The appearance of a product is very important. Plastic products can begin to yellow, giving them a color that negatively affects their appearance and hurts customer appeal. Optical brighteners absorb light in the UV and violet region (340-370 nm) and re-emit that light in the blue region (420-470 nm). This can enhance the appearance by making it appear cleaner, brighter and more white. Optical brightener additives work to brighten the colors of your application to help hide the effects of yellowing.