Oily raw materials are used in large quantities in cosmetic formulations and can exist in three forms at room temperature: liquid, semi-solid, and solid. Generally, oily raw materials that are liquid at room temperature can be referred to as "oils," those that are semi-solid can be called "fats," and those that are solid can be referred to as "waxes." Therefore, oily raw materials in cosmetics can also be referred to as oils, fats, and waxes.

Oily raw materials are used in large quantities in cosmetic formulations and exist in three forms at room temperature: liquid, semi-solid, and solid. Generally, oily raw materials that are liquid at room temperature can be referred to as "oils", those that are semi-solid can be called "fats", and those that are solid can be referred to as "waxes". Therefore, oily raw materials in cosmetics can also be referred to as oils, fats, and waxes.

Cosmetic Raw Material Science Knowledge · The Role and Classification of Oily Raw Materials

The Role of Oily Raw Materials in Cosmetics

● Barrier Function

Oily raw materials can form a hydrophobic film on the skin surface, which reduces moisture evaporation from the skin surface, preventing dryness and cracking, thus protecting the skin barrier and effectively resisting physical, chemical, and biological stimuli from the external environment.

● Moisturizing Function

The basic and important function of oily raw materials is to moisturize the skin, hence they are also known as emollients. Proper use of oily raw materials helps maintain the softness, smoothness, elasticity, and luster of the skin and hair.

● Cleansing Function

According to the principle of similar solubility, using oily raw materials makes it easier to wash away oily dirt from the skin surface.

● Solvent Function

Oily raw materials can act as carriers for certain nutrients and conditioning agents, making the ingredients easier to be absorbed by the skin.

● Emulsifying Function

Some oily raw materials can act as emulsifiers, functioning as surfactants, reducing the interfacial tension of the components in the mixed system during the emulsification process, making the emulsion more stable. High fatty acids, fatty alcohols, phospholipids, and other oily raw materials are commonly used emulsifiers in cosmetic production.

● Solidifying Function

Appropriately adding oily raw materials in cosmetic formulations can also make the product performance and quality more stable.

Classification of Oily Raw Materials

Oily raw materials can be classified in various ways. A common method is to categorize them based on their state at room temperature into solid, semi-solid, and liquid. Solid oily raw materials include stearic acid, cetyl alcohol, beeswax, and paraffin; semi-solid includes mineral oil (petroleum jelly), palm oil, palm kernel oil, coconut oil, and avocado butter; liquid includes olive oil, almond oil, corn oil, polydimethylsiloxane, and dioctyl carbonate.

The sources of oily raw materials mainly include plants, animals, minerals, and chemical synthesis. Among them, plant-derived oily raw materials mainly come from plant seeds and fruits, with some also derived from leaves, bark, roots, petals, and stamens, such as corn oil, olive oil, safflower oil, sweet almond oil, palm oil, and avocado oil; animal-derived oily raw materials include lanolin, beeswax, cetyl alcohol, mink oil, squalane, and turtle oil; common mineral-derived oily raw materials include mineral oil and paraffin; chemically synthesized oily raw materials include silicone oil, silicone wax, and esters (such as caprylic/capric triglyceride, dioctyl carbonate).

Based on different chemical compositions, oily raw materials can be divided into hydrocarbons (alkanes), triglycerides, siloxanes, and synthetic esters. Among them, hydrocarbons (alkanes) are cost-effective and easy to spread to form a transparent film, mainly including iso-dodecane, iso-hexadecane, and polyisobutylene; the vast majority of animal and plant fats belong to triglycerides; siloxane oily raw materials have extremely low surface tension, thus exhibiting better spreadability and film-forming properties, such as polydimethylsiloxane and cyclic polydimethylsiloxane; synthetic esters have good lubricity and a refreshing skin feel, which can be used to reduce the greasiness of other oily components, mainly including caprylic/capric triglyceride and dioctyl carbonate.

Oily raw materials can also be classified based on skin feel into light, medium, and heavy. Light oily raw materials can spread quickly, effectively reducing application time, and provide a strong moisturizing sensation with a lighter skin feel; medium oily raw materials have a longer spreading time and a thicker skin feel; heavy oily raw materials require a longer time to spread and have a stronger stickiness and thicker skin feel.

In addition, the spreadability of different oily raw materials also varies. Oily raw materials that spread quickly, such as light silicone oil, have characteristics of rapid penetration, low greasiness, and a fresh and dry skin feel, providing a relatively short moisturizing sensation; oily raw materials that spread slowly, such as mineral oil, have a slower penetration speed, a more lasting moisturizing sensation, but a heavier greasiness.