In some ingredient lists of cosmetic products, we may come across the term "CI 42090". But what is it? Here are the key points to remember about this ingredient.
What is CI 42090?
The CI 42090 is a dark blue synthetic dye, subject to regulation. Indeed, to be approved, this dye must meet purity criteria defined in Commission Directive 95/45/EC. Classified among the triarylmethane dyes, it is also known by other names, such as Blue 1 Lake in the United States or E133 as a food colourant. It is particularly found in shampoos, hair dyes, foundations, mascaras, lipsticks, eyeliners, face powders...
Chemical formula: C37H34N2Na2O9S3.
Molecular weight: 792.84 g/mol.
Solubility: Soluble in water.
Organoleptic properties: Fine or granular blue powder.
How is it designed?
The cosmetic dye CI 42090, of synthetic origin, is composed of salt dissodium of the α-[(N-ethyl-sulfo-3-benzylamino)-4-phenyl]-α-(N-ethyl-sulfo-3-benzylamino-4)-cyclohexadiene-2,5-ylidene) toluenesulfonic-2 acid and its isomer, as well as accessory colouring materials. It is obtained by precipitating 2-formylbenzenesulfonic acid with metallic salts such as aluminium, barium or others.
What is its utility in cosmetics?
The CI 42090 is used in skin and hair care as a dye. It serves to give them a bright blue colour. It can also be mixed with other dyes to produce a wide range of shades and hues.
Is CI 42090 dangerous?
The CI 42090 has been deemed safe for use on skin and hair. It presents no risk. However, it can cause irritation and redness in people allergic to dyes. That's why a patch test of products containing these dyes is recommended.