Glycerin, Pure Glycerin, And Glycerol
Many of the soaps and lotions we use contain some glycerin, though none consist of pure glycerin. The difference between glycerin and pure glycerin is to a large extent a technicality, but there are some important differences between the two.
Glycerol - Pure glycerin is called glycerol. The substance we call glycerin is actually impure glycerol, and there are some differences between pure glycerin (glycerol) and the impure stuff, glycerin. As we know, glycerin is a desirable component of many soaps due to its moisturizing capabilities, and is considered to promote healthy skin because of these moisturizing effects. One would think that the more glycerin one would find in a bar of soap, the more moisturizing it would be. We can't make a soap containing too much, since glycerin is a liquid. Also, if there is too much glycerin in a bar of soap, it will sweat or bead, since glycerin absorbs water from the air. A dish of pure glycerin, left to sit for a time, would eventually turn into a solution of 80% glycerin and 20% water.
Glycerin is a natural product in any soap that has been manufactured from animal fats. Soap producers will often remove much of the glycerin from the soap they are making, leaving more glycerin in the lower priced soaps, and less in the high end products. This doesn't necessarily seem to make sense, but the manufactures have their reasons.
Moisturizes And Dries - If it were possible to manufacture a soap that was essentially pure glycerin, one would think it would be the ultimate moisturizing cleanser. The problem is, glycerin has such powerful hygroscopic qualities, meaning it absorbs water so readily, it would actually serve to dry the skin. A low concentration of glycerin, or glycerin dissolved in water, can have a definite moisturizing effect on the skin, while a high concentration of glycerin, while seemingly moisturizer the outer layers of the skin, would suck moisture from the inner layers of the skin, actually drying the skin from the inside out, and damaging it in the process.
It is therefore possible to understand why soap makers would not produce pure glycerin products, and instead limit the amount of glycerin used in their products. The soap makers really have it both ways, as they can boast that some of their moisturizing products contain a fair amount of glycerin, usually the clear soaps, while other of their products contain a minimum of glycerin, both selling points! One of the reasons why the high-glycerin soaps often sell for less is that they dissolve in water much more rapidly than does the typical bar of soap, and for that reason cannot command too high a price. High glycerin soaps contain on the average 15% to 20% pure glycerin.
The Greeks Have A Word For It - Glycerin, and pure glycerin, is usually defined as being a clear colorless liquid, having a syrupy consistency, and a sweet taste (it also has culinary uses). The name comes from the Greek, glykys, which means "sweet". The chemical composition of pure glycerin is C3H5(OH)3, the OH identifying it as an alcohol.
Many, Many Uses - For most of us who are consumers, the distinction between glycerin, pure glycerin, and glycerol does not usually have a great deal of meaning. The term glycerol is unfamiliar to most of us, and we would only be apt to purchase pure glycerin if we had a particular purpose in mind. In most instances, it is simply the concentration of glycerin in a particular product that counts, and not even the concentration is always of importance. If a soap or lotion contains glycerin, we will likely purchase it. All we really care about glycerin , is it is good as a moisturizer, a suppository, a component of nitroglycerine (for explosives or heart attack pills), has many pharmaceutical uses, is used in making candy, is used in preserving canned fruits, and makes a very acceptable, and non-toxic, antifreeze.