ASTM B537-22

Standard Practice for Rating of Electroplated Panels Subjected to<brk/> Atmospheric Exposure

ABSTRACT
This practice covers the recommended method for rating the condition of electroplated test panels subjected to corrosive environments for test purposes. This method is used with standard-sized panels exposed on standard ASTM racks at outdoor test sites in both natural atmospheres and accelerated test conditions. This practice refers only to decorative-protective coatings that are cathodic to the substrate such as nickel/chromium or copper/nickel/chromium on steel or zinc die castings, and is not intended for use with anodic sacrificial coatings such as zinc and cadmium on steel. Any modifications needed to adapt the method to rating actual production parts are not considered here. Panels shall be assigned separate rating numbers based on the ability of the coating to protect the substrate from corrosion (protection rating), and the overall appearance of panels as affected by deterioration of the coating itself (appearance rating). Accordingly, rating numbers shall be derived from the type of defect that exists, that is: (1) protection defects, which include crater rusting, pinhole rusting, rust stains, blisters, and other defects that involve basis metal corrosion; and (2) appearance defects, which include surface pits, "crow's feet," crack patterns, surface stains, tarnishes, and other defects that detract from commercial acceptability as to appearance. Inspection should be made in the as-is condition, and defects to be taken into account are only those that can be seen with the unaided eye at normal reading distance.
SCOPE
1.1 This practice covers a preferred method for evaluating the condition of electroplated test panels that have been exposed to corrosive environments for test purposes. It is based on experience in use of the method with standard 10- by 15-cm (4- by 6-in.) panels exposed on standard ASTM racks at outdoor test sites in natural atmospheres. It has been used also for rating similar panels that have been subjected to accelerated tests such as those covered by Practice B117, Method B287, Test Method B368, and Test Method B380. Any modifications needed to adapt the method to rating actual production parts are not considered in this practice.  
1.2 This practice refers only to decorative-protective coatings that are cathodic to the substrate, typified by nickel/chromium or copper/nickel/chromium on steel or zinc die castings. It is not intended for use with anodic sacrificial coatings such as zinc and cadmium on steel.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Sep-2022
• ICS: 25.220.40 - Metallic coatings
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.05 - Decorative Coatings

Relations

• Refers: ASTM B380-97(2013) - Standard Test Method for Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure
• Effective Date: 01-Dec-2013
• Refers: ASTM B117-11 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Oct-2011
• Refers: ASTM B117-09 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Jul-2009
• Refers: ASTM B368-09 - Standard Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)
• Effective Date: 15-Apr-2009
• Refers: ASTM B380-97(2008)e1 - Standard Test Method for Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure
• Effective Date: 01-Apr-2008
• Refers: ASTM B117-07a - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 15-Dec-2007
• Refers: ASTM B380-97(2007) - Standard Test Method of Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure
• Effective Date: 01-Oct-2007
• Refers: ASTM B117-07 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Mar-2007
• Refers: ASTM B117-03 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Oct-2003
• Refers: ASTM B368-97(2003)e1 - Standard Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)
• Effective Date: 10-May-2003
• Refers: ASTM B117-02 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 10-Oct-2002
• Refers: ASTM B380-97 - Standard Test Method of Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure
• Effective Date: 10-Oct-1997
• Refers: ASTM B380-97(2002) - Standard Test Method of Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure
• Effective Date: 10-Oct-1997
• Refers: ASTM B117-97 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 10-Apr-1997
• Refers: ASTM B368-97 - Standard Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)
• Effective Date: 01-Jan-1997

Overview

ASTM B537-22: Standard Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure provides comprehensive guidelines for evaluating the condition of electroplated test panels exposed to corrosive environments. Developed by ASTM International, this standard offers a uniform method for rating the protection and appearance of decorative-protective coatings, especially those that are cathodic to the substrate such as nickel/chromium or copper/nickel/chromium on steel or zinc die castings. ASTM B537-22 is crucial for ensuring reliable assessment of corrosion resistance and decorative finish in controlled outdoor or accelerated test environments, supporting the quality and durability of electroplated surfaces.

