Effect of TiO2 Pigment on Gloss Retention: A Two-Component Approach

By Michael P. Diebold

The gloss retention of a coating depends in part on the grade of TiO2 used. Traditionally, the TiO contribution to gloss retention has been attributed to the fact that TiO2 is a photocatalyst, and that gloss retention differences between different grades of pigment are due to different levels of TiO2 photocatalytic activity.

However, there is poor correlation between photoactivity and gloss retention performance. In addition, there is commonly very poor correlation between exterior exposure rankings of TiO2 pigments and accelerated exposure rankings in the same coating.

In this article, we describe a second property of TiO2—beyond photoactivity—that explains these observations and allows us to better predict both exterior and accelerated gloss retention results.