• Temperature and Relative Humidity (rH): A cool (70 degrees Fahrenheit or below) and relatively dry (30-55% relative humidity) environment is safe for most books. Avoiding areas with extreme temperatures such as vents and radiators, particularly extended warm temperature and high humidity, is a critical factor in extending the life of your books. Avoid areas with frequent extreme swings in temperature or humidity, as well. These conditions will slow the aging of paper and book cover materials while protecting against mold growth and physical stress on the binding.

  • Storage Locations: Do not store objects of value in poorly- or non-insulated areas such as basements, attics, or garages. These areas are unsuitable for safely storing collections because of typically unsuitable temperatures and rH and higher risk of leaks and floods.

  • Bookshelves: All shelves should be completely flat and not have any protrusions such as splinters or nails. They should have a solid surface, not latticed or slatted.

  • Light Levels: Books should have minimal exposure to all kinds of light and ideally no exposure to direct or intense light. Window shades, curtains or boxes that protect sensitive books are all options to help prevent damaging levels of light.

  • Cleanliness: Regular dusting and housekeeping is important. Not only can dust contain particles that could discolor books but it also attracts pests and absorbs moisture from the air, which in turn can cause mold to grow. Dust books and shelves with dusters that do not contain any fragrances or other chemicals. Books can be vacuumed with a small, soft, brush hose attachment if the vacuum suction can be reduced.



Storing Books on Shelves

For most books, shelf storage is acceptable, but technique is important. Some factors to consider when shelving books are:

  • Size: Shelve books of similar size together, so that the covers are supported by the neighbors on each side.

  • Orientation: Keep shelved books upright. They should not lean. Support with book-ends if necessary, to keep books from leaning or slumping.

  • Large books: Books too large to stand upright can be stored flat and horizontal, fully supported by the shelf underneath. If the book must be shelved vertically, always place the spine of the book downward on the shelf. Books should never be stored spine up. Over time, gravity will cause the text block to loosen or detach from the cover.

  • Damaged or fragile books: If the book's structure is unstable or to keep items in multiple pieces together, a container or support is often useful.

Types of Housing or Enclosures for Books

Books that are rare or fragile benefit from being stored within enclosures. A storage container gives extra structural support, protection from environmental factors, and can help contain any loose pieces. These are common types of housings that are appropriate for book storage: 

  • Paper folders can be useful for loose items such as clippings and papers. Fragile items should be housed individually. Folders can contain multiple items, but it is important not to over-stuff folders.

  • Clear polyester sleeves can also be used for clippings and papers or can be used to create a book jacket. Note that polyester sleeves are not buffered, can add considerable weight and bulk to storage when used on many items, and they carry a static charge that can damage brittle newspapers.

  • Supportive protective enclosures include four flap enclosures and flat boxes with lids the same depth as the base. Standard- or custom-sized boxes can be obtained from many conservation suppliers.



Materials for Housing

As mentioned before, the description of "archival" for housing materials does not have any meaningful definition. When purchasing housing materials look for the following information:

  • Acid-free & Lignin-free: Boxes and paper-based housing materials should be labeled acid-free and lignin-free. Lignin is a naturally occurring component of most papers and when it starts to break down the acidic components can migrate into books and paper and cause deterioration. Some housing materials are labeled “archival”, this designation is misleading and cannot be used as a standard of measurement.

  • Buffered: For most books, storage housing with an alkaline buffer is preferable. The buffer will help neutralize acids that may form in the storage materials over time.

  • Plastics: Plastic housing materials must be made from chemically stable plastics without any additives. This includes polyester, polyethylene, polypropylene, polycarbonate, and acrylic.