Chemistry
A humectant is a hygroscopic substance. It is often a molecule with several hydrophilic groups, most often hydroxyl groups, but amines and carboxyl groups, sometimes esterified, can be encountered as well; the affinity to form hydrogen bonds with molecules of water is crucial here.
Because of their common use in preservation, it is usually desirable for a desiccant to be substantially chemically stable or chemically inert, and a number of useful desiccants with this property have been identified and are in common use, such as silica gel, chalk and clay-based desiccants.
Read more about this topic: Desiccant
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