C 2635 (OTTO) Crystal violet Cas 548-62-9 - used as a textile dye. C 2635 (OTTO) Crystal violet Cas 548-62-9 - used to dye paper and as a component of navy blue and black inks for printing, ball-point pens, and ink-jet printers. C 2635 (OTTO) Crystal violet Cas 548-62-9 - used to colourize diverse products such as fertilizers, antifreezes, detergents, and leather.