Today's market presents many choices in coatings for wood. The raw material choice, water resistance, UV protection and durability of a coating should be matched to its intended purpose. Differences in quality can affect the durability and performance you get from products of the same resin structure. Whether the resin used is an alkyd, acrylic or another designation, it is important to realize that these resins can vary considerably in their quality due to the materials, as well as the techniques used to manufacture them. Choosing a higher-quality coating can help avert expensive maintenance and future repairs.
Inert pigments, often called filler pigments, are not all created equal. Fillers are mostly used to occupy volume in a film and reduce the cost of a coating, but they can also impart other desirable qualities. Rheology, gloss and sandability are all attributes that are affected by these inert pigments. For example, calcium carbonate - a commonly used filler - is available in many different grades, with trace differences from various mines that can make a big difference in the coating's performance. Calcium carbonate may react with acid rain to produce frosting on a dark-colored coating. Many fillers also can contribute to chalking, especially if the formulation exceeds the critical pigment volume concentration (CPVC). That's why the choice to use or exclude filler pigments largely depends on the final purpose of the coating.