The DLVO theory of colloid stability is applied to the uncatalyzed and catalyzed agglomeration of small primary particles formed in the earliest stages of emulsion polymerization in the manufacture of a carboxylic styrene/butadiene latex. The inverse 6th-power relationship between the stability ratio and the cation concentration revealed experimentally in an earlier work can be confirmed theoretically using variable Stern potentials. The Stern potential changes as parabolic function of log cation concentration. From the viewpoint of DLVO and Stern theory it is suggested that a spacer effect is crucial for the activity of the catalyst used.