Penetrant Testing is a non-destructive testing method used to identify surface defects in materials. It involves applying a liquid penetrant to the surface of an object, allowing it to seep into any cracks or voids. After a specified dwell time, the excess penetrant is removed, and a developer is applied to draw out the penetrant from the defects, making them visible. This technique is widely used in various industries, including aerospace, automotive, and manufacturing, due to its effectiveness in detecting flaws that are not visible to the naked eye. It is suitable for a range of materials, such as metals, plastics, and ceramics.