Which of the following is NOT a function of a high voltage holiday detector?

A high voltage holiday detector serves several critical functions in the inspection of coating systems, especially in identifying defects and ensuring coating integrity. However, measuring surface temperature is not one of those functions.

This device primarily detects discontinuities or defects in coatings, often referred to as "holidays" or voids. This is essential for quality control because even small defects can lead to corrosion and failure of the protective coating. The detector applies a high voltage to the surface of the coating, which can reveal breaks in the coating layer that would otherwise go unnoticed.

Additionally, it tests the integrity of coatings by ensuring that a continuous layer is present and undamaged, contributing to the overall effectiveness of the coating in protecting the underlying substrate.

While surface cleanliness is an important factor in the success of an application, high voltage holiday detectors do not assess cleanliness directly. They focus on locating flaws within the coating rather than measuring variables like temperature, which is a separate concern in the coating application process. Therefore, measuring surface temperature is indeed not a function of a high voltage holiday detector.