I have been making napkins for years - I use quilters cottons, shirting fabric, rayon, cotton/poly blends. I even have some that are kind of a lightweight duck fabric and some that are a lightweight flannel. I used to serge the edges, and then found that I liked it better when I turned them under 3/8 of an inch, and then another 3/8 of an inch and topstitched them with matching thread. They measure 19" before I hem them. When I compared store bought ones, I found that the wider hems and larger size made them look more upscale.