
Optical brighteners or optical brightening agents are chemicals that are added to plastics, papers, detergents, and textiles for improved reflectance of blue light. Optical brighteners are also known as fluorescent brightening agents or fluorescent whitening agents. They are the chemical compounds that absorb light in the ultraviolet region of the spectrum and re-emit in the blue region by fluorescence. Optical brighteners are primarily used to enhance the appearance of color of papers and fabrics. More than 400 brighteners are available in the color index; however, less than 100 are produced commercially. Addition of high molecular weight polyethylene glycol or polyvinyl alcohol helps improve the performance of optical brighteners. These are hydrophilic water-soluble compounds that are majorly used in laundry detergents.