Instructions:
Penetrant inspection is
used on nonporous metal and nonmetal components to find material
discontinuities that are open to the surface and may not be
evident to normal visual inspection. The part must be clean
before performing a penetrant inspection. The basic purpose of
penetrant inspection is to increase the visible contrast between
a discontinuity and its background. This is accomplished by
applying a liquid of high penetrating power that enters the
surface opening of a discontinuity. Excess penetrant is removed
and a developer material is then applied that draws the liquid
from the suspected defect to reveal the discontinuity. The
visual evidence of the suspected defect can then be seen either
by a color contrast in normal visible white light. (See below.)