How to measure to the SSPC PA2 standard


Using a magnetic gage to measure Dry Film Thickness (DFT) is simple. However, understanding the parameters used to comply with PA2 can be confusing.

In our video, BlastOne breaks down the parameters as well as explain how to easily use the Defelsko Positector 6000 DFT gage.

Basic Overview: There are 5 components to understand regarding the parameters involved in PA2

1. Minimum and Maximum thickness specified by the paint manufacturer.

For effective corrosion control, coating manufacturers specify that their coatings must be applied to a specified (minimum and maximum) coating thickness which they will then guarantee and warrant to the facility owner for X number of years. These two numbers are very important. However, some coatings come only with the minimum DFT specification – so if that is the case, only focus on the Minimum DFT.

2. AREAS – your entire project dimensions need to be divided into separate Areas of a minimum of 100 sq ft (approximately 10m2).

NOTE: Beams and girders have varying measurement requirements, but for this insight, general surface area specifications will be explained.




Gage readings are measurements taken by the magnetic instrument. In each AREA inspected there will be 5 randomly choses “Spots” from which to take these measurements. At least 3 gage readings need to be taken in a region no larger than 1.5” (4cm) in diameter. These three readings will then be averaged to establish a SPOT value.


There will be a minimum of 5 SPOTS in any AREA being inspected. These SPOTS are equal to the average value of the gage readings comprising that spot. Spot values are allowed to drift between 80% of minimum DFT specification and 120% of the maximum DFT specification – as established by the coating manufacturer.

Spot Check



The 5 spots in the inspected area will also be averaged to form a SPOT AVERAGE representing the entire Area. This value must conform to the Paint Manufacturer’s Data sheet specification for Minimum DFT and Maximum DFT.

The SSPC PA2 Standards paper.


Download the SSPC PA2 Poster

Use this helpful refrence to assist with your DFT inspections.