Which of the following is a method for measuring dry coat thickness?

Measuring dry coat thickness is crucial in ensuring that coatings applied to surfaces meet specified requirements for performance and durability. Magnetic gauges are specifically designed for this purpose, as they utilize the principles of magnetic induction to measure the thickness of non-magnetic coatings applied over magnetic substrates, like steel. This method provides direct and accurate readings of the dry film thickness, making it a common choice in the industry.

Visual inspection, while useful for assessing surface appearance and coverage, cannot provide an accurate measurement of the coating's thickness. Ultrasonic testing is primarily used for measuring thickness in materials, particularly metals and other solid substrates, and is not used typically for coatings. Moisture meters can assess the moisture content in materials but do not measure the dry thickness of a coating.

Thus, magnetic gauges stand out as the most appropriate and reliable method for measuring dry coat thickness, demonstrating their importance in quality assurance during coating applications.