A pulp mixture includes a lignocellulosic material, water, lignin, an inorganic salt, and a copolymer including two or more structural units chosen from ethylene oxide units, propylene oxide units, (meth)acrylic acid units, ethyl acrylate units, and combinations thereof. The copolymer is free of silicone-containing structural units and the lignin is present in an amount of greater than about 150 ppm, based on a total weight of the pulp mixture.