ASTM B137-95(2000)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Endorsed by American
Designation: B 137 – 95 (Reapproved 2000) Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Test Method for
Measurement of Coating Mass Per Unit Area on Anodically
Coated Aluminum
This standard is issued under the fixed designation B 137; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope 5. Test Specimen
1.1 This test method covers determination of the mass per 5.1 Prepare a test specimen of known surface area, prefer-
unit area of coating on anodically coated aluminum and its ably a piece about 75 mm square. If the anodic coating is
alloys. contaminated or impregnated with oil, grease, lacquer, etc.,
1.2 This standard does not purport to address all of the remove as much as possible of this material before determining
safety concerns, if any, associated with its use. It is the the mass of the coating. It is not usually practicable to remove
responsibility of the user of this standard to establish appro- these materials from the pores of the coating, but surface films
priate safety and health practices and determine the applica- can frequently be removed by wiping the sample with a cloth
bility of regulatory limitations prior to use. wet with a suitable solvent.
5.2 In cases where it is required to measure the mass of
2. Referenced Documents
coating on only one side of a specimen where both sides have
2.1 ASTM Standards: anodic coatings, the following procedure may be used:
D 1193 Specification for Reagent Water
5.2.1 Prepare a specimen somewhat larger than required for
5.1.
3. Significance and Use
5.2.2 Apply a suitable stop off around the edges of the
3.1 This test method is a destructive test procedure suitable
specimen so that the area on the side of the specimen that is not
for quality control within manufacturing operations for coating
to be tested is about 75 mm square. Paraffin wax has been used
mass on anodically coated aluminum and aluminum alloys.
for this purpose, but any stop off that resists warm sodium
The mass of the coating is an approximation of its thickness
hydroxide is suitable.
provided the conditions under which the coating was applied,
5.2.3 Swab the area with a warm solution of sodium
or the density of the coating, are known. An anodic coating’s
hydroxide (10 mass %, 100 g/L) until bare metal is exposed,
protective value and amenability to coloring by dying or
which is indicated by uniform bubbling over the entire exposed
electrolytic methods are related to mass of coating per unit
surface.
area.
5.2.4 Swab with warm distilled water.
5.2.5 Dry with a clean cloth.
4. Reagents
5.2.6 Swab with diluted nitric acid (1 part HNO , density
4.1 The test solution shall have the following makeup:
1.41, plus 1 part water).
Chromic acid anhydride (CrO)20 6 0.5 g
5.2.7 Rinse with warm deionized or distilled water.
Orthophosphoric acid of 85 mass %, density
5.2.8 Dry at approximately 100°C until dry.
1.69 35 6 0.5 mL
5.2.9 Cool and shear off the area covered with stop off, so
Distilled or deionized water conforming with
Type III Reagent Water of Specification
that the coated area
...