Any container can sweat if moisture gets into it and there are temperature changes. As long as it is sealed and the bags are non-porous, that part should be good. Labs often keep chemicals long term for use. Dry , dark ,and cool is the prefered medium to keep them. Frig or freezing is not necessary and can attract moisture. I have kept chemicals in plastic and sealed with moisture absorbents for several years at a time with no problems. The bottom of a closet in the middle of the house in a small ice chest is my prefered method now.