An edible, biiayer film consisting of a layer of stearic-palmitic acid and a layer of hydroxypropyl methylcellulose was situated between two food components of markedly different water activities to determine the film's ability to retard equalization of water activity. Tomato paste or salted tomato paste was used as the high-moisture food and ground crackers were used as the low-moisture food. Compared to a filter paper control, the bilayer film substantially slowed transfer of water from the salted tomato paste to the crackers during 14 days at 25°C and 21 days at 5°C. During 70 days at -20°C, the film essentially stopped the transfer of water from tomato paste to the crackers.