Ask the Expert Question-and-Answer Archive

by Ron Joseph

February, 2004

Measuring Dry Film Thickness of Powder Coating

Q. We are currently using an ETG film thickness gauge to measure our cured powder thickness. Our paint supplier reccomends that we have 1.5 mills of paint over the peaks of are blast profile. We are using a ETG electronic thickness gauge to measure the dry film thickness of our parts. What I would like to know is ... are we measuring to the peaks, the valleys or an average of the two?

A. The thickness depends on the size of the probe and its relationship with the surface profile. In general, I would say that you are getting an average reading. If this is really important to you and if you need to be certain that you are satisfying your customers, then I suggest that you send me a piece of shot blasted steel that you have already powder coated. We can mount and polish the specimen and then look at it under a microscope to measure actual mil thickness over the peaks and valleys. If you have already measured the film thickness with your ETG film thickness gauge, then we will verify your readings in comparison with ours. If you need a letter to verify this for your customers, then we will write a letter for you and attach photos that confirm out findings. Please let me know if this is of interest to you.