Penetrant testing (PT) is one of the oldest and most widely used methods for the detection of surface discontinuities in nonporous solid materials. The earliest tests with the oil and whitening method were performed in the late 19th century and were primarily dedicated to the examination of various railroad parts, such as the rails, axels and shafts.
From mid 20th century, the penetrant method has gone through a remarkable development and is now the most important method for the detection of surface defects and discontinuities.
Penetrant testing will help you find defects that are open towards the surface, like cracks and pores. The method is suitable for all non-porous materials such as steel, aluminium, copper, plastics, ceramics and castings. The method is relatively simple to carry out and is very applicable depending on its portability. It is a high sensitivity method that is also effective for production inspection.
Liquid penetrants can be divided into two main categories: colour contrast penetrant and fluorescent penetrant. They can further be classified according to the way excess penetrant is removed and the denomination of the developer.
Liquid penetrant method
• Will detect discontinuities open towards the surface in non-porous materials
• Is a high sensitivity method for the detection of very small defects like cracks and pores
• Relatively simple, versatile, reliable and inexpensive.