Optical brighteners have been used for many years to improve the colour of various plastics. They are able to mask inherent yellowness in discoloured polymers or impart unique, robust colour to speciality plastic products. Daniel A. Jervis of Eastman Chemical Company describes the key properties of two of the main optical brighteners available for thermoplastics and describes how they can be used cost effectively in a broad range of plastics products to enhance aesthetics and consumer appeal.