Abstract: Sorbed sodium ions in the wood pulp are recovered in the washing operation following cooking with the minimum use of pH control acid, thereby reducing cost and any possible undesirable side effects. A washing press is used in the pulp process. Means are provided for adding an acidifying chemical to the washing press for controlling pH of the pulp suspension. The filtrate from the washing press is divided, with the larger portion of the filtrate being fed to the pulp suspension line to the washing press for pulp suspension pH control. A smaller portion of the filtrate is fed countercurrently through the brown stock washing system. The chemicals are then recovered from the brown stock washing system filtrate.