Glycerin is a humectant, meaning it attracts moisture to a person's skin, says wiseGEEK. Glycerin is both a byproduct of the process of soapmaking, and an ingredient in high-end bathroom products such as lotions, creams and some handcrafted soaps.
Glycerin is a neutral, sweet-tasting, colorless, thick liquid that freezes into a gum paste, according to wiseGEEK. Glycerin works well as a solvent because many things can be dissolved into glycerin much easier than they can be dissolved into alcohol or water solutions. Glycerin absorbs water from the air, and left on its own, it chemically becomes 20 percent water. If it is diluted with water in this way, the solution can be used to soften human skin.
Glycerin previously came primarily from the candlemaking industry rather than from the soapmaking industry, states wiseGEEK. Candles were made from animal fats, so they produced glycerin just as soapmaking did.
It is fairly complicated to remove glycerin from soap, explains wiseGEEK. Soap is made out of fats and lye. The fats already contain the glycerin, and when combined with lye, the result is chemically separate soap and glycerin, though they are still combined in the same mix. From this point, there are various different, complex methods of removing the glycerin from the soap.
Glycerin is used for more than moisturizing, notes wiseGEEK. It is also used for nitroglycerin, which is a chemical component of explosives such as dynamite, and for preserving fruits. It works as a lubricant, is used for printing inks, and sometimes helps preserve scientific specimens.