T.O. 33B-1-1
1-33
Prepare the reference developer sample by mixing a small batch of previously reserved developer solids
in the same ratio as the solution in your tank. For example, if the solution in your tank was prepared at
1/2 lb. per gallon of water then mix the reference sample at 1/2 lb. per gallon of water. This one gallon
reference sample can be used until depleted, but must be discarded when the solution in the tanks is
changed, along with the remainder of your dry reference solids. The test panels should be processed
side by side, and with one end slightly raised, rather than flat, on the worktable. Use the working
materials on one panel and the reference materials on the other. Apply penetrant by brushing,
swabbing, or flowing. Brushing or swabbing is preferred since it permits better control over the
quantity of penetrant applied.
c. Penetrant dwell time of 2 or 3 minutes is usually adequate since the shallow cracks are rapidly
penetrated. Apply lipophilic emulsifier by carefully flowing or pouring each material in turn on its
respective panel. Hydrophilic materials are applied by immersing the panels. Emulsification or
removal time is also very short, typically around 10 to 20 seconds. This will vary with different
penetrant emulsifier or remover combinations. Initially, several trials should be made to determine the
proper emulsification or removal time. The shortest possible time to remove the surface penetrant with
the reference materials shall be used. Water washable penetrants should be washed as gently as
possible under a black light. Wash time should be limited to removal of surface penetrant only.
Solvent removal should be done by hand wiping with a separate dry cloth or towel on each panel.
Removal of any residual penetrant should be done with the cloth or towel just lightly moistened with
solvent. DO NOT saturate the cloth or towel. Care must be exercised to prevent mixing of test and
reference materials during removal. DO NOT use the same cloth or towel on both panels.
d. Developer may be applied by immersion, flowing, or spraying. Ensure developers have been mixed
properly (see paragraph 1.5.4.2b). Water suspended developers must be thoroughly agitated just before
applying them to the panels. If water soluble developers are used, agitation is not required. Because of
the shallow crack depths on the panels, volatile components of the penetrants will quickly evaporate and
care must be taken when drying the panels. Minimum drying time SHALL be used to ensure the panels
do not become too hot to handle with bare hands. Developer dwell time is 2 to 3 minutes after the
panels are completely free of moisture.
e. Examine the panels side by side, under a black light, first noting the overall brightness and color of the
indications. Then examine in detail by following individual indications across both panels. Note the
presence, absence or diminishing of crack indications on the working solution panels and observe the
continuity, size and color.
(1)
Any distinct difference is cause for additional testing to determine if the penetrant,
emulsifier/remover, or the developer caused the difference in the indications. Perform additional
tests as described in paragraph 1.5.5.
(2)
When no distinct difference is noted, system performance testing is complete.
f. The panel SHALL be cleaned as soon as possible after completing the process check. The cleaning
procedures SHALL be used.
1.5.4.3
Storage of Panels.
The panels must be stored in a clean environment to retard degradation. The panels can be stored in a dry air
environment or placed in mineral spirits or alcohol. If the panels are stored in mineral spirits, degreasing will be
required prior to use. The panels do not have an indefinite life as penetrant and developer residues plus oxides retained
in the cracks, will gradually clog or fill the cracks, thus reducing the apparent size of the indication.
