Here is a shot of a 10'x12.5' pandafilm sheet draped over the wooden skeleton of a grow tent in progress. This was 6mm thick, purchased from eBay (HTG) and it is totally opaque.

[img]http://img704.imageshack.us/img704/8241/20100114180216.jpg[/img]

Oh - apparently images are not allowed? Copy and paste into address bar if you want to see the photo.