FED-STD-228A
4.5 At the end of the above cycles of immersion, the specimen shall then be examined for the presence
of blackened areas resulting from the action of sodium polysulfide. Blackening that occurs within 0.5 inch
of the cut ends shall be disregarded. Blackening of the coated surface caused by the treating the
specimen with sodium polysulfide should disappear when treated with hydrochloric acid leaving
blackened areas only where copper is exposed.
4.6 The percentage of the total area of the specimen showing exposed copper (blackened area) shall be
determined by visual examination.
5. RESULTS
5.1 Unless otherwise specified in the detail specification, three specimens from each inspection unit shall
be tested.
5.2 The uniformity of the coating of the conductor of the inspection unit shall be the average of the results
obtained from the specimens tested.
5.3 Two immersed area of the inspection unit showing exposed copper shall be recorded to the nearest 5
percent.
5.4 The number of immersion cycles and temperature of solution shall be recorded.
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