After cellulose fibers and cellulose ester fibers are co-refined, they are fed to a blend tank continuously feeds a wet laid process. The composition in the blend tank includes co-refined cellulose fibers and cellulose ester fibers and one or more additives, and the cellulose ester fibers have a denier per filament (DPF) of less than 3, a cut length of less than 6 mm, crimped, or non-round with a DPF of less than 3.