My mom uses them over my Dad's sheets or between the sheets and mattress protector. My dad has Parkinsons. She has a pad she loves that is roughly 36" by 36". 80% polyester and 20% cotton, and has a tag marked 'TRS' on it. She said that the instructions said it would last through 250 washes. I cannot find any liners with this type of blend.
I appreciate any help!