These do black out the light nicely, but like another reviewer stated, they are very stiff & look like outdoor curtains. I made the mistake of ironing the lining side of the white curtains, because the front of the curtains remained wrinkled no matter how much I ironed them. That resulted in tiny holes which the light showed through. If you want blackout curtains and don't mind the stiff, look than buy them. I didn't experience as much wrinkling with the 2nd natural pair I purchased, but they do have a stiff texture as well & don't look as bad as the white ones.