Denim expresses color by adjusting the thickness and thinness by the difference in the concentration of the bleaching solution, but the bleaching with a deep concentration is bleached close to white, giving it a clear, light, and bright feeling. At this time, softness, brightness, and comfort can be expressed by repeating the concentration of the bleaching agent lightly several times while the denim is sufficiently wet. In addition, if instantaneous heat treatment is performed at the time of decolorization, it can be shipped and strongly decolorized due to vaporization. That is, it can represent the fast, slow, and phenomenon of time. Discoloration by spraying, spraying, or blowing with a bleaching agent whose concentration has been adjusted may also indicate anxiety and dizziness.