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Answer:
CATALYSTS&CHEMICALS IND.CO.,LTD kindly answered the question.
About iron oxide
 Iron oxides have been one of the most commonly used coloring agents for cosmetics for a long time. People have used iron oxides in natural minerals not only for cosmetics but also for religious ceremonies and skin protection. Manufacturing iron oxides as a coloring agent for cosmetics began around 1900.
Iron oxides have various colors which are classified into three major color groups: the yellow iron oxide (yellow), colcothar (red), black iron oxide (black). These iron oxides are fine powders with a slight unique odor. The following table shows the details of the chemical ingredients of each group. (Attention: each group, especially black iron oxide, does not consist of a single component but instead is a mixture.)
| |
Chemical name |
Chemical formula |
| Yellow iron oxide |
Ferric oxide, hydrate |
FeO(OH) |
| Colcothar |
Ferric oxide |
Fe2O3 |
| Black iron oxide |
Ferrous ferric oxide |
Fe3O4
(Fe2O3/ FeO) |
Color tone depends on the temperature, concentration, pH, and radius of the particle when manufactured. For example, different tones of yellow can be produced from yellow iron oxide using these properties.
At present, iron oxides are the most commonly used pigment for coloring cosmetics such as foundation and eye shadow. Various skin colors are produced by mixing these three groups of iron dioxide in different ratios.
Acknowledgement
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