Dye Penetrant Testing (Visible, Fluorescent & Post Emulsification)
Dye Penetration Testing, also known as Liquid Penetrant Testing or Colour Check Testing is most widely used as an NDT method for surface flaws for all type of material. It can also be used as a medium to check for leaks as well in various items. The test area is coated with a visible or florescent dye solution and allowed to soak and dwell on the surface for around 15 mins. The excess dye is removed from the surface, and then a developer is applied. The developer acts like blotter and will draw the dye penetrant out from imperfections that are open and exposed to the surface. Visible dye and the vivid colour contrast between the penetrant and the white developer make the bleed out process easy to view. With fluorescent dyes there is no need to apply a white developer. An ultraviolet lamp is use to exposed a fluorescent bleed-out, thus allowing the imperfection to be seen readily.