ASTM B201-80(2000)
(Practice)Standard Practice for Testing Chromate Coatings on Zinc and Cadmium Surfaces
Standard Practice for Testing Chromate Coatings on Zinc and Cadmium Surfaces
SCOPE
1.1 This practice covers a procedure for evaluating the protective value of chemical and electrochemical conversion coatings produced by chromate treatments of zinc and cadmium surfaces.
1.2 The protective value of a chromate coating is usually determined by salt-spray test and by determining whether or not the coating possesses adequate abrasion resistance.
1.3 Other methods, such as exposure to a humidity environment, can be used, but are generally of too long a duration to be of practical value. "Steam Tests" using pressure cookers have also been used for testing chromate films on hot-dip galvanized surfaces.
1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety problems associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Endorsed by American
Designation: B 201 – 80 (Reapproved 2000) Electroplaters’ Society
Endorsed by National
Association of Metal Finishers
Standard Practice for
Testing Chromate Coatings on Zinc and Cadmium Surfaces
This standard is issued under the fixed designation B 201; 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 between dissimilar metals should not be considered failure. In
some instances, it may be desirable to regard the first appear-
1.1 This practice covers a procedure for evaluating the
ance of red rust as failure.
protective value of chemical and electrochemical conversion
3.1.2 significant surfaces—in general, significant surfaces
coatings produced by chromate treatments of zinc and cad-
are those surfaces that are visible and subject to corrosion or
mium surfaces.
wear, or both, except that surfaces that are normally difficult to
1.2 The protective value of a chromate coating is usually
coat by electroplating or mechanical deposition may be ex-
determined by salt-spray test and by determining whether or
empt. The designation of significant surfaces may be indicated
not the coating possesses adequate abrasion resistance.
on the drawing.
1.3 Other methods, such as exposure to a humidity environ-
ment, can be used, but are generally of too long a duration to
4. Significance and Use
be of practical value. “Steam Tests” using pressure cookers
4.1 This practice is applicable to chromate coatings of the
have also been used for testing chromate films on hot-dip
colorless (both one and two-dip), iridescent yellow or bronze,
galvanized surfaces.
olive drab, black, colorless anodic, yellow or black anodic
1.4 This standard does not purport to address all of the
types, and of the dyed variety, when applied to surfaces of
safety concerns, if any, associated with its use. It is the
electrodeposited zinc, mechanically deposited zinc, hot-dipped
responsibility of the user of this standard to establish appro-
zinc, rolled zinc, electrodeposited cadmium, mechanically
priate safety and health practices and determine the applica-
deposited cadmium, and zinc die castings.
bility of regulatory limitations prior to use.
NOTE 1—Colorless coatings are also referred to as clear-bright or
2. Referenced Documents
blue-bright coatings.
2.1 ASTM Standards:
4.2 Because of variables inherent in the salt-spray test,
B 117 Practice for Operating Salt Spray (Fog) Apparatus
which may differ from one test cabinet to another, interpreta-
tion of test results for compliance with expected performance
3. Terminology
should be specified by the purchaser.
3.1 Descriptions of Terms:
4.3 Properties such as thickness, color, luster, and ability to
3.1.1 time to failure—time to failure will depend on the type
provide good paint adhesion are not covered in this practice,
of coating tested. A list of some expected protective values
nor are the chemical composition and the method of applica-
obtainable in a given salt spray test is shown in Appendix X2.
tion of these finishes.
3.1.1.1 Discussion—In most instances, failure is defined as
the first appearance on significant surfaces of white corrosion
5. Conditioning
products visible to the unaided eye at normal reading distance,
5.1 Aging—Before subjecting a chromate coating to test, it
except that the presence of white corrosion products at sharp
must be aged at room temperature in a clean environment for
edges (for example, on threaded fasteners) and at junctions
at least 24 h after the chromating treatment.
5.2 Preparation of Specimen—The test surface must be free
of fingerprints and other extraneous stains and must not be
This practice is under the jurisdiction of ASTM Committee B-8 on Metallic and
cleaned except by gentle wiping with a clean, dry, soft cloth to
Inorganic Coatingsand is the direct responsibility of Subcommittee B08.07 on
Chemical Conversion Coatings.
remove loose particles. Oily or greasy surfaces should not be
Current edition approved Aug. 1, 1980. Published January 1981. Originally
used for testing, and degreasing with organic solvents is not
published as B 201 – 45 T. Last previous edition B 201 – 68.
2 recommended.
Annual Book of ASTM Standards , Vol 03.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
B 201 – 80 (2000)
6. Procedure 6.3.1 Determine the presence of a colorless (clear) coating
by placing a drop of lead acetate testing solution on the surface.
6.1 Salt Spray Test—Expose the clean specimen to a 5 %
Allow the drop to remain on the surface for 5 s. Remove the
solution salt spray and conduct the test in accordance with the
testing solution by blotting gently, taking care not to disturb
latest revision of Practice B 117. Unless otherwise specified,
any deposit that may have formed. A dark deposit or black stain
only those surfaces that are positioned in the test chamber in
is indicative of the absence of a coating.
accordance with Practice B 117 are considered pertinent for
6.3.2 Prepare the test solution by dissolving 50 g of lead
evaluating failure.
acetate trihydrate (Pb(C H O ) ·3H O) in 1 L of distilled or
6.2 Abrasion Resista
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