Quote Originally Posted by headshake
not to mention that tin foil is more than 30-40% reflective. reflection of the bright side is about 88% while the dull side is around 80%. the problem with using the bright side is that it creates hot spots. do you suppose that it would create hot spots if it wasn't very reflective?

also, flat white paint is not 99% reflective. i think it's around 85% or so. i can't locate the exact number at the moment. why would people buy mylar or panda plastic if they only needed flat white spray paint?
Sorry if my reflectivity numbers didn't jive with Wikipedia...I got my numbers from the Grow Bible (Greg Green). Anyway, my point was that you could improve your grow space by losing the foil and painting the walls white. It's more reflective (whatever the exact numbers) and no risk of heat spots.