Hygroscopic substances

The terms 'desiccant' and 'humectant' are opposites of each other. However, both of them have been described as 'hygroscopic' substances. If desiccant and humectant are opposites of each other, how come both of them are hygroscopic?


I think this comes into the ambiguity of "opposites", the actual molecules will function similarly - they create low energy bonds with water, thereby drawing out water from adjacent fluids/surfaces. The difference is where they are used.

A desiccant is placed in the same container as what is supposed to be kept dry. It therefore absorbs water away from the object.

A humectant is placed on the surface of what is supposed to be kept wet. Or in the case of food additives inside the food. This draws water into a desired area.

They are opposites because the usage results in the opposite effect occurring with respect to the desired good, as opposed to the actual substance.