CI 77491 or Iron Oxide: Choosing the Colorant Declaration

Colorants are one of the few ingredient categories with two competing naming conventions running at once, and I get asked about this more than almost anything else. Do you write "CI 77491" or "Iron Oxides"? The honest answer is it depends on which one your supplier documentation actually supports and what the specific colorant is, and getting it wrong is an easy way to stall a review.

Two systems, one ingredient

Most inorganic pigments and some organic dyes have both an INCI name and a Colour Index (CI) number. Iron oxide red is INCI "Iron Oxides" and carries CI 77491. Titanium dioxide is INCI "Titanium Dioxide" and carries CI 77891. The CI number comes from a separate international classification system for colorants used across textiles, paints, and cosmetics, maintained independently of the INCI dictionary.

For cosmetics, the INCI name is generally what belongs in your ingredient declaration. The CI number functions more like a precise cross-reference, useful for confirming exactly which shade or form of a pigment you're using when a general name like "Iron Oxides" could describe red, yellow, or black variants.

Why iron oxide is the perfect example

"Iron Oxides" as an INCI name covers a family: red (CI 77491), yellow (CI 77492), and black (CI 77499) are the common ones, each a distinct compound with its own CAS number even though they share the INCI umbrella term. If your supplier's certificate of analysis specifies CI 77491, that tells you which oxide you actually have. Your finished-product ingredient list will typically show "Iron Oxides" as the INCI term, but keeping the CI number on file matters for two reasons:

• It lets you and any reviewer confirm you're using a form that's actually permitted for the intended use (lip products, eye area, general facial use often have different accepted colorant lists).
• If you ever switch suppliers or shades, the CI number is the fastest way to verify you're substituting like for like.

When the CI number becomes load-bearing

For most botanical or single-compound colorants, INCI alone is sufficient. But CI numbers carry more weight in a few situations:

1. Lip and eye products. Colorants approved for general skin use aren't automatically approved for the lip or eye area in every market. The CI number is often the fastest way to check a colorant against a permitted list for a specific use, since permitted lists are frequently organized by CI number rather than INCI name.
2. Lakes and blends. A "lake" pigment (a dye precipitated onto a substrate) has its own CI number distinct from the parent dye. If your supplier sold you "Red 7 Lake," that's a different declaration than the base dye alone.
3. Mica-based pigments coated with oxides. Cosmetic mica products are often mica coated with titanium dioxide and/or iron oxides. Here you may need to declare the full composite, since regulators want to see each functional colorant component, not just "Mica" as a catch-all.

A working reference table

Colorant	Typical INCI name	Common CI number	Note
Red iron oxide	Iron Oxides	CI 77491	Distinct CAS from yellow/black forms
Yellow iron oxide	Iron Oxides	CI 77492
Black iron oxide	Iron Oxides	CI 77499
Titanium dioxide	Titanium Dioxide	CI 77891	Also a UV filter in sunscreen contexts, different regulatory role there
Ultramarines	Ultramarines	CI 77007	Restricted from some mucous membrane uses in various markets
Carmine	Carmine	CI 75470	Natural, insect-derived, common allergen disclosure consideration

Always confirm the specific CI number against your supplier's actual documentation rather than assuming from the shade name alone. Two suppliers' "red iron oxide" should both map to CI 77491, but I've seen mislabeled certificates of analysis, and the only way to catch that is checking the paperwork rather than trusting the product name on the bag.

What to actually put on a Canadian filing

For a Health Canada Cosmetic Notification Form, the INCI name is what belongs in the ingredient field, expressed with a concentration or concentration range. The Cosmetic Ingredient Hotlist governs which colorants are permitted, prohibited, or restricted to specific concentrations or uses, and it's worth checking your exact pigment against the current Hotlist before you file, since colorant rules do get revisited and the safest habit is verifying against the live list rather than a memory of a past filing.

Keep your CI numbers on hand in your formulation records even though the notification form itself asks for the INCI name. When a compliance reviewer or a future you needs to double-check exactly which oxide, which lake, or which coated mica you used, the CI number is the fastest way to remove ambiguity.

This is one of the smaller but genuinely useful things Cosmetic Comply handles automatically: it maps your colorants to the correct INCI name, flags where a CI number is relevant for the intended product use, and screens each one against the current restricted list before your notification goes out.