Not sure what percale is but use to be the only thing they used to make sheets and pillowcases from.
I bought a sheet set at Wal Mart and they are so wonderful I went back and bought another set. I have a 4" topper on the bed and the fitted sheet goes over the mattress and top with ease. The fitted sheet never comes off, it has elastic all the way around. I told my Daughter about them, she said they were better than the ones she bought at twice the price. She also bought two sets. They will probably quit selling them because they sell out every time they reorder them. Seems the way they do it at the Wal Mart I go to.