(1) Charge aqueous solution containing colloid, buffer, initial persulfate and initial surfactant. Apply heat. (2) Add monomer and persulfate over a five-hour period, maintaining reaction temperature of 167'F (75'C). (3) Intermediate surfactant is added 20 minutes before end of monomer addition period. (4) Following the intermediate surfactant addition, the balance of monomer and initiator are added. (5) Batch is finished conventionally.