Dye Penetrant utilizes assorted dyes, blotting and capillary action to detect defects open to the surface. The capillary action draws the dye into the defect, once the defect has absorbed the dye the dye on the surface is removed via solvent, water or wiping. After cleaning a developer (Blotting agent) is applied. The blotting agent draws out the dye from the defect to form an indication on the surface. This technique can be applied to most nonporous materials including carbon steel, cast iron, stainless steel, aluminium, brass copper, Perspex even glazed pottery. It is commonly used on stainless steel welds, castings and motor vehicle parts. The technique can be adapted easily to large assembly lines.