A universal architectural primer coating serves two main functions. The first is to enhance the ability of a topcoat to beautify the substrate. This is achieved by hiding topographic variations and optical variations. The second main function is adding durability to extend the life of the topcoat. This is primarily achieved by improving adhesion, which can lead to better crack and blister resistance. Enhanced durability is also promoted by the primer forming a barrier layer to improve corrosion, nail rust and flash rust resistance.
Despite the need for a primer to be somewhat of a universal product, the primer market is actually heavily segmented. Critical performance needs include hiding topographic variations, sealing porous substrates, preventing old colors from showing through the topcoat, odor blocking, providing a good tie coat layer between the substrate/topcoat, extending exterior durability, and reducing stains from migrating into the topcoat. Odor-blocking primers typically aim to block persistent odors that come from cigarette smoke, pets and food. Primers are used on a wide variety of substrates such as glossy alkyd, steel, aluminum and wood, so they must demonstrate exceptional adhesion across all surfaces. Primers are also promoted for exterior durability, so it is critical that they demonstrate excellent crack resistance, corrosion resistance and adhesion. Common problematic stains that waterborne primers have difficulty blocking include wood tannins, markers, food stains, water damage and nicotine from cigarettes. From this list alone, it should be obvious why each major manufacturer has at least 10 primer product lines, each targeting a specific need. In addition to these performance needs, the market is further segmented into various label claims including fast drying, multipurpose, stain killing, mold killing and odorless, just to name a few.