What tool is used to find coating holidays using an electric charge?

The use of a holiday detector is essential for identifying coating holidays or defects in protective coatings applied to metal surfaces, especially in the context of corrosion prevention. A holiday detector functions by applying a low-voltage electric charge to the coated surface. When there is a holiday, or defect, in the coating, the electric charge finds its way through the substrate, allowing the operator to detect the breach.

This tool is specifically designed for this purpose and provides a reliable and efficient means of ensuring the integrity of protective coatings. It is invaluable during the quality assurance phase of coating application, helping to prevent future corrosion problems by ensuring that the protective layer is intact.

In contrast, other options like an ultrasonic tester, resistance meter, and voltage tester serve different functions in testing and measurements. An ultrasonic tester is typically used for thickness measurements and flaw detection in materials, a resistance meter measures the electrical resistance of a path but does not locate defects specifically in coatings, and a voltage tester checks for the presence of voltage rather than measuring the integrity of a coating. Thus, the holiday detector stands out as the appropriate tool for locating coating holidays using an electric charge.