Liquid Penetrant Testing is a one of basic method among Non-Destructive Testing. This test done on the components such as welding, castings and other automobile components. Liquid Penetrant Testing is specialized in detecting the defects upon the surface which are impossible to detect by our naked eye.

This method is referred by a general principle of liquid i.e. capillary action. In this method we chemical in the form of liquid. The chemicals used are penetrant, developer, cleaner. The penetrant is used to suck into the defects on the surface. The developer is used for blotting effect. The cleaner is used to clean the surface to avoid the oil lubricants dust particles on the surface.

Initially the surface has to be prepared and then to apply the penetrant and need to give the dwell time to suck the penetrant into the defects of the surface. Except the penetrant sucked into the defects excess has to be removed and then by applying the developer we can visualize the defects upon the surface.

The types of defects that we can detect in this method is surface cracks, shrinkages, undercuts, blow holes and pin holes, crater cracks etc.