Key Topics

• Scope of Evaluation: Applies to standard-sized electroplated panels exposed at outdoor test sites or subjected to accelerated laboratory corrosion tests. It is specifically designed for cathodic decorative-protective coatings.
• Protection and Appearance Ratings:
  • Protection Rating: Focuses on the ability of the coating to prevent substrate corrosion (e.g., crater rusting, pinhole rusting, rust stains, blisters).
  • Appearance Rating: Evaluates the visual condition of the coating itself, considering defects like surface pits, craquelure, stains, and tarnish.
• Defect Assessment: Defects are visually inspected without optical aids at normal reading distance, with severity and extent categorized using standardized abbreviations and rating symbols.
• Rating Scale: Numerical values are assigned to panels based on the percent area affected by defects, facilitating quantitative comparison and tracking of corrosion resistance.
• Limitations: The standard does not cover modifications necessary for actual production parts or anodic (sacrificial) coatings, such as zinc or cadmium on steel.
• Testing Methodology: Guidance is provided for panel inspection conditions, cleaning procedures before inspection, and ensuring unbiased assessment using dot charts and photographic standards.

Applications

• Corrosion Testing Laboratories: Ensures consistency in evaluating the atmospheric corrosion resistance of decorative electroplated panels, supporting research and product development.
• Quality Control in Plating Facilities: Provides a reliable method for periodic testing and verification of coating performance prior to product release.
• Automotive and Appliance Manufacturing: Critical for assessing the durability and longevity of decorative finishes on exposed parts, aiding in material selection and process validation.
• Material Certification and Regulatory Compliance: Supports reporting, documentation, and certification requirements for suppliers and end-users of electroplated components.
• Supplier and Client Communication: Establishes a common reference and language for rating and discussing surface defects observed during exposure testing.

Related Standards

• ASTM B117: Practice for Operating Salt Spray (Fog) Apparatus, often referenced for accelerated corrosion testing of coatings.
• ASTM B368: Test Method for Copper-Accelerated Acetic Acid-Salt Spray (CASS) Testing, a key accelerated test for evaluating decorative coatings.
• ASTM B380: Test Method for Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure.
• ASTM B287 (Withdrawn): Acetic Acid-Salt Spray (Fog) Testing.

Keywords: atmospheric exposure, electroplated panels, corrosion rating, decorative coatings, ASTM B537-22, protection rating, appearance rating, cathodic coatings, panel evaluation, accelerated corrosion testing.

