Inspection and Test Methods for Coating and Lining: Dry Film Thickness

Dry Film Thickness (DFT) inspection is a testing method used to detect the thickness of an arbitrary section of coating or lining.  There is more than one way to test for dry film thickness, but here we will focus on non-destructive inspection of a non-conductive coating or lining using a handheld, battery powered, digital, dry film thickness gauge (eddy-current gauge) on a ferrous or non-ferrous metallic substrate.


Why Choose Dry Film Thickness Testing?

Adequate coating thickness is integral to long-term, long-lasting corrosion protection.  During the coating or lining process, it can indicate whether your coating or lining is currently the correct thickness in line with the specification.

Out in the field, it can indicate whether a coated surface is deteriorating over time and allow engineers to plan in a repair, or even re-coating or re-lining completely.

How Does Dry Film Thickness Testing Work?

The process is relatively simple.  An operative applies the probe of the gauge to the coating or lining.  The probe detects the strength of eddy current induced between a conduction coil in the probe and the metal substrate.  This is translated to the actual thickness shown up on screen.  The probe is then moved and applied again and is repeated the number times desired.

The accuracy of the inspection can be further ensured by calibrating the gauge on a ‘zero’ plate with a shim of equivalent thickness to that of the specified coating / lining.

On higher end thickness gauges, batches of readings can be taken which can offer an immediate average over the entire inspected surface.


  • No-fuss, broad picture paint condition analysis
  • Excellent at detecting general wear beyond corrosion
  • Simple to carry out without extensive specialist training
  • Compatible with digital systems, Bluetooth, Bluetooth, WiFi, etc.


  • Potential for limited inspection due to inadequate access.

Find Out More

KUE Group offer dry film thickness inspection as part of our services. We specialise in surface preparation, coating and lining. Get in touch today to learn more about what we do.


Request A Quote - Steel Surface Preparation, Linings & Coatings