What feature in an ultrasonic thickness gauge helps when measuring through coatings?

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When measuring through a coating, the ultrasonic pulse spends part of its travel time in the coating before it reaches the metal and then back again. The coating usually has a different sound speed than the substrate, so if the gauge assumes only the metal’s speed, the result will be off. Coating compensation is the feature that accounts for the coating layer—using the coating’s properties or a calibration model to separate the coating’s travel time from the metal’s. This lets the gauge report the true substrate thickness rather than the combined effect of coating plus metal. Other features like temperature compensation, dual frequency, or base plate calibration help with other issues, but they don’t specifically address the extra time the pulse spends in the coating. That makes coating compensation the appropriate choice for measuring through coatings.