sometimes washed in rebinding. Materials infected with mildew often require fumigation. Rare books and manuscripts are usually stored in a darkened room in which temperature and humidity levels are strictly controlled.

Rare (Nathanson, Conservogram 19/1)
Any such material that has an enhanced value because the demand for the book exceeds the supply, usually because of its importance, scarcity, age, condition, physical and aesthetic properties, association or subject matter.

Slipcase (ODLIS)
A sturdy cardboard box, covered in paper, cloth, or leather, and designed to fit a single book or multi-volume set, with an open front to expose the spines and the volume to remain visible.

Vellum (ODLIS)
A thin, fine parchment made from the polished skin of a newly born lamb, kid, or calf, dressed and polished with alum for use as a writing surface and in bookbinding, before paper came into widespread use in Europe. Also refers to a manuscript written on such a surface, and to a fine-quality off-white paper made to resemble the actual membrane.

Wrappers
A covering which encapsulates the front, back and spine of a book, providing protection from dust, handling and environmental factors. Also called book jacket.