Cationic Stain Blocking Primer Technology
By Greg Monaghan and Alex Pinnix, Specialty Polymers, Inc.
Most water-based architectural stain blocking primers typically have only moderate stain blocking performance, and they are designed to lock stains in the primer coat rather than block stains. This leads to a major performance difference compared to solvent-based primers. Since the stain is visible in the dry film when a bleeding substrate is coated with water-based primer, the painter cannot tell with any degree of certainty if the stain will migrate into the topcoat. Novel cationic water-based primers offer far superior stain blocking and are like solvent-based primers because many stains are blocked by the primer coat rather than locked into the primer coat. For these cationic primers, however, manufacturing procedures and raw materials are different from those typically used in conventional anionic architectural coatings.
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