Bookbinding and the Conservation of Books
A Dictionary of Descriptive Terminology

 Previous item  Up One Level Next item


A claylike mineral consisting largely of montmorillonite, and characterized by its high absorptive power and active colloidal properties. It is usually dark, dull, and powdery, but waxy on freshly cut surfaces. Its color varies from yellowish-green to nearly black. Bentonites are products of the change of volcanic ash, and are characterized by an alkaline oxide and alkaline earth content of 5 to 11. They are used as a filler in paper, for deinking paper pulp, for decreasing pitch problems in papermaking, and the like. The name derives from its discovery in Benton, Wyoming. (17 )

[Search all CoOL documents]