alginate /al′ji·nāt/ , a salt of alginic acid, extracted from marine kelp. The calcium, sodium, and ammonium alginates have been used in foam, cloth, a thickening agent for foods, pharmaceutical preparations, and gauze for absorbent surgical dressings. Soluble alginates, such as those of sodium, potassium, or magnesium, form a viscous sol that can be changed into a gel by a chemical reaction with compounds such as calcium sulfate; this makes them useful as materials for taking dental impressions.
