heard that you get 90% light reflexion if you use roofing paint...15 buck, but mylars the way to go:
Mylar reflects about 94% of the light.
One of the best materials on the market for light proofing.

Mylar is a product that serves many purposes. The insulation industry developed this product to withstand severe temperatures. It acts as a moisture barrier as well as a reflector. The United States Navy uses Mylar aboard all of its Freight ships, Cruisers, and Destroyers.

Mylar comes in several different types:
# White

# Black

# Metalized

# Aluminized

# Dimpled Metalized is available also.

# Threaded Aluminized (reinforced)


What we OGer's are interested in is the obvious, we want to wrap our grow space, large or small, with the best reflective material available. Aluminized or Metalized Mylar.
altwnyguy73 Reviewed by altwnyguy73 on . Reflective walls A mate of mine assures me that brilliant white emultion paint is just as effective as foil for reflecting light. I've tryed both in my room. I'm using white at present and this has had no negative effects on yeild or quality. It's much easier and cheaper to paint walls white, rather than pissing about with foil. Rating: 5