chemistry lesson: redox

Hello! I’ve decided to start a new segment on here called chemistry lesson, where I will outline a basic concept of general, organic, inorganic, or biological chemistry and explain it’s connection to cosmetics. First up will be reduction and oxidation – redox for short.

To start from the very beginnings of chemistry, atoms (as far as we are concerned) contain four essential components; the nucleus, protons, neutrons and electrons. The proton (+ charge) and neutrons (neutral charge) are all located inside the nucleus, while electrons (- charge) are located in an electron cloud surrounding the nucleus. Reactions occur due to the interactions and exchanges of protons and electrons between atoms. Reduction-Oxidation reactions take place in almost all fields of chemistry, including general, physical, inorganic, organic and biochemistry.

“OIL RIG” was the basis of how I learned redox chemistry, and I still use this mnemonic today. OIL: Oxidation Is Loss of electrons; RIG: Reduction IGain of electrons.


It is important to remember that because electrons hold a negative charge, when something is oxidized it earns a positive charge which makes it susceptible to undergo undesirable changes. This is the purpose of antioxidants– they prevent the auto-oxidation that often occurs in foods, cosmetics and other such products. (The outline and role of antioxidants will be covered in a future chemistry lesson!)

Now why are redox reactions important in cosmetics? Because cosmetics are expected to hold certain shelf lives, they are created with preservatives and antioxidants to help combat these reactions and undesired changes that take place. In general, reduction reactions are typically beneficial reactions, while oxidation are typically negative.

Positive Redox reactions in Cosmetics:

  • anti-acne products
  • skin lightening
  • teeth whitening
  • hair bleaching
  • hair straightening
  • perm products

Negative Redox reactions in Cosmetics:

  • oxidized foundation – has been linked to acidic and/or oily skin. This process can be noticed when your foundation appears orange
  • oil oxidation – I’m not sure how frequently this happens with cosmetic oils, but it is very common for cooking oils (lipoxygenase reaction). The process involves cloudiness, rancid smells, color darkening, etc. This can simply be avoided by keeping the product in a dark bottle/dark location, having minimal exposure to light and excessive heat.


There is not much research, at least that I was able to access, that shows how highly affected cosmetics are by redox reactions. However, it is important to know how to take proper care of your products in order to keep yourself safe. By following guidelines on the label, using the product by the expiration date, and keeping the product out of direct sunlight, heat or extreme cold, you can keep your products in prime condition.






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