I just finished reading the excellent book The Joy of Chemistry and in a future post I’ll do a review but while I was reading I began to think about inorganic chemistry. For the most part cosmetics require knowledge of organic chemistry. Inorganic chemistry doesn’t come into play too often.
But fret not, learning about all those p-orbitals and coordination compounds were not a complete waste of your brain. There are still a number of inorganic compounds that are incorporated into cosmetic formulations.
Sunblock. Titanium dioxide and zinc oxide. These materials are used in sunscreen formulations to protect the skin from UV damage. These ingredients also double as pigments in color cosmetics.
Colorants. There are a number of color compounds based on inorganic complexes. Iron oxides, alumina, calcium carbonate, bisthmuth oxychloride and mica are just a few examples.
Thickeners. There are a number of bentonite clays that can be used as thickeners. Also, salts like sodium chloride or ammonium chloride can be used to thicken surfactant formulas.
Acids. Strong inorganic acids like Hydrochloric acid or Phosphoric acid are used to reduce the pH of some formulations.
Bases. To adjust pH up bases are used. Sodium hydroxide is used to create soap and potassium hydroxide is used in relaxers to straighten hair.
Hydrogen peroxide is used to bleach hair and advance the chemical reaction of polymeric hair colors.
Aluminum salts. These compounds are used in antiperspirants to prevent sweating.
Selenium sulfide is a potent anti dandruff ingredient.
Pumice is an inorganic compound used as an exfoliant.
Silica is added to cosmetics as a filler material that can extend color cosmetic colorants and provide slip.
Compressed air. One of the ways that aerosols are made is by using compressed air. That means nitrogen, oxygen, hydrogen and the rest of the inorganic compounds found in air are used.
And of course the most common inorganic ingredient used in cosmetics is water.
Knowing organic chemistry is a key part of your cosmetic science background but don’t ignore inorganic chemistry completely. It’s still an important part of formulating.