What Does
Pinhole Mean?
A pinhole is a pore-like penetration that is present in paints and coatings due to the entrapment of moisture, air, solvents or other fluids. The presence of pinholes increases the corrosion rate experienced on a surface due to the moisture pockets that cause crevice corrosion, pitting and increased redox reactions.
Corrosionpedia Explains Pinhole
Pinholes are a coating defect (holiday) can be prevented by the use of surface tension reducing agents to transport air bubbles to the surface of a coating.