Dye penetrant testing (DPT) is one of the most widely used evaluation methods. Liquid dye penetrant testing can be defined as a physical and chemical nondestructive testing procedure designed to detect and expose surface connected discontinuities in nonporous materials. The objective of liquid penetrant testing is to provide visual evidence of cracks, porosity, laps, seams and other surface discontinuities. It can be used to inspect almost any material, including:

• Metals (aluminum, copper, steel, titanium, etc.)
• Glass
• Many ceramic materials
• Rubber
• Plastics