Abstract: Processes for washing zeolites, preferably less than about 0.5 micron in size, with a microfiltration system employing a washing liquid, such as an aqueous solution or water (preferably deionized water), to produce zeolite crystals having a zeolite pH in the pH range of 9.4 to 10.0 are provided. The zeolite pH is determined by a special procedure. The preferred washing processes include slurring the zeolite crystals with water (or an appropriate wash solution), initially concentrating the slurry with a microfilter to a preselected initial concentration, washing the crystals by adding make-up water at the same rate as the fluid loss due to permeate flow until the permeate pH is below a preselected value, then stopping the make-up flow and concentrating the slurry to a preselected maximum final concentration. A sample of the zeolite is dried and tested for its pH and if within the desired range, the batch of maximally concentrated slurry is dried.