FED-STD-228A
4.1.2 Reference color standard; copper sulfate-ammonium hydroxide. The reference color standard
solution shall be prepared by dissolving 0.100 grams of anhydrous copper sulfate in distilled water,
adding 75 milliliters of c.p. ammonium hydroxide, specific gravity 0.90, and diluting the volume to 1 liter
with distilled water.
4.2 Unless otherwise specified in the detail specification, the specimen shall be immersed for a period of
15 ± ½ minute at a temperature of 30° ± 1°C (86° ± 2°F).
4.3 The specimen shall be free from mechanical damage. The specimen shall be cleaned by immersing
in suitable solvent for not less than 3 minutes and wiping dry with clean cheesecloth. The cleaned
specimen shall not be handled with bare hands or come in contact with foreign matter and shall be kept
wrapped in a clean cloth until required for test. The ends of the specimen shall be coated with melted
paraffin to protect the exposed copper. The paraffin-coated length shall not be included in determining
the length of the specimen.
4.4 The specimen of the required length, 2.1, shall be immersed in a test tube in the quantity of test
solution specified in table II for the required period of time at the required temperature.
TABLE II
Quantity of
Wire diameter (inch)
test solution
(milliliters)
0.460 0.321 - - - - - -
150
0.320 0.161 - - - - - -
100
0.160 0.0810 - - - - -
50
0.0800 0.0400 - - - -
25
0.0390 0.0030 - - - -
12.5
4.5 The specimen shall then be removed and the color of the test solution compared with that of an equal
volume of color standard in a test tube of equal dimensions. The discontinuity of the coating is
represented by the intensity of the color of the test solution in relation to the intensity of color of the
standard solution. The color comparison shall be made by viewing the solutions lengthwise against a
white back ground. If available, a colorimeter or spectrophotometer may be used in making the color
comparison.
4.6 The intensity of the color of the test solution relative to the reference color standard for each
specimen shall be recorded.
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 results obtained from
the specimens tested.
5.3 The time and temperature of immersion shall be recorded.
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