FED-STD-791D
6. PROCEDURES
6.1 Prepare the copper strip as follows:
6.1.1 Using progressively finer grades of abrasive paper, remove all surface
blemishes from one side of strip.
6.1.2 Polish strips with the 240-grit paper to remove any marks produced by the
coarser abrasive. Do not touch the strips with the fingers. Handle strips only with
lint-free paper or tongs. Store strips immersed in acetone until ready for final polishing.
6.1.3 Remove strips from the acetone, and final polish one side to a mirror
finish, using 150-mesh silicon carbide grit (held on an acetone-moistened cotton pad).
6.1.4 Clean all metal dust from the strip by rubbing vigorously with clean pads
of absorbent cotton until a fresh pad remains unsoiled.
6.1.5 Wash strips in fresh warm n-hexane, then in fresh warm acetone, and allow
to air dry.
NOTE 1:
Caution. n-Hexane and acetone are toxic. Use only in a well ventilated
area. Do not breathe its fumes nor allow it to come in contact with the
skin. Keep all flames away from these materials.
6.2 Place approximately one-half of the sample on each strip, taking care to
leave approximately half of the polished surface exposed.
6.3 Cover the strips with inverted watch glasses, and let stand at room
temperature for 24 h.
6.4 Remove the watch glasses, and visually examine the sample for a green color.
6.5 Wash the copper strips in non-corrosive n-hexane and inspect them for brown
stains.
7. CALCULATION
7.1 This section is not applicable to the test procedure.
8. REPORT
8.1 Report the lack or the presence of any evidence of corrosion (green color in
sample or stain on copper sheets).
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