12. The cover should not separate easily from the book when pressure is applied.
13. Lettering on the back should be legible and put on straight.
14. On opening the book sections at the back should be perfectly smooth, showing that they have not been crushed in backing.
15. Guards for plates, maps, sections, etc., should be so applied as to leave the paper unwrinkled.
CHAPTER IV
MATERIALS
In a recent pamphlet issued by the Government Printing Office, containing a list of materials and articles used in the printing and binding of public documents, the number of items for binding alone reaches the surprising total of 171. Many of these are materials used in marbling, others indicate slight variations of color and weight in standard leathers and cloths. But exclusive of all these the number of materials called for is over forty.
It is not the writer's purpose to discuss all of these forty or more materials, but it seems necessary to mention that many materials other than those used in covering books (always some kind of cloth or leather) are used in binding. Furthermore, the strength of the book after it is bound will depend almost as much upon the materials used in its inner construction as upon those used in covering it. The inner materials, if not wisely selected as to quality or in reference to the kind of service which the book is to receive, may cause an otherwise excellently bound book to give poor service.