Twin Rivers Paper Company has acquired a New York-based Potsdam Specialty Paper Inc., the company announced Tuesday. The acquisition adds 26,000 tons to the half-million tons of paper the Madawaska-based company produces annually, according to Twin Rivers. PSPI’s mill in Potsdam, New York, manufactures paper used in tape, wallpaper backing, sandpaper, labels, book covers, and medical applications. Twin Rivers, owned in a controlling share by Atl…