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Useful information about cosmetic chemistry

This article on cosmetic science is primarily intended to benefit anyone interested in chemist careers but hopefully the Beauty Brains community will find this information useful as well!

Surfactants

It is amazing how little time is devoted to surfactants in college when you consider the importance they play in so many industries.

What are they? Surfactant is a shorter way to say “surface active agent”. These are molecules that have the property of reducing surface tension, thereby allowing oil and water to form stable (temporarily) mixtures.

Examples – Sodium Lauryl Sulfate, Cocamidopropyl Betaine, Glycol Distearate, Ammonium Laureth Sulfate, Polysorbate 80

Why are they used? Surfactants are used for various purposes in cosmetic formulas including

* Detergents – for cleansing
* Wetting agents – for helping formulas spread more easily
* Foaming agents – to produce consumer friendly suds
* Emulsifiers – to create stable mixtures of oil and water
* Conditioning agents – to improve the surfaces of hair and skin
* Solubilizers – to help mix fragrances into water-based formulas
* Preservatives – to keep cosmetics microbe-free
* Special Effects – to improve the look of certain formulas

Where can you learn more? For a quick primer on the subject, see this book on surfactants on Google. For a more general discussion of surfactants, start with the Wikipedia surfactant page.

Emulsions

This topic is related to surfactants and covered even less in college. Yet emulsions are one of the most important types of mixtures / product forms you will encounter in the cosmetic industry.

What are they? An emulsion is a fine dispersion of one insoluble liquid in another. In the cosmetic industry, the most common emulsions are ones in which oil is dispersed in water. To create emulsions, typically a surfactant is also used.

Why are they used? Emulsions are delivery systems for beneficial cosmetic ingredients. These ingredients are often incompatible with water and have undesirable aesthetic characteristics by themselves. The ingredients are mixed with water to create creams or lotions.

Where can you learn more? Look for upcoming articles on Chemists Corner about emulsions, but until then, you can see this on Google for more information. For a more general discussion of emulsions, see this emulsion entry.

Fatty Acids

While much college time was devoted to learning about acid-base reactions and equilibrium constants, very little time was spent looking at the properties and chain length distributions of specific acids. Those topics are much more important to cosmetic chemists.

What are they? As you learned in college, a fatty acid is a carboxylic acid with a long hydrocarbon “tail”. They are typically derived from biological sources and thus have an even number of carbon atoms. The most important fatty acids in the cosmetic industry are those that have between 8 and 22 carbons.

Examples: Lauric Acid, Palmitic Acid, Oleic Acid, Stearic Acid, Behenic Acid

Why are they used? Fatty acids are the basis for many of the surfactants used in cosmetic products. They are derived from natural oils such as coconut, palm kernel, sunflower, wheat germ, etc. They are used for the following properties in cosmetics.

* Conditioning agents – to improve the surfaces of hair and skin
* Thickening – to make thin products more creamy
* Secondary Emulsifiers – to help create stable mixtures of oil and water
* Opacifying agents – to make formulas look more luxurious

Where can you learn more? You can find information about Fatty Acids in the following fatty acid book and a general discussion here.

Silicones

In college an entire course is devoted to hydrocarbon chemistry which is important. But almost no mention is made of silicone compounds and their usefulness in formulating.

What are they? Silicones are compounds that have a molecular backbone of –[-Si-O-]x- surrounded by hydrogens or methyl groups. They are manufactured from silicon dioxide taken from sand or other minerals. They are also known as polysiloxanes reflective of their polymeric nature.

Examples: Dimethicone, Cyclomethicone, Amodimethicone, Cyclopentasiloxane, Silicone oil

Why are they used? Silicones have a number of properties that make them useful to cosmetic formulators. They are amazingly slick, slippery and can make surfaces look shiny. Some applications include

* Conditioning agents – to improve the surfaces of hair and skin
* Opacifying agents – to make formulas look more luxurious
* Shine agents – to increase hair shine and give gloss to skin
* Defoaming agents – to reduce foam in cleansing formulas
* Occlusive agents – to help moisturize skin
* Slip agents – to help skin formulas spread more easily
* Hair detangling agents – to make hair easier to comb

Where can you learn more? There are entire organizations devoted to promoting the safe use of silicones. You can learn some general information about silicone chemistry from the Silicones Environmental, Health and Safety Council of North America (SEHSC). For more specific cosmetic uses see the Dow Corning web page. Of course, silicones will be a topic we explore in more detail later.

Polymers

Polymers are mentioned in college chemistry courses but the focus is on the molecular structure and how to synthesize them. In the cosmetic industry, structure is much less important than polymer properties.

