We observed that the thickener is essential for emulsion stability. The stability was judged on the basis of changes in appearance, especially macroscopic separation. At low thickener concentrations the emulsions separate within a few hours. Above a critical concentration of thickener the emulsions show a yield stress (Fig. 3) and are stable. Aqueous solutions of the neutralized thickener have a lower yield stress than the corresponding emulsions. This suggests that interactions between emulsion droplets and polymer network increase the yield stress.