Liquid Penetrant Testing is used to determine the existence of surface imperfections. The test object or material is coated with a visible or fluorescent dye solution and allowed to remain in contact with the surface for approximately fifteen minutes. Capillary action draws the dye into the imperfection(s) during this period. The excess dye is removed from the surface, and a developer solution is applied. The developer acts as a blotter and draws the dye out of the imperfection(s), to form a visual, magnified in width, indication in good contrast to the background.