Penetrant testing is a low-cost effective technique available within the section here at CERN in which a materials flaws which would otherwise not be visible to an operator, can become clear through the application of a low surface-tension fluid.

The principle of this procedure depends on this low surface-tension fluid’s interaction with all non-porous materials including:

• Metals
• Polymers
• Ceramics

For metals, both ferrous and non-ferrous materials are compatible with this technique.

The low-tension liquid relies on capillary action as it covers surface breaking discontinuities. This procedure consists of four steps which are outlined below:

• Specimen surface cleaning using solvents etc. This is to ensure no dirt, grease or residue cover any defects or cause any false defect indications when the liquid is applied.
• Application of the penetrant. This is applied either through soaking or spraying. A dwell time is provided accordingly depending on the size of the discontinuities being sought.
• The excess penetrant is removed appropriately depending on the nature of the penetrant. Usually done with the application of water and a clean cloth lint.
• Finally sprayed with a revelatory/developer to reveal these small defects upon the surface of the specimen.