MIL-HDBK-1110
differences in calibration procedures between SSPC PA 2 and the
ASTM standards. If the contract specification does not specify
the exact procedures to be used, the procedures should be agreed
upon, and the agreement documented, during the preconstruction
conference.) ASTM D 4128, Identification of Organic Compounds in
Water by Combined Gas Chromatography and Electron Impact Mass
Spectrometry describes a destructive procedure for measuring
coating thickness on non-metallic substrates using a Tooke gage
(refer to Section 10). If the contract specification requires
minimum film thicknesses for each layer, the measurements must be
made after each layer has cured, taking care not to depress soft
coatings during measurements.
9.6.8.5
Drying. The inspector should ensure that a previous
coat has dried or cured as required by the contract specification
before another coat is applied. For most thermosetting coatings,
manufacturers specify a maximum, as well as a minimum, curing
time before application of the next coat. In some situations, a
coating manufacturer may require use of a methyl ethyl ketone
(MEK) rub test to assess curing prior to application of another
layer. The inspector's record should provide information so that
the dry/cure time for each layer can be determined.
9.6.9
Final Approval Procedures. The final approval
inspection is very important since it determines whether the
contract requirements have been met, and whether identified
deficiencies have been corrected. Since most coatings function
as a barrier and since the protection of a surface is usually
directly related to coating thickness and continuity, inspection
of coating thickness and film continuity are essential. The
following checklist can be used to inspect the final job:
a) Examine, as required by the specification, the
cured coating system for visual defects, such as runs, sags,
blistering, orange peel, spray contaminants, mechanical damage,
color and gloss uniformity, and incomplete coverage. Note any
areas of rusting, or other evidence of premature failure of the
coating system.
b) If defects are observed, bring them to the
attention of the contractor for correction. If resolution of the
corrective action cannot be reached with the contractor, bring
the matter to the attention of the contracting officer. Dated
photographs of the defects could become part of the inspector's
records, if deemed appropriate.
c) Measure and record the total dry film thickness
using appropriate gages. When the Tooke gage is used, the
coating must later be repaired.
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