The color of a tackifier resin is determined by the initial color of the feedstocks and the degree of hydrogenation used. The importance of color is dependant on the application. For example, the required standard in the medical industry is water-white (colorless) because it implies high quality and cleanliness. When a tackifier resin is used in a brown pigmented pressure sensitive adhesive or in applications where the adhesive will not be seen by the consumer, the color of the resin is not as critical.
Tackifier resins can be made from crude raw materials that produce highly colored, but low cost products, or from highly refined pure monomer feedstocks that produce low color products with significantly higher costs. Color can also be improved through hydrogenation. Eastman's line of Eastotac™ resins (hydrogenated, C5) have different degrees of hydrogenation and color, and are differentiated by E, R, L, and W type designations.
Colors of commercially available resins (typically found on a sales specification) range from dark brown to yellow to colorless (commonly called water-white), and vary in intensity, shade and hue. The trend toward lighter colored resins is a result of the perception that they are of higher quality.
Figure 1: Color Scale Correlation Chart