Standard · Application and film thickness
ASTM D6132
Dry film thickness by ultrasonic gauge, also on concrete, wood and plastic.
ASTM D6132 covers ultrasonic gauges that measure the thickness of organic coatings without damaging them. Their great use is on substrates where magnetic and eddy-current gauges cannot work: concrete, wood, wallboard, plastic and composites. They also work on metal.
How the gauge works
The probe sends a sound pulse through a couplant into the coating. The pulse reflects at the interface with the substrate, and the gauge turns the travel time into thickness. In a system of several coats it finds the interface with the greatest acoustic difference; some gauges show each layer.
Points to remember
- A couplant is needed for each reading: water on smooth coatings, a gel on rough ones.
- Verify the gauge on reference standards of known thickness.
- Soft coatings that deform under the probe are outside the method. Air voids and heavily filled or flake-filled coatings can give low readings.
- D6132 tells how to take a reading, not how many. SSPC-PA 9 gives the number of readings on non-metal substrates.
10 practice items in the members area mention ASTM D6132 (CIP 1: 2 · CIP 2: 7 · FROSIO written: 1).
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
This page describes the subject of ASTM D6132 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.