Basic Brown 4, also known as Bismarck Brown G, is a versatile Triarylmethane dye that produces a deep, reddish-brown colour. Similar to Basic Brown 1, it has a strong affinity for anionic materials, making it highly effective for industrial colouring. It is a staple in the leather and paper industries and is also used to formulate inks and stains where a rich, reddish-brown is desired. Its high colour strength makes it a very economical choice.