MIL-DTL-5541F
type I materials, existence of a coating can be verified by using a simple spot test specified in
ASTM-B449. For type II materials, existence of a coating should be verified per the
manufacturer's recommendation
6.9 Determination of a corrosion spot or pit. As a general rule, a corrosion spot or pit
usually displays a characteristic tail or line, however, any visible corrosion or pitting except
scratches or substrate surface defects is to be counted..
6.10 Test specimens (2024-T3). Due to high copper content, 2024-T3 aluminum alloy test
specimens are more susceptible to salt spray failure than 6061-T6 aluminum alloy test specimens
(see 4.2.2).
6.11 Chemical analysis of the conversion solution. Note that many conversion materials do
not react sufficiently with aluminum surfaces at low temperatures. Conversion coating of parts
in an unheated facility, such as a hangar, during colder periods of the year is not recommended.
6.12 Paint adhesion. Coated parts should be allowed to dry in accordance with the
chemical manufacturer's recommendation before they are subsequently painted or adhesion
failures may occur. When coated parts are stored for extensive periods before painting, they
should be cleaned in accordance with 3.2 to reactivate the surface by removing dust particles.
Excessively thick coatings may result in paint adhesion problems, such as blistering, due to
higher amounts of soluble material under the paint.
6.13 Paint compatibility. Compatibility problems between conversion coatings and certain
Chemical Agent Resistant Coatings (CARC) have been reported.
6.14 Temperature effects on corrosion protection. Unpainted conversion coatings will
commence losing corrosion resistance properties if exposed to temperatures of 140 ºF (60 ºC) or
higher, during drying, subsequent fabrication, or service. As temperatures and exposure times
increase, the corrosion protection of unpainted conversion coated parts decreases. The reduction
is believed to result from the coating dehydrating and the resulting insolubility of the chromates
within the coating.
6.15 Solution analysis documentation. Documentation of the history of each processing
bath, showing additions of replenishing chemicals to the bath and the results of all solution
analyses performed must be maintained. Testing of the solution should be consistent with best
industry practices and manufacturer's recommendations. Upon request of the acquisition
activity, such records, as well as reports of the test results, should be made available. These
records must be maintained for not less than one year after completion of the contract or order.
6.16 Shelf life. This specification covers items where shelf life is a consideration. Specific
shelf-life requirements should be specified in the contract or purchase order. The shelf-life
codes are contained in the Federal Logistics Information System Total Item Record. Additive
information for shelf-life management may be obtained from DoD 4140.27-M, Shelf-life
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