For this particular activity, you prolly want plastic!
I no longer purchase plastic caps because I have substitutes readily available to me every time I go to the grocery store: a plastic bag.
The handles are in the front. I tie a loose knot with the handles, push all of the air out of the bag, and then tuck the knot in the front above my forehead. I sometimes wrap a towel around it.
So the next time you need to DC, just go dig around in that drawer or cabinet where you keep extra grocery bags and plop it on your head! I know plastic caps are cheap, but in today’s economy every cent counts. Also, it’s better for the environment to find an additional use for all of those plastic bags.
If you’ve got a big surplus, remember that a lot of grocery stores offer recycling for plastic bags right there i the store! Happy deep conditioning ladies!