Tap testing an NDT Technique “Tap Test is an old and simple technique to inspect composite materials. Its main objective is to detect discontinuities, especially detachments and delaminations.” Reference : linkspringer . com One of the disadvantages of composite is detecting the damage and its extent. Tap testing is one of the simplest and requires no extra equipment. You mark it in a 10mm × 10mm grid. Coin tap testing involves tapping in a regular manner and listening for a dull or dead sound,