Penetrant testing is a quite sensitive test method for detection of surface defects. Small crack openings or surface pores can be visualised.

The sensitivity can be enlarged by use of a developer (e.g. deposition or electrostatic spreading).

Indications are enlarged using colour contrast penetrant testing. Therefore they are easily recognisable.

Penetrant testing can be applied for all metallic and non-metallic materials, which surface is well wettable and not excessive porous. Also should the test product not affect the test specimen, means the material should not corrode.

In case of doubt the methode must be tested (for example by corrosion testing according to EN ISO 3452-2).

With penetrant testing finest material separations which are open to the surface can be detected:

Application of penetrant testing is regulated by the international standard series EN ISO 3452. Further technical regulations are SAE AMS2644, ASTM E1417 and ASTM E1418.

Process steps of Penetrant Testing

1. Pre-cleaning:

Removal of impurities and drying of test surface



2. Penetration:

Application of a colour contrast  (or fluorescent) penetrant



3. Excess removal:

Removal of excessive penetrant and drying of test surface



4. Development:

Application of the white developer



5. Inspection:

Visual inspection of the test surface




GHT focusses on research, development and distribution of test products and test equipment for surface crack testing.

GHT test products are: