Database/Colorant/Pigment Red 172 Aluminum Lake
Mostly natural · ISO 16128

Is Pigment Red 172 Aluminum Lake natural?

Mostly. Mostly mineral alumina carrying a synthetic dye; the alumina substrate makes up most of the mass.

INCI namePigment Red 172 Aluminum Lake
CAS12227-78-0
FunctionColorant · Hair Dyeing
FeedstockErythrosine (Acid Red 51) is made by iodinating…

How we scored it

Lake: the dye is laid on an alumina (aluminium hydroxide) substrate. Dye content varies by grade (often 10-40%); taken as 25% dye on 75% alumina, the same assumption as the other lakes. Alumina is mineral. Dye part, erythrosine aluminium salt: only the aluminium, 18 of 852 Da (its four ring iodines are not mineral salts), natural fraction 0.02. 0.75 + 0.25 x 0.02 = 0.76.
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

Erythrosine (Acid Red 51) is made by iodinating fluorescein (resorcinol plus phthalic anhydride) and is laked with aluminium salts onto alumina. No natural-origin dye route is used, and the result depends on the dye loading and on counting covalent iodine as mineral.

In plain English

A pink-red colour pigment: the iodine-containing dye erythrosine fixed onto aluminium oxide, listed as a colorant and for hair dyeing. The dye core is made from petrochemical aromatics; the iodine and aluminium base are mineral.

CosIng definition: Pigment Red 172 Aluminum Lake is an insoluble pigment composed of the aluminum salt of Acid Red 51 extended on an appropriate substrate. It conforms to the formula:

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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. 2PIGMENT RED 172 ALUMINUM LAKE. CosIng — European Commission cosmetic ingredient database. ec.europa.eu/cosing ↗
  3. 3PIGMENT RED 172 ALUMINUM LAKE. CosIng u2014 European Commission database for information on cosmetic substances and ingredients. https://ec.europa.eu/growth/tools-databases/cosing/search?search=PIGMENT%20RED%20172%20ALUMINUM%20LAKE