Standards for library binding:

The weigh of the stripped fabric shall not be less than 7.9 ounces per square yard. The total thread count including wrap and filling, shall not be less than 110 threads per inch. The breathing strength (by strip method) shall not be less than 120 pounds per inch for the filling and not less than 200 pounds per inch for the sum of wrap and filling. - 

Cloth substitutes:  A  material  made up of strong fibre like unlaundered paper is substituted for binder's  cloth. This substitute looks strong enough but is in fact weaker than cloth. 

Paper: Cover boards are  covered with some colourful or cancy thicker paper, thus giving a pleasing look and as well as protecting the cardboard. Many children's books and other popular books are bound in this manner. Wooden boards were used before paper boards were available but now a variety of paper boards is available. They are straw board, mill board, grey board, split boards. 

Straw boards: Straw boards are a  cheaper quality  of board used for smaller and cheaper books. It is made up of straw and is found in abundance in Holland. 

Mill Board: Mill board is manufactured from old hump ropes  and other rags etc. Fine quality mill board are highly calendered. Calendering adds strength to  boards and thus they are made tough and hard wearing. This is a good quality popular board used for standard, books. 

Grey board: This is a medium quality board as it is compact and hardwearing.

Split boards: Split boards are generally used for reinforced library  binding. Thick black mill board is glued to thick straw board to get these split boards.