What is an oil in cosmetics?

An oil is a fatty substance that is liquid at room temperature. Vegetable oils and mineral oils are used in cosmetics for skin and hair care. Their production processes and compositions are very different.

Obtaining the oils

Mineral oils

Mineral oils, derived from hydrocarbons, are the result of petrochemicals . They are obtained by distillation of coal, petroleum or shale. This category includes liquid paraffin (called paraffinum liquidum or petrolatum) or silicones (siloxanes, for example, are widely used in cosmetics). These fossil oils are odorless and colorless.

Vegetable oils

Vegetable oils are mainly derived from fruits or plant seeds . There are several processes for extracting vegetable oils:

• Mechanical processes provide a so-called "  virgin  " vegetable oil which retains a characteristic odor and color linked to its composition. The three mechanical processes are:
  • Cold pressing;
  • Cooking at moderate temperature (below 40°C) followed by pressure;
  • La centrifugation.
• Solvent extraction which  degreases the crushed seeds. This method is followed by distillation to remove the solvent.
• Refining which produces an oil without odor or color but very denatured .

Oily macerates

Some vegetable oils are actually oily macerates. This maceration technique is used when mechanical extraction processes are not possible.

The part of the plant of interest (such as St. John 's wort flowers for example) is then left to macerate in an oil from another plant species (olive oil for example). Monoi is another example. This Polynesian recipe corresponds to a maceration of tiare flowers in a coconut vegetable oil.

Vegetable oils, mineral oils: which should you choose?

Whether mineral or vegetable, oils applied to the skin or hair form a lipid film (fatty film) that prevents water from evaporating. They thus promote hydration , and have an emollient power , that is to say, they soften the skin tissues.

Despite these common properties, the respective compositions and virtues of mineral oils and vegetable oils are very different.

The nutritional contribution of oils

Mineral oils are generally well tolerated by the skin and are very stable, meaning they do not go rancid. However, they do not provide any nutrients to the skin. They also have a negative impact on the environment. Mineral oils, which are derived from hydrocarbons, are not biodegradable. Their production method releases greenhouse gases into the air, as well as many atmospheric pollutants. There is a risk of soil and water pollution from the oil industry.

Vegetable oils are full of nutrients that help nourish the skin and ensure the proper functioning of the skin barrier:

• many essential fatty acids (omega 3, omega 6, omega 9, etc.);
• vitamins (A, E, K, and sometimes B) and other antioxidants (polyphenols, flavonoids, etc.) ;
• of plant sterols .

Their protective antioxidant properties fight against aging and loss of skin elasticity.

Choosing your vegetable oil

Always choose virgin vegetable oils , and if possible cold-pressed . Low-temperature mechanical extraction processes respect the initial composition of vegetable oils.

Choosing an organic vegetable oil ensures you a quality raw material from organic farming while avoiding traces of pesticides. In addition, an untreated plant must defend itself more against infectious agents and pests: it is likely to synthesize more nutrients. 

Use oils to enhance the body and hair

To enhance the body and hair, a few drops of vegetable oils are enough to give the skin and hair a luminous appearance without making them too greasy. It's up to you to find your favorite formula!

Pure or mixed vegetable oils

Vegetable oils each have a particular texture and benefits. They can be used pure , but also in a mixture . This way, you can reduce the oily appearance of an oil, or increase the nutritional value of the oils for local applications on the skin of the face or body, nails and hair.

Face and body care: which oil for which skin type?

Depending on their textures, certain vegetable oils are more suited to certain skin types:

• Oily or acne- prone skin : More penetrating oils are preferred. With their fine textures, they penetrate the pores of the skin more easily. The lipid film on the skin's surface is less greasy and less shiny. This is an example of apricot kernel oil ( Prunus armeniaca ). You can also opt for jojoba oil ( Simmondsia chinensis ). This highly penetrating liquid vegetable wax is the one that most closely resembles the sebum naturally secreted by our skin.

• Dry skin  : Most oils can be suitable for dry skin, including the more penetrating oils on top. Some are more nourishing than others. Argan oil ( Argania spinosa ), for example, is very nourishing, regenerating, firming and prevents skin from drying out. Sweet almond oil ( Prunus amygdalus ) can be suitable, but especially for the body because it is a little less penetrating and can give an oily appearance on the face.

• Mature skin  : Borage oil ( Borago officinalis ) is a very antioxidant oil with anti-aging properties. Regenerating, it fights against aging. For its firming properties, apple seed oil ( Pyrus malus ) is ideal for tired, mature and dehydrated skin.

• Skin exposed to the sun  : Nourishing, monoi is also soothing. It is often used as an after-sun.

Feel free to mix these different vegetable oils to obtain a formula that suits you perfectly. To make an argan oil more fluid, you can mix it with a more penetrating vegetable oil like apricot kernel oil!

Hair care

Many vegetable oils have a restorative effect on damaged, dry or dull hair . They tighten the scales of the hair fibers, nourish the hair and scalp, unify and illuminate the hair. We will choose in particular:

• monoi;
• argan oil ( Argania spinosa );
• borage oil ( Borago officinalis );
• apricot kernel oil ( Prunus armeniaca );
• sweet almond oil ( Prunus amygdalus ) especially for irritated scalps.

For oily hair and scalp , jojoba oil ( Simmondsia chinensis ) is more suitable.

Pure or mixed oils should be applied as a mask to the hair. Since the oily appearance does not suit everyone, you can apply the mask in the evening and leave it on overnight before shampooing.

Vegetable oils for massages

Some oils are ideal for massages because they are not absorbed too quickly by the skin. They lubricate the skin for several minutes and allow for easier massage by avoiding friction. This is the case for sweet almond oil ( Prunus amygdalus ), apricot kernel oil ( Prunus armeniaca ) or argan oil ( Argania spinosa ). The skin tissue benefits from their emollient and nourishing power.

Vegetable oils are the most suitable vehicle for diluting essential oils . On the advice of a health professional trained in aromatherapy, you can thus perform well-being massages. 

Regenerating vegetable oils

Calophyllum vegetable oil ( Calophyllum inophyllum ) is regenerating, softening and soothing.

Thick, sweet almond oil ( Prunus amygdalus ) also has softening and moisturizing properties and is known to be the most used oil in children.

St. John's wort ( Hypericum perforatum ) oily macerate is traditionally used to soothe skin irritations and relieve itching. Be careful not to expose yourself to the sun after applying this photosensitizing oil!