The TQC High Voltage Holiday Detector or porosity test provides accurate detection of pinholes, flaws, inclusions, thin spots and bubbles in a coating. The gauge has been specifically designed to revolutionise high voltage DC testing of coatings, making it safer, easier and more reliable than previously possible.

The high voltage technique can be used to test coatings up to 36 mm thick. This method is ideal for inspecting paint on pipelines, tankbottoms and other protective coatings. Coatings on concrete can also be tested using this method.

The instrument has a lot of unique features. A current limiting to avoid coating damage, , and a safety hand grip without sensitive electronics. Extended ribbing on the handle provides an effective barrier between the high voltage and the user. Accurate sensitivity adjustment allows use on metallised or slightly damp coatings.