46 PM on January 3, 2012

Response by poster: Who knew survival could be a "colossal pain in the ass" (a great saying btw, it rings of a colostomy in the ass in my head for some reason).

Seriously, good info from you all. Thanks! As it's not in a normally occupied area, I'm not to worried about the crinkling, but I think I will take your advice about framing the mylar. It's also good to know that the reflection is not dramatically different then white paint, although I admit it's surprising. I guess I should probably supplement it with a small grow light.
posted by wonderfullyrich at 6:29 AM on January 4, 2012

Flat white paint on an old sheet would work every bit as well and make no noise at all.
posted by flabdablet at 8:07 AM on January 4, 2012

A possible strategy to mitigate both uneven reflectivity and fold/crinkle issues is to laminate the survival blanket to the back of a piece of frosted/diffuse plastic. Use a repositionable spray adhesive, apply as you would apply self-adhesive vinyl.
posted by a halcyon day at 9:56 AM on January 4, 2012 [1 favorite]

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