Acid Blue 9, also known as Brilliant Blue FCF, is a water-soluble synthetic blue dye. It is used as food colour E 133 and as a colourant in cosmetics and pharmaceutical preparations. Industrial uses include dyeing wool, silk and nylon, colouring leather and paper, and biological staining. It also colours lavatory fresheners and flushing water. Recorded grades are technical, food and cosmetic. Packaging formats include 1 kg foil bags, 25 kg drums and 500 kg big bags. Food use as E 133 is subject to the applicable food-additive specification and permitted-use conditions. Cosmetic use is subject to the applicable cosmetic-ingredient conditions. Pharmaceutical use requires the applicable pharmacopoeia grade.