Standard · Adhesion, cure and holidays
ASTM D5162
Holiday (discontinuity) testing of non-conductive coatings on metal.
ASTM D5162 finds holidays in new non-conductive coatings on metal. It has two methods:
- Method A: low-voltage wet sponge. It generally suits a total thickness of 0.5 mm (20 mils) or less.
- Method B: high-voltage spark, for thicker films. A film of 0.25–0.5 mm (10–20 mils) may also be spark tested if the voltage is calculated and set correctly and the coating maker agrees.
Setting the spark voltage
The 2024 revision sets the voltage from Paschen's law: 1.5 times the breakdown voltage of air across the measured DFT, plus 1,500 V. At 20 mils that is about 5,600 V. NACE SP0188 uses the same rule. The old rule of thumb of a fixed number of volts per mil no longer applies.
Before and after the test
Test only after the film has dried or cured: solvent left in it can make a conductive path and is a fire hazard. Conductive pigments affect the result. Ground the detector to the substrate, mark each holiday for repair, and test the repair again. Coatings on concrete have their own standard, ASTM D4787.
6 practice items in the members area mention ASTM D5162 (CIP 1: 4 · CIP 2: 2).
Related
Try it in an exam-style question. The free readiness check shows the question style, explains every answer and gives you a dated study plan.
Take the free readiness checkSee the tracksAbout this page
Also published openly: DeFelsko: selecting the high-voltage holiday test voltage.
This page describes the subject of ASTM D5162 in our own words; it does not reproduce the standard. For the full text, buy the current edition from ASTM International. Checked on 2026-10-14; errors go in the corrections log. CoatMentor is an independent study aid. It is not affiliated with ISO, AMPP, SSPC, NACE International, ASTM or FROSIO.