Iron oxides
Iron oxides suppliers and sourcing guide
Iron oxides are synthetic inorganic pigments made by precipitating and oxidizing iron salts, or by heating iron compounds, to give red (ferric oxide), yellow (hydrated ferric oxide) and black (ferrosoferric oxide) shades. Blending the three gives browns and tans. They are used in supplement tablet and capsule coatings, printing inks, some confectionery and widely in cosmetics, and are sold as powders in food, pharma and cosmetic grades.
- Category
- Colors
- Also known as
- Synthetic iron oxide · E172 · CI 77491 · CI 77492 · CI 77499
- Facts checked
- November 2026
Forms and grades of iron oxides
Suppliers sell different products under the same name. Specify the one you need.
Red iron oxide
Fe2O3 pigment for red, pink and brown shades.
Yellow iron oxide
Hydrated iron oxide, FeO(OH), for yellow and tan shades.
Black iron oxide
Fe3O4 pigment for black and for darkening blends.
Food and pharma grades
Grades with tighter heavy-metal specs for supplement coatings and ingested products.
Coated cosmetic grades
Pigments surface-treated (for example with silicones) for dispersion in makeup.
What to check on the COA
Compare each result with your own specification when the lot arrives.
- Iron content
- Iron oxide assay (as Fe2O3) by titration or XRF, which confirms identity and strength.
- Heavy metals
- Arsenic, lead and mercury by ICP-MS; food grades meet tighter lead limits than cosmetic grades in 21 CFR part 73.
- Loss on drying
- Moisture by loss on drying, which matters most for hydrated yellow oxide.
- Shade and tint strength
- Color compared against a standard by colorimeter, since shade drifts with particle size.
- Particle size
- Sieve residue or laser diffraction, which affects dispersion and specking.
Storage, lots and expiry
Storage and shelf life
Iron oxides are stable; store them sealed and dry to prevent caking, and control dust because the pigments stain. Yellow oxide turns red if overheated, so keep it away from high heat. Shelf life or retest date is set by the supplier specification.
Lots and expiry dates
Record shade against a standard and the iron and heavy-metal results for each lot. Confirm the grade matches the end use, since food, drug and cosmetic listings have different limits.
Regulatory status
Facts from regulators and standards bodies, each linked to its source.
21 CFR 73.200 permits synthetic iron oxide in human food in sausage casings, in candy, mints and chewing gum, and in dietary supplement tablets and capsules including coatings and printing inks.
Source: ecfr.gov (opens in a new tab)For dietary supplements, 21 CFR 73.200 limits use so that elemental iron from the color does not exceed 5 mg per day at labeled dosages.
Source: ecfr.gov (opens in a new tab)21 CFR 73.2250 lists iron oxides for coloring cosmetics generally, including cosmetics applied to the eye area.
Source: ecfr.gov (opens in a new tab)Health Canada's List of Permitted Colouring Agents includes iron oxide (item I.2).
Source: canada.ca (opens in a new tab)
This is general information, not regulatory advice. Status differs by country and by how the ingredient is used, so check the rules for your product and market.
Iron oxides suppliers
Manufacturers and distributors whose own websites say they sell it.
We are checking iron oxides suppliers now
Every listing is checked against the supplier’s own website before it goes live, so this list fills in over the coming weeks. The specs and COA checklist above are ready today.
Sell iron oxides? Request a listingFrequently asked questions
What forms of iron oxides can brands buy?
Common forms include red iron oxide, yellow iron oxide, black iron oxide, food and pharma grades and coated cosmetic grades. Ask each supplier for the specification sheet of the exact grade they quote.
What should the COA for iron oxides include?
Expect iron content, heavy metals, loss on drying, shade and tint strength and particle size, each with its method, specification and result for that lot.
How should iron oxides be stored?
Iron oxides are stable; store them sealed and dry to prevent caking, and control dust because the pigments stain. Yellow oxide turns red if overheated, so keep it away from high heat. Shelf life or retest date is set by the supplier specification.
What is the regulatory status of iron oxides?
21 CFR 73.200 permits synthetic iron oxide in human food in sausage casings, in candy, mints and chewing gum, and in dietary supplement tablets and capsules including coatings and printing inks. For dietary supplements, 21 CFR 73.200 limits use so that elemental iron from the color does not exceed 5 mg per day at labeled dosages. 21 CFR 73.2250 lists iron oxides for coloring cosmetics generally, including cosmetics applied to the eye area. Health Canada's List of Permitted Colouring Agents includes iron oxide (item I.2).
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