The Importance of Aliphatic Coatings and UV-Stability
In theory, UV-stable products should have very little loss of gloss or color fade over time, even when exposed to sunlight. On the other hand, non-UV-stable products will first lose gloss when exposed to sunlight, then fade and/or yellow, and, eventually, experience polymer breakdown and coating failure. By definition, aliphatic polyurea coating systems are UV-stable, while aromatic polyurea coating systems are not. What seems pure and simple, is neither pure or simple.
Labels of aliphatic coating products can be deceptive. Although a number of aliphatic systems are truly 100% aliphatic, there are too many aliphatic products out there that are, in fact, blends of aliphatic and aromatic. Some producers will make a blend that is only 51% aliphatic and 49% aromatic and still claim it is an aliphatic product. While there is some argument for this being true, is the customer educated during the purchasing process?
Educate yourself. When purchasing an aliphatic system, ask the producer about the percent of aliphatic materials in their product. Read the product’s Material Safety Data Sheet (MSDS). An aliphatic polyurea coating will contain only IPDI and/or HDI isocyanate (Side A) component. An aromatic polyurea coating uses MDI or TDI isocyanate. Since MDI and TDI are not UV-stable, you should not find either of these components in a truly aliphatic product.