Chemical Stability

Resin, crosslinking agents, UV-initiators, and any other additive may react with the pigment and alter its performance. At the time when UV-cured coatings were new to the market, additives significantly reduced storage stability, causing the coating to gel in the can. A great deal of care must be taken when selecting pigments for powder coatings, as the initiator can change the pigment shade and reduce fastness properties. Reputable pigment manufacturers publish data on such systems and can often offer assistance in the case of difficulties.

Another adverse effect can come from chemicals that the coating gets in contact with. Water, in the form of condensation, can seriously affect a paint film, particularly in bathrooms and kitchens. Many of the detergents used for cleaning paintwork are harsh and have an abrasive affect upon the pigment. Should the coating come into contact with food, it is essential firstly, that the coating is unaffected and secondly, that the food remains unchanged.

Many testing processes concerning chemical stability consist of applying the chemical to the surface of the coating, keeping them in contact for a given time, then measuring the discoloration of the coating and/or the staining of the chemical concerned.