Behind the dazzling array of cosmetics lies a vast chemical industry. Using modern chemical technology, people can easily and quickly produce sufficient quantities of cosmetics to meet consumer demand. The production of cosmetics relies on the ratio of various chemical raw materials, among which inorganic powders with unique physical and chemical properties play a crucial role, mainly used as colorants and fillers.

Inorganic Pigments in Cosmetics

Cosmetic colorants (or pigments) can be classified into three major categories based on their source: synthetic pigments, inorganic pigments, and natural pigments derived from plants and animals. Based on solubility, synthetic pigments can be further divided into dyes, lakes, and pigments. Dyes refer to substances that can dissolve in water, oil, or alcohols. Depending on the solvent, they are further classified into water-soluble and oil-soluble dyes. Lakes are dyes or pigments that are insoluble in water. They are primarily formed by precipitating water-soluble acidic dyes using metal salts or by adsorbing these metal salts onto water-resistant pigments. Pigments are coloring powders that are insoluble in water, oil, and other solvents. Compared to lakes, they offer superior coloring power, coverage, and resistance to dissolution, and are widely used in cosmetics such as lipstick and blush. Inorganic pigments are primarily categorized into three types: metal and alloy powders, oxide and hydroxide pigments, and other inorganic pigments.

Aluminum powder

Aluminum powder is a silver-gray powder with a relative density of 2.55 and a melting point of 685°C. Pigment-grade aluminum powder generally refers to aluminum powder with a flake-like particle structure and a thin film of fatty acid on its surface.

Copper powder
Copper powder is a red powder with a relative density of 8.92 and a melting point of 1084.5°C. Copper powder used as a pigment generally refers to copper powder with a flake-like structure and a thin film of fatty acid on its surface.

Titanium dioxide
Titanium dioxide can absorb ultraviolet rays, reflect and scatter ultraviolet rays, and transmit visible light. It is a high-performance, highly promising physical shielding type of ultraviolet protection agent. Titanium dioxide used in cosmetics can be adjusted and controlled by selecting different coating methods to modify the properties and effects of the coated nano-titanium dioxide particles.

Zinc oxide
Zinc oxide and titanium dioxide are two important and widely used physical sunscreens. Both can absorb and scatter ultraviolet rays. Zinc oxide has antibacterial properties. Zinc oxide used in cosmetics provides full-spectrum UV protection, excellent dispersibility and transparency, safety, non-irritating properties, and good light stability.

Inorganic Powder Fillers in Cosmetics

Common inorganic powder fillers used in cosmetics include: silica, diatomaceous earth, layered silicate powder fillers, precipitated calcium carbonate, phosphates, and aluminum hydroxide. Among these, layered silicate powder fillers are primarily kaolin, bentonite, talc powder, and mica powder.

Silicon dioxide
There are many types of silicon dioxide. Precipitated silicon dioxide is mainly used in cosmetics. It is a colorless, transparent, shiny crystal and amorphous powder. It is chemically inert, insoluble in water and acids (except hydrofluoric acid), and soluble in concentrated alkali solutions. It is very stable within the pH range used in cosmetics. Depending on its particle size, particle size distribution, and pore volume, precipitated silicon dioxide can be used in different cosmetics.

Diatomaceous earth
Diatomaceous earth has a porous structure, high oil absorption, low bulk density, and high adhesion. As an inexpensive powder filler, diatomaceous earth is mainly used in various powders and powder cakes, as well as in face masks.