Perfect binding:

The need to find a less expensive process for binding paperbacks led to the development of the 'perfect binding' - Considered as the most imperfect. This substitutes an adhesive for sewing. Development of new materials has made these adhesive bindings almost as durable as oversewn bindings. However, they are not suitable for large or heavy  volumes or  coated  papers. They are, excellent for cheap and porous papers, for publications with narrow inner margins and where it is desired for a books to open flat without undue strain on the spine. 

Binders are able to make up special variations on any of these bindings suitable to the individual need of their customers. 

Because not all library material needs  quality binding the ALA has also approved minimum specification for little used materials. These are referred to as LUMSPECS. For these, Class A specifications are followed in relation to  materials,  where applicable, but covers consist of hard rolled binder's boards with buckram spines. 

Plastic covering for books: Librarian are always interested in attempts at preserving the freshness of newly purchased books for  as long as possible,  particularly those with artistic and decorative dust jackets. Colourful dust jackets attract the patrons to the books. Various methods have been tried to  prolong the, life of these fragile papers, such as backing them, with differ paper or attaching them to the books cover. However, the most effective method is to attach transparent plastic (PVC foil) covers to the book. These covers are reasonably priced and can be easily fitted. The book is also protected from the elements, thereby  achieving the objectives of covervation. They are sometime available in prepared 'sleeves' and the foil is available in rolls of various gauges of thickness.