PENETRANT TESTING (PT)
The technique of Dye Penetrant Inspection is based on the ability of a liquid to be drawn into a clean surface-braking flaw by capillary action. After a period of penetration time, excess surface penetrant is removed and a developer applied. This draws the penetrant from the flaw to reveal its presence. Colour contrast penetrant requires good white light while fluorescents need to be used in darkened conditions with an ultra violet light (Also known as Black Light).
It is essential that the material is carefully cleaned first, other wise the Dye Penetrant Inspection penetrant will not be able to enter the defect. If surface penetrant is not fully removed, misleading indications will result.