Inexpensive dark blue inorganic pigments, which are widely used in coatings and printing ink industries, and do not produce color bleeding. In addition to being used alone as a blue pigment, it can be combined with lead chrome yellow to form lead chrome green, which is a commonly used green pigment in paints. As it is not alkali resistant, it cannot be used in water-based paints. Chemicalbook also uses iron blue in carbon paper. In plastic products, iron blue is not suitable for use as a colorant for polyvinyl chloride, because iron blue degrades polyvinyl chloride, but it is suitable for the coloring of low-density polyethylene and high-density polyethylene. In addition, it is also used for the coloring of paintings, crayons and painted varnished cloth, lacquer paper and other products.