What are they? As you’ve no doubt learned, polymers are macro molecules made up of repeating monomer units. The molecule generally has a long chain backbone with side groups that modify its properties. Homopolymers are made up of a single type of monomer while copolymers have two or more monomer starting units. They can be synthetically derived or obtained from natural sources (then chemically modified).

Examples: [Natural] Polysaccharides, cellulose, starch, xanthan gum. [Synthetic] Polyquaternium-7, Polyquaternium-10, PVP

Why are they used? Polymers can be used to create a full range of effects in cosmetics. They can be used as thickeners, conditioning agents, formula stabilizers, styling ingredients, and even preservatives. The following are some examples but do not represent all uses for polymers.

* Thickeners – to modify the viscosity of a formula
* Formula Stabilizer – to help keep emulsions stable
* Conditioning agents – to improve the surfaces of hair and skin
* Opacifying agents – to make formulas look more luxurious
* Preservative – to prevent microbial growth
* Occlusive agents – to help moisturize skin
* Styling agents – to hold hair styles in place

Where can you learn more? For a general refresher on polymers, the Wikipedia polymer entry is good. For something more specific to cosmetics, see Principles of Polymer Technology in Cosmetics and Personal Care.

Skin Biology

You may have taken some biology courses but unfortunately, there are so many topics to cover like genetics, biochemistry, evolution, and classification systems, there is almost no time to go into specifics of human biology. Even in your human anatomy classes, the topic of human skin is only briefly covered. We can’t cover everything here but from a cosmetic standpoint, here are some important facts to consider.

1. Skin is made up of two layers – Dermis (inner layer) & Epidermis (outer layer)
2. As skin grows, cells in the epidermis die off and are pushed to the surface by new cells created in the dermis.
3. Dead skin cells are eventually shed and flake off.
4. The less moisture there is in the outer layer, the dryer skin feels
5. Skin products are designed to keep moisture in the outer layer and improve skin’s condition.

Of course, there are many more skin topics to cover like acne, age spots, wrinkles, etc. but those will be things to learn along the way.

Where can you learn more? A good starting point is the book Handbook of Cosmetic Skin Care.

Hair Biology

While you might have picked up a few facts about human skin, you were exposed to even less about human hair in your biology courses. Yet one third of the products launched in the cosmetic industry are formulated for hair. Here are the basic hair facts you need to know.

1. Hair is made of keratin protein.
2. Hair has two important layers called the cortex (inner layer) and cuticle (outer layer)
3. The cuticle is responsible for the appearance and feel of hair.
4. The cortex is responsible for hair strength and flexibility

Where can you learn more? You can get a limited preview of a couple excellent books on the subject of hair biology. The Science of Hair Care and Hair and Hair Care.

Microbiology

From a cosmetic science perspective, the most important aspect of microbiology is how to use preservatives to keep formulas microbe-free. The primary preservatives used in the cosmetic industry include parabens and formaldehyde donors. Much has been written decrying the use of these ingredients but they are necessary to ensure the safety of cosmetics.

Chemical Nomenclature

Naming of chemicals is introduced in your first year of college and expanded upon when you take Organic Chemistry. You are taught the proper IUPAC system which allows you to figure out chemical structures from names. Here’s a surprise. Only a tiny fraction of that knowledge will be useful in the cosmetic industry. In this industry, we follow the naming conventions of the INCI. To learn more, you can see this article about making the transition from the IUPAC to the INCI.

Stability Testing

Unless you spent time volunteering for a professor who worked with proteins, you probably haven’t even heard the term stability testing. When you first start out your career, these may be the most common tests you have to run. Stability tests are studies set up to determine what effect storage at different environmental conditions will have on the formula. Samples of your product are put at elevated temperatures, freezing temperatures and exposed to different types of light. This gives an indication of what the product might look like after sitting on store shelves and in consumer’s bathrooms. The formulator’s goal is to always produce long-lasting, stable products.

This is just a brief synopsis of some of the most important cosmetic science topics but hopefully understanding these terms will make you a smarter beauty consumer.

{ 4 comments… add one }

  • Kate G March 14, 2014, 7:30 pm

    This list is amazing, thank you so much! Bookmarked for what I expect to be many future references!

  • Kevin March 14, 2014, 8:08 pm

    Great information. You guys are doing a wonderful job!

  • Ro March 15, 2014, 11:19 pm

    I just want to say that i love you guys. Thanks!!!

  • Stella March 18, 2014, 2:55 am

    First hats off to you guys for this amazing work. Loved the information you have shared here. Very beneficial!!!

    Stella Wilson

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