In cosmetics, sodium silicate powder is usually used as a buffer, anti-caking agent, etc.4. Its index requirements are generally as follows:
Chemical composition
Sodium oxide (Na2O) content: generally required to be between 25.5%-29.0%.
Silicon dioxide (SiO2) content: usually required to reach 49.0%-53.0%.
Modulus (M): Modulus refers to the molar ratio of silicon dioxide to sodium oxide, generally 2.00±0.101.
Physical properties
Appearance: should be colorless or slightly colored transparent or translucent glass-like particles or powder
Particle size: The particle size of cosmetic grade sodium silicate powder is generally required to be finer, and usually has certain requirements on the mesh number, such as 20-40 mesh, etc., to ensure its dispersibility and solubility in cosmetics1.
Density: The density of industrial sodium silicate should be greater than 1.2g/cm³2.
Impurity content
Water insoluble matter: The content should be as low as possible, generally not exceeding 0.04%-0.4%.
Heavy metal content: The content of heavy metals such as lead, mercury, cadmium, arsenic, etc. must be strictly controlled at an extremely low level. It is usually required that the content of each heavy metal does not exceed a certain limit, such as lead content not exceeding 10ppm, mercury content not exceeding 1ppm, etc., to ensure the safety of cosmetics.
Iron content: Too high iron content may cause the color of sodium silicate powder to darken and affect the appearance of cosmetics. Generally, the iron content is required to be no more than a certain value, such as 0.05%.
Stability.
Chemical stability: Sodium silicate powder should remain chemically stable in the common formula environment of cosmetics and is not easy to react chemically with other ingredients to ensure that the quality and performance of cosmetics are not affected during the shelf life.
Thermal stability: During the production, storage and use of cosmetics, different temperature conditions may be experienced. Sodium silicate powder should have good thermal stability and not decompose or deteriorate within a certain temperature range.
Microbiological indicators
Total number of bacteria: Generally, the total number of bacteria in each gram of sodium silicate powder is required not to exceed a certain number, such as 1000 CFU/g, etc., to prevent cosmetics from deteriorating and becoming moldy due to microbial contamination, affecting product quality and safety of use.
Total number of molds and yeasts: It also needs to be controlled at a low level, such as not exceeding 100 CFU/g, etc., to ensure the microbial safety of cosmetics.
Pathogenic bacteria: Pathogenic microorganisms such as Salmonella, Staphylococcus aureus, and Pseudomonas aeruginosa must not be detected to avoid harm to the health of users.
Post time: Jan-11-2025