Re: Upcycled tshirts into diapers question
You really need 100% cotton for this but 80/20 will work. Don't use anything 50/50 as it's useless. It doesn't know if it is supposed to absorb or repel so it doesn't do anything.
You didn't ask this but if you are making prefolds, be careful how many layers you put in the center strip. If you use the cotton jersey and put too many layers, they will take absolutely forever to dry. I found a few layers of cotton flannel inside the t-shirt prefolds plus a thin doubler worked best.
Can you tell I made a lot of mistakes with t-shirt prefolds? They were our absolute favorites.
Michelle, mom to DD (7/9/99), DD (11/12/01), and DS (4/17/07); wife to DH (8/31/96)