If you're an adult coloring book aficionado and you haven't tried Pepin's Artist's Colouring (Coloring) Books and Postcards, you haven't lived. They have super heavy paper for coloring -- 250 gsm (140 lb) -- and will take a mess of scrubbing, watercolor or erasing. Or all three! They also come in large format (B4 size, 9.8" x 13.9" I believe) and postcard sizes. The pages range from sweepingly simple to extremely ornate. Each of the ones I have has a combination of ornate and simple designs. Some of the ornate pages require either a super-tiny tip to color them, or a watercolor wash. However you choose to color them, though, they are delightful. The outlining is done in a pale gray. That makes it so coloring can cover the lines altogether, depending on the media and methods used. However, it can be too light for some people with vision problems. Whatever media you like to work with, I say enjoy these great coloring books to the fullest.