Ci
CI 42090 (Blue 1)
CI 42090 · Blue 1 · Blue 1 Lake
A water-soluble synthetic blue color additive (a triphenylmethane dye) — present to color the formula, not to do anything to the skin.
What it does
CI 42090 is the colorant code for Brilliant Blue FCF, a synthetic triphenylmethane dye approved by the FDA as FD&C Blue No. 1. In a skincare formula it serves one purpose: visual color. The water-soluble dye form colors the liquid phase; the "Lake" variant is the same chromophore bound to an aluminum substrate so it can be dispersed in oil-phase or anhydrous formulas. Either form contributes only color — no documented skin-care effect.
Also known as
blue 1, brilliant blue fcf, fd&c blue no. 1, acid blue 9
This page is public and indexed on purpose (unlike profiles and drops, which are unlisted) — it’s the citation behind shared ingredient cards, and it should be findable.
Want more like this?
Get Drop, free. Every flag cites its source, the app tells you when your routine is complete, and it helps you simplify — instead of selling you more products.