I have to play my ghost-buster role again, this is why herewith I am spreading my passion driven words, this time about the poor glycerine, which was recent, by some giant mind and spirit, accused to dehydrate the skin!!!!!!!!!!!! And therefore of course also my glycerine containing beautiful formulas were declared to be dehydrating products as well.
The following is a short summary of what there is to know about glycerin (glycerol, glycerine – because as we all know; they are the same compound, but different names!);
Glycerol is a 3-valent sugar alcohol, meaning it contains three hydrophilic hydroxyl (aka alcohol) groups. As a result, it is strongly hygroscopic, formed from the enzymatic decomposition of natural fats and oils (triglycerides). It is a subunit of the skin’s natural moisture-retaining factor.
It is included in cosmetic products -among others- for its moisturizing properties, where its proportion doesn’t exceed 8-10%, as is taught even in the most basic cosmetic training, so we’re taking this to come as self-evidence to any professionally trained cosmetician.
Glycerol is manufactured either by saponification of natural oils, (here I’d like to refer to my publication explaining the manufacture of TD™ soaps in detail) or by industrial organic synthesis. We use the former method to obtain the glycerol from palm (let us not get into the issue of the destruction of rainforests for oil palm plantations here, please!) or coconut oil.
I must note that any attempt to differentiate the two products chemically is completely unprofessional and, as such, pointless. The only legitimate consideration is the purity of the substance, be it of a plant, animal (for example pig’s fat, such as in the case of 19th-century candle manufacturing, when most candles were made from this material), or indeed synthetic origin.
Glycerol is a molecule occurring naturally in human cells (it is a metabolic product). One of its major purposes is to transport water between cells, thanks to its hygroscopic nature.
As a result of its hygroscopic properties, it follows that in large amounts it absorbs water, hydrophilic alcohols all do, they need water. This property, however, isn’t an issue in crèmes/lotions, since logically this doesn’t happen at the expense of the skin’s water content, as anyone will know -from their cosmetic studies, if nowhere else- that these oil in water (O/W) type emulsions must contain 75% water on average, at which ratio the glycerol-containing preparation will by no means absorb water, but on the contrary, be strongly moisturising from the viewpoint of the skin. It will however absorb water strongly from the emulsion, and this is exactly where the point of the issue lies, not to mention its ability of bind water and its effect on the barrier function, meaning it has a beneficial effect on evaporation as well.
We also don’t have to worry about which place of the INCI list it occupies -especially in a base preparation, where there aren’t other active ingredients to take over. As mentioned above, the emulsions are generally formulated as 75% water plus the oil-based phase and the indispensable emulsifier, so even with its proportion of 8-10%, it can still be at the front of the list, as such this approach also skews the picture greatly, not to mention its very limited scientific background.
One further addition: certain drinks aimed at sportspeople contain glycerol, as it is a proven fact, substantiated by extensive literature in sports science and related fields, that athletes who have consumed glycerol containing drinks will suffer a smaller degree of fluid loss during extreme exercise. This is no insignificant factor with regards to performance, which furthermore causes, as a logical consequence of reduced fluid loss, a smaller increase in body temperature and heart rate.
Thank you for your attention, I hope you will find the above useful.