ASTM B537-70(2012)e1

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: B537 − 70(Reapproved 2012)
Standard Practice for
Rating of Electroplated Panels Subjected to
Atmospheric Exposure
This standard is issued under the fixed designation B537; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
ε NOTE—Units statement was added to the Scope editorially in May 2012.
1. Scope B380Test Method for Corrosion Testing of Decorative
Electrodeposited Coatings by the Corrodkote Procedure
1.1 This practice covers a preferred method for evaluating
the condition of electroplated test panels that have been 2.2 ASTM Adjunct:
exposedtocorrosiveenvironmentsfortestpurposes.Itisbased Dot charts (9 charts, 8 ⁄2 by 11 in.) (9 color photos, 3 by 5
onexperienceinuseofthemethodwithstandard10-by15-cm in.)
panelsexposedonstandardASTMracksatoutdoortestsitesin
natural atmospheres. It has been used also for rating similar 3. Basis of Procedure
panels that have been subjected to accelerated tests such as
3.1 The rating method described in this recommended
those covered by Practice B117, Method B287, Test Method
practice is based on the recognition that typical decorative-
B368, and Test Method B380. Any modifications needed to
protective deposits such as nickel/chromium, with or without a
adapt the method to rating actual production parts are not
copper undercoat, have two functions: ( 1) to protect the
considered in this practice.
substrate from corrosion and thus prevent degradation of
1.2 This practice refers only to decorative-protective coat- appearance caused by basis metal corrosion products (for
ings that are cathodic to the substrate, typified by nickel/ example, rust and rust stain); and (2) to itself maintain a
chromium or copper/nickel/chromium on steel or zinc die satisfactoryappearance.Althoughthesefunctionsoverlap,they
castings. It is not intended for use with anodic sacrificial can be evaluated separately and it is frequently desirable to do
coatings such as zinc and cadmium on steel. so. Accordingly, this practice assigns separate ratings to (1)
appearance as affected by corrosion of the substrate and (2)
1.3 The values stated in SI units are to be regarded as
appearance as affected by deterioration of the coating itself.
standard. No other units of measurement are included in this
standard. 3.2 The rating number assigned to the ability of the coating
to protect the substrate from corrosion is called the “protec-
2. Referenced Documents tion” number or rating.
2.1 ASTM Standards: 3.3 The rating number assigned to the inspector’s judgment
B117Practice for Operating Salt Spray (Fog) Apparatus of the overall appearance of the panel, including all defects
B287Method of Acetic Acid-Salt Spray (Fog) Testing caused by the exposure (Note 1), is called the “appearance”
(Withdrawn 1987) number or rating.
B368Test Method for Copper-AcceleratedAceticAcid-Salt
NOTE 1—Panels that are not “perfect” even before being exposed
Spray (Fog) Testing (CASS Test)
should normally be rejected (see Note 4).
3.4 The result of inspecting a panel is recorded as two
numbers separated by a slash (/), the protection number being
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
given first.
and Inorganic Coatingsand is the direct responsibility of Subcommittee B08.05 on
Decorative Coatings.
3.5 In addition to recording the numerical rating of a panel,
Current edition approved May 1, 2012. November 2013. Originally approved in
the inspector should note the type(s) and severity of defect(s)
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1970. Last previous edition approved in 2007 as B537–70 (2007) . DOI:
contributing to the rating. This may be done by the use of
10.1520/B0537-70R12E01.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. Color reproductions of these photographs are available from ASTM Interna-
The last approved version of this historical standard is referenced on tional Headquarters. Order Adjunct No. ADJB0537. Original adjunct produced in
www.astm.org. 1987.
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B537 − 70 (2012)
agreed symbols for the most common defects (Appendix X1) area absolutely necessary for the purpose, preferably not more
and abbreviations for degree or severity of these defects. than 1 cm of a 10- by 15-cm panel.
4. Types of Defects 6. Assignment of Protection Rating
6.1 The numerical rating system is based on the area
4.1 “Protection” defects include crater rusting (Note 2),
pinhole rusting, rust stain, blisters (Note 3), and any other covered by protection defects, by the following equation:
defects that involve basis metal corrosion.
