The solvent dye refers to dye being insoluble in water but soluble in an organic solvent. Based on the types of the solvents, it can be divided into: (1) A series. It can be dissolved in alcohol dye with bright color and is generally used for dyeing alcohol. (2) O series. It can be dissolved in an organic solvent and grease and is mainly used for the coloring of fats and oils. (3) W series. Used for the specific dyes for wax coloring.