T.O. 33B-1-1
2-29
2.3.8.2
Removal of Inspection Residues.
2.3.8.2.1
Developer Residue Removal.
Developers are the last material applied in the penetrant process and may be one of several forms. The form of
developer applied (dry powder, nonaqueous, water suspendible or water soluble) greatly influences the method and
difficulties of removal. One point common to most developers is the increase in adherence with time on the part. The
longer a developer remains on a part, the more difficult it is to remove. Removal of the developer coating SHALL be
done as soon as possible after completing the penetrant inspection.
2.3.8.2.1
Removal of Dry Powder Developer.
Dry powder developer adheres to all areas where applied. Some dry powder may lodge in recessed areas, faying surface
joints, or crevices. Dry powder particles can be removed with a water soluble detergent wash followed by a water rinse.
Dry developer particles adhering to penetrant bleed-out will be removed during the removal of residual penetrant
described below in paragraph 2.3.8.2.2
2.3.8.2.1
Removal of Nonaqueous Developer.
NOTE
Spraying aerosol solvent directly on the developer without first hand wiping is not
recommended. This practice spreads the developer particles over a larger area,
which increases the amount of wiping that must be done. Aerosol solvent spraying
may be used as a final step to remove residual or trace amounts of developer when it
is not practical to use water.
Nonaqueous developer is usually applied by spraying from an aerosol can. The majority of applications involve a
relatively small area. This makes it advantageous to remove by initially hand-wiping the surface with a dry cloth or
paper towel to remove most of the developer. The remaining traces of developer can then be removed with a water or
alcohol moistened rag or paper towel. The inspected area may contain threads, crevices, and surface recesses where
wiping will not remove all of the developer particles. These areas should first be wiped to remove as much developer as
possible, and then pressure sprayed with a water and detergent solution. Solvent spraying is not particularly effective,
as the developer is usually insoluble. A vapor degreaser SHALL NOT be used because the elevated temperature bakes
or hardens the developer coating.
2.3.8.2.1
Removal of Water Soluble Developer.
Water soluble developer is the easiest to remove. The developer coating readily re-dissolves in water. Water soluble
developer should be removed by immersion or spraying with water.
2.3.8.2.1
Removal of Water Suspendible Developer.
Water suspendible developer is very similar to non-aqueous developer in removal characteristics. The best method of
removal is immersion and pressure spraying with a hot detergent solution. It can also be removed with a plain water
spray and hand scrubbing with a fiber bristle brush.
2.3.8.2.2
Removal of Penetrant Residues.
Removal of residual penetrant following the inspection and developer removal is almost always required. The amount
of residual penetrant is small, consisting of penetrant retained in discontinuities, crevices, and part surface
irregularities. Penetrant residues generally can be removed with liquid solvents and detergent or alkaline cleaning.
2.3.8.2.3
Protection Of Parts Following Penetrant Inspection.
The penetrant inspection process and subsequent removal of inspection residues leave the parts with a chemically clean
surface. These surfaces, especially ferrous materials, are highly reactive and may corrode from the moisture in air.
Such parts should receive a corrosion protection treatment as soon as practical, following penetrant inspection.
