T.O. 33B-1-1
1-35
(9)
Using tweezers, insert a quartered piece of filter paper into the cylinder mixture, withdraw the
paper and set it aside to air dry.
(10)
When both filter papers (reference and in-use) are dry, compare the fluorescent brightness of the
filter papers to each other under a blacklight. If a significant difference of fluorescent brightness
is noted, the fluorescent properties of the in-use production line penetrant have deteriorated, and
the fluorescent sensitivity will probably not be acceptable. Follow accepted activity standards to
process and perform additional testing or to discard the contaminated/degraded material.
(11)
At the conclusion of the fluorescent brightness testing, clean the cylinder with acetone
(Specification 0-A-51F), rinse with water, and again clean with acetone. Dry with clean filtered
compressed air.
c. Rapid Brightness Test (Field). A rough check of penetrant baths can be accomplished by comparing
their appearance on an absorbent material, preferably the filter paper used in paragraph 1.5.5.2.2b
above. Place a drop of the working bath penetrant on a paper towel. Place a second drop of penetrant
from the reference standard near the drop from the working bath. When the two drops merge, examine
under a black light for difference in color and brightness.
1.5.5.3
Testing Lipophilic Emulsifier.
Penetrant is an unavoidable contaminant of lipophilic emulsifier. It is carried into the emulsifier on the surface of parts
where it dissolves and is washed off during immersion and drain. Since emulsifier and penetrant are miscible in all
concentrations, even small quantities of fluorescent dye will cause the emulsifier to fluoresce. The fluorescent
brightness increases with increasing dye content, but it is impossible to visually estimate penetrant contamination by
observation of the tank surface.
1.5.5.3.1
Emulsifier will continue to function when contaminated with penetrant; however, when the penetrant concentration
reaches a certain level, the emulsification action slows and eventually stops. The military procurement specification
requires a 4 to 1 mixture of emulsifier to penetrant to leave no more residual background than the uncontaminated
emulsifier.
1.5.5.3.2
Removability Test.
NOTE
Grit blasting using 100 mesh aluminum oxide grit is required only on locally
manufactured panels to roughen the surface and is only required one time.
Normally ultrasonic cleaning or solvent cleaning is performed after grit blasting.
a. In-use lipophilic emulsifiers SHALL be periodically tested for contamination. A two-inch by four inch,
16 gauge (0.060") annealed type 301 or 302 stainless steel panel is required. The panel SHALL be
ultrasonically cleaned or vapor degreased and grit blasted on both sides using 100 mesh, aluminum
oxide grit (not beads), using 60 psig air pressure, with the gun held normal to and approximately 18
inches from the panel surface. After blasting, the panel surface should be handled by the edges only
and protected from contamination by wrapping in tissue paper.
b. Immerse the panel in the working penetrant bath and allow it to drain for 10 minutes at approximately
a 60° (±15) angle. At the end of the drain period apply working bath emulsifier to one half of the
panel and reference standard emulsifier to the other half. Application may be either by pouring or
immersion. If pouring is used, place a small quantity of both working bath emulsifier and reference
standard emulsifier into separate containers that are suitable for pouring. Apply the emulsifier to the
upper edge of the panel so it flows down across half of the panel face. This shall be done with the panel
in an upright position. It is desirable to have the two emulsifier strips close together at the center of the
