This part of EN 623 specifies qualitative methods for determination of the presence of defects in advanced technical ceramics by dye penetration tests. The results are reported as visual observations of dye penetration.Three methods are described:Method A: A fuchsine dye test which is suitable for white or pale-coloured ceramic products, performed using an evacuation test.Method B: A fluorescent dye test which is suitable particularly for those products where the purple fuchsine has insufficient visual contrast with the ceramic material, performed using a proprietary test kit.Method C: A fuchsine dye test which is performed by simple immersion in or spraying with a dye solution, suitable for routine testing for major defects.