Beta series – Softcover sketchbooks Stillman & Birn beta series Softcover sketchbooks 270 gsm (extra heavyweight), White paper, cold press surface. Suitable for dry and wet media, Watercolor and ink. . Example of recommended usage: working in heavier washes or overlaying washes (glazing) of Watercolor or gouache. Softcover bindings are flexible and lightweight and open totally flat. Acid-free, chloride-free, lignin-free.