Photochromic dyes reversibly alter their color upon exposure to ultraviolet sources or sunlight. These photochromic dyes respond to natural solar irradiation as well as ultraviolet (UV). When sunlight or ultraviolet (UV) radiation is applied, the dye becomes excited and the molecular structure is changed allowing a color to appear. When the stimulus (sunlight/UV) is removed, the dye will return to a state of rest. Photochromic molecules are not reactive in their crystalline state and need to be dissolved in a solvent or polymer to function. These proprietary organic materials come in various activated colors such as: blue, yellow, burgundy and red. When combined, additional colors such as green, brown and gray can be produced. It is possible to combine both fluorescent and/or organic pigments with reversible photochromic to produce permanent colors. 10g--1000g/package.