Database/Hair Dyeing/Acid Blue 9
Mostly petroleum · ISO 16128

Is Acid Blue 9 natural?

Mostly not. Synthetic triarylmethane acid dye. Its sulfonate groups (from sulfur trioxide) and sodium counter-ions count as natural origin under the site's counter-ion convention; the coloured carbon skeleton is entirely petrochemical. Same treatment as CI 16185.

INCI nameAcid Blue 9
CAS3844-45-9
FunctionHair Dyeing
FeedstockPetrochemical aromatic amines and naphthols coupled into the…

How we scored it

Acid Blue 9 (Brilliant Blue FCF, disodium salt) C37H34N2Na2O9S3 792.8 Da: 3×SO3 240.2 Da + 2×Na 46.0 Da are mineral-derived (natural) = 286.2 Da; the triarylmethane chromophore 506.7 Da is petrochemical → 286.2/792.8 = 0.36.
What counts. ISO 16128-2 scores the atoms that remain in the final ingredient. Reagents, solvents, catalysts and protecting groups used during manufacture leave no mass behind and are not counted.

Where it comes from

Petrochemical aromatic amines and naphthols coupled into the dye, sulfonated with sulfur trioxide/sulfuric acid and neutralised with sodium hydroxide.

In plain English

A bright blue synthetic dye used in cosmetics, built from petroleum-derived aromatic chemicals through industrial dye synthesis.

CosIng definition: Acid Blue 9 is classed chemically as a triphenylmethane colour. It conforms to the formula:

Natural alternatives with the same function

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 Dihydroxyacetone 100% natural origin

The active self-tanning ingredient that reacts with skin's surface proteins to produce a temporary bronze colour; made by…

 Epicatechin 100% natural origin

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 Lawsonia Inermis Extract 100% natural origin

A plant extract from the henna shrub, used to condition hair and skin and add a reddish tint.…

 Pyrogallol 100% natural origin

A hair-dye ingredient traditionally made by heating gallic acid, itself extracted from plant tannins in gallnuts, until it…

References

  1. 1ISO 16128-1:2016 and ISO 16128-2:2017 — Guidelines on technical definitions and criteria for natural and organic cosmetic ingredients and products. ISO, Geneva.
  2. 2ACID BLUE 9. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  3. 3ACID BLUE 9. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=ACID%20BLUE%209