Definition - What does Penetrating Primer mean?
A penetrating primer is a substance used as a preparatory coating on a variety of materials such as metal, concrete, wood or canvas. This primer is primarily used to penetrate and bind old, loose coatings and powdery, chalky surfaces to provide a firm, solid base for the subsequent application of additional coating layers. This is especially useful to ensure the efficiency of anti-corrosion coatings.
Corrosionpedia explains Penetrating Primer
Penetrating primers are epoxy-based and possess low molecular weight and viscosity. They are also typically clear or lightly pigmented. These primers are necessary when decorative or protective coatings need to be applied to flaking, powdery, lime washed or otherwise neglected surfaces.
Applying coatings directly to loosely bound and unprepared surfaces can lead to early coating failure due to a loss of adhesion. Additionally, unprepared porous surfaces can absorb or soak up paints resulting in unnecessary multiple coatings. Using penetrating primers to bind the surface before applying subsequent coatings can help to avoid some of these issues.