Methods of controlling relative humidity in an enclosure that include preparing an aqueous solution, the aqueous solution including a hydratable salt, the hydratable salt including a divalent cation; preparing a second composition, the second composition including the aqueous solution; and polyacrylamide, a copolymer of polyacrylic acid and polyacrylamide, or both; and placing the second composition in the enclosure, wherein the second composition absorbs water from the atmosphere of the enclosure. Devices and systems including desiccants are also disclosed.