This is strange, since my product itself is white, why do I need to use optical brightener? In fact, a large number of organic materials, natural or artificial textiles or other materials, such as paper, plastic, etc., do not look white, usually they absorb more blue-violet light (400 to 480nm) than yellow light, so they appear more or less yellowish.From the name of optical brightener, we can know that its effect is whitening, rather than dyeing. In other words, the prerequisite for optical brightener to play the whitening effect is that the product itself is white.
Optical brightener is dyed on substrates with certain whiteness (such as textiles, plastics, paper, detergents, etc.) in a way that absorbs the energy of ultraviolet light invisible to the naked eye (about 340~380nm) under sunlight (or light source containing enough ultraviolet light). It is then emitted as a very bright, showy blue-purple fluorescence (about 410~460nm). This blue-purple fluorescence is mixed with the slightly yellow light on the matrix (yellow is a complementary blue-purple color) to obtain white light, and has a whitening effect. Due to the enhanced ability of the matrix whitened by optical brightener to reflect visible light, the whiteness and brightness of the matrix are increased, making the matrix whitened look white, pleasing to the eye and bright. Therefore, it can be seen that the whitening of optical brightener is optical complement brightening, rather than dyeing.