Carboxymethyl cellulose (CMC) or cellulose gum  is a cellulose derivative with carboxymethyl groups bound to some of the hydroxyl groups of the glucopyranose monomers that make up the cellulose backbone. It is often used as its sodium salt, sodium carboxymethyl cellulose.The pure CMC used for food, pharmaceutical, and dentifrice (toothpaste) applications. An intermediate "semipurified" grade is also produced, typically used in paper applications such as restoration of archival documents