Reason of White-Blue Indication for Artificial Crack of Fluorescent Penetrant Testing System Monitor Block

The cause of white-blue indication for artificial crack of fluorescent penetrant testing system monitor block is analyzed. Results showed that in the limited imaging time, there is less fluorescent penetrant returning back to the imaging agent powder layer of the block and the yellow-green indication recognized by human eye could not appear. The white-blue display as shown by the overall artificial crack is actually issued by the imaging agent adsorbed on the artificial crack opening.