I don't like working with blends. I find 100% cotton the easiest to work with and they behave themselves and I don't have to worry when I take a really hot iron to them for pressing. Also 100% cotton is more forgiving. If a block is slightly small you can block it and spritz it with water and when it dries it will be the full size I need, I don't think a blend will do that but don't know for sure. I learned early on to only use 100% cotton. It is what I like working with so if it ain't broke don't fix it is my motto.