The cleaning of general book collections is typically recommended once a year. Special collections materials may require specialized cleaning procedures because of potential damage that may occur during cleaning. In some cases they will need to be cleaned by a conservator.
It is usually not practical to clean all collections at once in a large library unless an outside cleaning service is brought in. When cleaning is done in-house, the job is often divided into specific projects, where one section of the larger collection is cleaned at a time. This prevents book cleaning from turning into a never-ending (and discouraging!) project.
In most libraries, time and staffing limitations mean that collections are cleaned too infrequently rather than too often. But remember that overdusting and overcleaning of collections increases wear and the risk for damage from handling. Active cleaning of individual special collections items should be performed only when necessary. Storing collections inside boxes or furniture or under muslin dustcovers will reduce the amount of dirt and debris that settles on the collection itself, thereby lessening the need to clean.
Read Cleaning Books and Shelves for a description of the procedures for cleaning general book collections.
In general, cleaning of individual paper objects should not be a high priority for cultural institutions just beginning a preservation program. Because of the potential for damage that may occur during cleaning, the cleaning of paper objects of any kind in a collection should not be undertaken lightly. A conservator should be consulted to assess all the issues relating to the care of the object(s) in question. Objects exhibiting the following conditions should be cleaned only by a conservator:
In addition, if you are unable to positively identify the process by which a photographic object was made, do not attempt to clean it. Even light surface brushing can remove silver image particles from a degraded salted paper print.