Holiday testing or Continuity test is a non-destructive test method applied on protective coatings to detect unacceptable discontinuities that affect the integrity of linings such as pinholes, voids, cracks, area of low dry film thickness, inclusion or contaminant in the paint, coating, and lining film. A paint, coating or lining must be applied as a continuous film to perform its intended function. Many of these defects are not seen by the naked eye, but they can be located using holiday / spark test / high voltage holiday test equipment.
Holiday testing includes finding discontinuities in thin coating films, piping and structures, storage tank interiors, buried structures, pressure vessels and rubberized waterproofing on concrete. Industries that use holiday testing include oil/gas, transportation, construction, tank manufacturers, and coatings/inks/adhesives suppliers.