R 5 3 ~2 2 logA! (1)
NOTE 2—“Rusting” or “rust” as used in this document includes
where R=rating and A=percentage of the total area cov-
corrosion products of the substrate and is not confined to iron or steel: the
ered by defects. R is rounded off to the nearest whole number,
white corrosion products of zinc die castings and aluminum, for example,
leading to the tabulation given in Table 1.
are included in this term.
NOTE3—Blistersonplatedzincdiecastingusuallyconnotebasismetal 6.1.1 Strict application of the equation given in 6.1 would
corrosion;buttheinspector’sjudgmentmayberequiredtodecidewhether
lead to ratings greater than 10 for panels with extremely small
a blister does or does not arise at the substrate-coating interface.
defective areas. Rating 10, accordingly, is arbitrarily assigned
4.2 “Appearance” defects include, the addition to those
to a panel with no defects, and the equation operates at ratings
caused by basis metal corrosion, all defects that detract from
9 and below.
the appearance (that is, the commercial acceptability) of the
6.1.2 If desired, fractional ratings between 9 and 10 may be
panel. Typical are: surface pits, “crow’s feet,” crack patterns,
assigned to panels judged better than 9 but not perfect.
surface stain, and tarnish.
Fractional ratings below 9, although normally not especially
useful, may be assigned if desired.
4.3 Defects developing on exposure that reflect improper
preparationorplatingshouldbenotedbutnoattemptshouldbe
6.2 As an aid in judging the defective area, standards of
made to rate panels showing major amounts of such defects.
comparison, consisting of photographs of panels or of dot
Peeling of the coating from the substrate, or of one coat from
charts are made part of this practice. See Appendix X2. These
another, is the principal such defect.
photographs and charts are 10 by 15 cm to facilitate compari-
son with the panel being inspected. The standards represent as
5. Preparation for and Manner of Inspection
nearly as possible the maximum amount of corrosion permis-
NOTE4—Itmaybedesirabletoexposepanelsfortesteventhoughthey
sible for a given rating; there is a standard for each rating 1
are defective in certain respects before exposure. In that case, an
through 9.Apanel worse than the standard for rating 1 would
inspection should be made and recorded before the panels are exposed.
rate 0.
5.1 Panels may be inspected on the exposure racks or may
6.2.1 The types of corrosion defects normally encountered
be removed to a more suitable location if necessary. Lighting
differ according to the type of atmospheric exposure. Typical
during inspection should be as nearly uniform as possible;
decorative deposits exposed to marine atmospheres often tend
direct reflection from sun or clouds should be avoided, and
tofailbycraterrusting,whereasinindustrialatmospheres,they
various angles of inspection should be tried to ensure that
are more likely to exhibit pinpoint rusting; and the latter
defects show up.
atmosphere also tends to be more severe with regard to
5.2 If the condition of the panels allows, inspection should
degradation of the coating system but somewhat less severe
be made in the “as-is” condition. If dirt, salt deposits, and so with regard to basis metal corrosion. For this reason, the same
forth, make it impractical to inspect them, panels may be
standard comparison photographs or charts are not suitable for
spongedwithamildsoapsolutionfollowedbywaterrinse;but use at both types of locations; photographs are more helpful in
no pressure should be exerted in this procedure such as would
assessing panels exposed to marine atmospheres, whereas dot
tend to upgrade the rating by, for example, cleaning off rust or
charts can be used for industrial locations (Appendix X2).
rust stain. Panels should be allowed to dry before inspecting
6.3 In rating any given panel, it is recommended that the
them.
appropriateseriesofstandardsbeplacedbesideitandthebasis
5.3 Defects to be noted and taken into account in rating
metal corrosion defects in the panel be matched as nearly as
panelsincludeonlythosethatcanbeseenwiththeunaidedeye
possible with one of the standards. If the panel is somewhat
(Note 5) at normal reading distance.
NOTE 5—“Unaided eye” includes wearing of correctional glasses if the
TABLE 1 Protection Rating Versus Area of Defect
inspector normally wears them.
Area of Defect (in percent) Rating
5.3.1 Optical aids may be used to identify or study defects
once they are found by unaided eye inspection.
To 0.1 9
0.1to0.25 8
5.4 Edgedefects,occurringwithin6.5mmoftheedgesofa
0.25 to
...