Stillman & Birn Archival Quality Sketchbooks - Gamma Series Hardbound - This line of archival quality sketchbooks has a simple premise: When it comes to sketchbooks, paper matters! All of the books in this line are beautifully bound in the United States. The covers are extremely solid and the books literally feel different in your hands than sketchbooks made by other companies- these have a weight and sturdiness that you will notice right away. Made entirely out of archival materials, you will love these books. The Gamma Series hardbound books are made with vellum (cold pressed) surface, 100lb ivory paper. This paper is ideal for use with dry media and will also accept light washes. There are 62 sheets of paper per sketchbook.