Inert

Stable, unable to move or act at all, or sluggish in motion. In chemistry, not readily reactive with other elements; thus forming few compounds. Inert substances and materials are not easily decomposed or otherwise modified chemically, which is a particularly desirable characteristic for materials used in art conservation. Acid free papers and cardboards, for example, are more inert than acidic ones, so they degrade much more slowly; they are less likely to become discolored and brittle over time or upon exposure to various conditions during use or storage.Also see hypoactive.