Yellowing of Alkyd resin bound Enamel Paints

The binders used in High Gloss and Eggshell Enamels are called Alkyd resins. Chemically they are (vegetable) oil-modified polyesters. The percentage of oil, and the type of oil used, are responsible for a range of properties that the resulting polymer will exhibit. One of these properties is the amount of yellowing that coatings produced on these binders will show. This is particularly noticeable in white paints. The yellowing occurs faster in dark environments or in areas where cleaning materials containing "active ammonia " are used. Unfortunately there are no additives paint manufacturers can include in their formulations to reduce the level of this occurrence - the raw materials used in the binder production determine this. Alkyd resin manufacturers are, in turn, limited by vegetable oil-supply constraints as well as costs. Often water-based alternatives give better results than traditional solvent-based enamels without yellowing or becoming brittle over time.