Control of Drying Process
The temperature used to dry parts after the application
of an aqueous wet developer or prior to the application of a dry
powder or a nonaqueous wet developer, must be controlled to prevent
"cooking" of the penetrant in the defect. High drying
temperature can affect penetrants in a couple of ways. First,
some penetrants can fade at high temperatures due to dye vaporization
or sublimation. Second, high temperatures can cause the penetrant
to dry in the the flaw, preventing it from migrating to the surface
to produce an indication. To prevent harming the penetrant material,
drying temperature should be kept to under 71oC.
The drying should be limited to the minimum length
of time necessary to thoroughly dry the component being inspected.