What is a cosmetic made of?

The composition of cosmetic products is crucial in order to make claims of benefits. There are thousands of formulas on the market, each offering different combinations of ingredients, grouped in the INCI list. However, certain key compounds are typically found in the vast majority of products for skin care, hair care, deodorants, make-up, and creams and lotions.

Solvents.

Solvents play a crucial role in cosmetic products. They are liquids used to dissolve solid ingredients, mix with other liquids, and act as a carrier. They can contribute to the stability, texture, sensory experience, and viscosity of formulations. The solubility of an ingredient in a solvent depends on its polarity. There are three types of solvents: polar, semi-polar, and non-polar. The list below is not exhaustive.

• Polar solvents can form hydrogen bonds. They generally dissolve polar solutes. Examples of these are water and glycols. The water is the foundation of almost all these treatments.

• Semi-polar solvents do not form hydrogen bonds. They can dissolve both polar and non-polar substances. Examples include alcohols, acetone, and esters.

• Nonpolar solvents only dissolve nonpolar molecules. These include oils, such as mineral oils and vegetable oils, silicone oils, hexane, toluene and dimethyl ether.

It is important to understand that the selection of the solvent in cosmetics typically depends on the types of ingredients in the formulation, the galenic form, and the compatibility with the application surface.

Surfactant agents (tensioactives).

These are active ingredients that enhance the blend between two immiscible phases, such as water and oil, by reducing the surface tension between these two phases. Their chemical structure is composed of a hydrophilic head ("water-loving") and a hydrophobic tail ("water-hating"). This structure allows them to dissolve both in water and in oil.

Surfactants are intriguing for the process ofemulsification. Examples would include lecithin, the xanthan gum or beeswax. When the surface is saturated, they will form micelles in the aqueous phase, useful for cleaning products such as shampoos that will trap dirt inside these micelles.

Preservatives.

Preservatives are used in cosmetics to prevent or slow down the growth of bacteria and fungi, in order to maintain the integrity of the product. The activity of water is one of the main factors in determining the quality and safety of a product.

However, the addition of preservatives is often necessary to optimally maintain the stability of the product, which will act against the proliferation of microorganisms. For instance, there are parabens, cationic surfactants, alcohols, and phenolic derivatives.

Thickeners.

These ingredients can increase the viscosity of cosmetics, and can also enhance the stability and applicability and alter the appearance of the product. Overall, there are two types of thickeners.

• Aqueous thickeners, which are used to create viscosity in the aqueous phase of a cosmetic product. Examples include gums and hydrophilic clay.

• Non-aqueous thickenersare used to thicken the water-insoluble phase of a product. They can be found in anhydrous cosmetics (lipsticks). Among others, these include waxes and long-chain alcohols.

• Mineral Thickeners : Also natural, they operate on the same principle previously mentioned. They too absorb water and oils to increase the viscosity of a skincare product.

Magnesium sulfate is a viscosity control agent that allows for the increase or decrease of the viscosity of Typology skincare products.

Antioxidants.

Antioxidants provide protection against free radicals and preserve the oxidation of other molecules. They can be used to prevent or delay the rancidity of oils, fats, butters, and waxes, improve the physical stability of cosmetic formulations, and slow down skin ageing caused by oxidative mechanisms, including oxidative stress.

Their function is to trap or neutralise free radicals produced in response to oxidative stress (pollution, tobacco, UV rays) through various mechanisms, including the capture of singlet oxygen. For instance, we find thebutylated hydroxytoluene (BHT), thebutylated hydroxyanisole (BHA) and propyl gallate.

Dyes/Pigments.

Pigments and dyes are predominantly found in makeup products such as foundations, concealers, lipsticks, or tinted creams. They can be at the heart of the expected benefit or contribute to the consumer experience and the attractiveness of a product, by bestowing upon it a specific colour that will spark interest in the consumer.

Pigments can originate from several sources: mineral (rocks and soils such as ochre or precious and semi-precious stones), organic (derived from living matter such as beetroot, flowers), metallic (acting as small mirrors derived from bronze, copper...etc), and chemical (composed of elements like carbon, zinc oxides, titanium dioxides, cadmium sulphide or even iron oxides to achieve all the desired shades).

Active Ingredients.

Finally, the active ingredients are the compounds that give the products their benefits. They are responsible for the desired effectiveness. Emollients to soften and smooth the skin, moisturisers, humectants, UV protectors, brighteners, firming agents, regenerators, antibacterials... Active ingredients can come from various sources: mineral, organic, chemical. Today, in order to align with the "green chemistry" approach, an increasing number of cosmetic products derive their active ingredients from plants and other botanicals as "botanical extracts" in the form of vegetable oils, plant powders and essential oils.