By following ASTM B537-22, organizations can maintain high standards in the assessment of decorative electroplated coatings, ensuring product reliability, long-term performance, and customer satisfaction in corrosion-prone environments.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: B537 − 22
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.
1. Scope B287Method of Acetic Acid-Salt Spray (Fog) Testing
(Withdrawn 1987)
1.1 This practice covers a preferred method for evaluating
B368Test Method for Copper-AcceleratedAceticAcid-Salt
the condition of electroplated test panels that have been
Spray (Fog) Testing (CASS Test)
exposedtocorrosiveenvironmentsfortestpurposes.Itisbased
B380Test Method for Corrosion Testing of Decorative
onexperienceinuseofthemethodwithstandard10-by15-cm
Electrodeposited Coatings by the Corrodkote Procedure
(4- by 6-in.) panels exposed on standard ASTM racks at
outdoor test sites in natural atmospheres. It has been used also
3. Basis of Procedure
forratingsimilarpanelsthathavebeensubjectedtoaccelerated
tests such as those covered by Practice B117, Method B287, 3.1 The rating method described in this recommended
Test Method B368, and Test Method B380.Any modifications practice is based on the recognition that typical decorative-
neededtoadaptthemethodtoratingactualproductionpartsare protective deposits such as nickel/chromium, with or without a
not considered in this practice. copper undercoat, have two functions: (1) to protect the
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)
1.3 This standard does not purport to address all of the
appearance as affected by corrosion of the substrate and (2)
safety concerns, if any, associated with its use. It is the
appearance as affected by deterioration of the coating itself.
responsibility of the user of this standard to establish appro-
3.2 The rating number assigned to the ability of the coating
priate safety, health, and environmental practices and deter-
to protect the substrate from corrosion is called the “protec-
mine the applicability of regulatory limitations prior to use.
tion” number or rating.
1.4 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3.3 The rating number assigned to the inspector’s judgment
ization established in the Decision on Principles for the
of the overall appearance of the panel, including all defects
Development of International Standards, Guides and Recom-
caused by the exposure (Note 1), is called the “appearance”
mendations issued by the World Trade Organization Technical
number or rating.
Barriers to Trade (TBT) Committee.
NOTE 1—Panels that are not “perfect” even before being exposed
should normally be rejected (see Note 4).
2. Referenced Documents
3.4 The result of inspecting a panel is recorded as two
2.1 ASTM Standards:
numbers separated by a slash (/), the protection number being
B117Practice for Operating Salt Spray (Fog) Apparatus
given first.
3.5 In addition to recording the numerical rating of a panel,
This practice is under the jurisdiction of ASTM Committee B08 on Metallic
the inspector should note the type(s) and severity of defect(s)
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.05 on
contributing to the rating. This may be done by the use of
Decorative Coatings.
agreed symbols for the most common defects (Appendix X1)
Current edition approved Oct. 1, 2022. Published November 2022. Originally
and abbreviations for degree or severity of these defects.
approvedin1970.Lastpreviouseditionapprovedin2019asB537–70(2019).DOI:
10.1520/B0537-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on The last approved version of this historical standard is referenced on
the ASTM website. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B537 − 22
4. Types of Defects 6. Assignment of Protection Rating
4.1 “Protection” defects include crater rusting (Note 2), 6.1 The numerical rating system is based on the area
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 practice, 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, in 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.
photographsandchartsare10by15cm(4by6in.)tofacilitate
comparison with the panel being inspected. The standards
5. Preparation for and Manner of Inspection
represent, as nearly as possible, the maximum amount of
NOTE4—Itmaybedesirabletoexposepanelsfortesteventhoughthey
corrosion permissible for a given rating; there is a standard for
are defective in certain respects before exposure. In that case, an
each rating 1 through 9. A panel worse than the standard for
inspection should be made and recorded before the panels are exposed.
rating 1 would 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.
better than standard (X), but not as good as standard (X+1), it
is rated (X); if somewhat worse than standard (X), but not as
NOTE 5—“Unaided eye” includes wearing of correctional glasses if the
inspector normally wears them.
5.3.1 Optical aids may be used to identify or study defects
once they are found by unaided eye inspection.
TABLE 1 Protection Rating Versus Area of Defect
5.4 Edg
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: B537 − 70 (Reapproved 2019) B537 − 22
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. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This practice covers a preferred method for evaluating the condition of electroplated test panels that have been exposed to
corrosive environments for test purposes. It is based on experience in use of the method with standard 10- by 15-cm (4- by 6-in.)
panels exposed on standard ASTM racks at outdoor test sites in natural atmospheres. It has been used also for rating similar panels
that have been subjected to accelerated tests such as those covered by Practice B117, Method B287, Test Method B368, and Test
Method B380. Any modifications needed to adapt the method to rating actual production parts are not considered in this practice.
1.2 This practice refers only to decorative-protective coatings that are cathodic to the substrate, typified by nickel/chromium or
copper/nickel/chromium on steel or zinc die castings. It is not intended for use with anodic sacrificial coatings such as zinc and
cadmium on steel.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
B117 Practice for Operating Salt Spray (Fog) Apparatus
B287 Method of Acetic Acid-Salt Spray (Fog) Testing (Withdrawn 1987)
B368 Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)
B380 Test Method for Corrosion Testing of Decorative Electrodeposited Coatings by the Corrodkote Procedure
2.2 ASTM Adjunct:
Dot charts (9 charts, 8 ⁄2 by 11 in.) (9 color photos, 3 by 5 in.)
3. Basis of Procedure
3.1 The rating method described in this recommended practice is based on the recognition that typical decorative-protective
This practice is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.05 on Decorative
Coatings.
Current edition approved Oct. 1, 2019Oct. 1, 2022. Published October 2019November 2022. Originally approved in 1970. Last previous edition approved in 20132019
as B537 – 70(2013).(2019). DOI: 10.1520/B0537-70R19.10.1520/B0537-22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
The last approved version of this historical standard is referenced on www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B537 − 22
deposits such as nickel/chromium, with or without a copper undercoat, have two functions: (1) to protect the substrate from
corrosion and thus prevent degradation of appearance caused by basis metal corrosion products (for example, rust and rust stain);
and (2) to itself maintain a satisfactory appearance. Although these functions overlap, they can be evaluated separately, and it is
frequently desirable to do so. Accordingly, this practice assigns separate ratings to (1) appearance as affected by corrosion of the
substrate and (2) appearance as affected by deterioration of the coating itself.
3.2 The rating number assigned to the ability of the coating to protect the substrate from corrosion is called the “protection”
number or rating.
3.3 The rating number assigned to the inspector’s judgment of the overall appearance of the panel, including all defects caused
by the exposure (Note 1), is called the “appearance” number or rating.
NOTE 1—Panels that are not “perfect” even before being exposed 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 given first.
3.5 In addition to recording the numerical rating of a panel, the inspector should note the type(s) and severity of defect(s)
contributing to the rating. This may be done by the use of agreed symbols for the most common defects (Appendix X1) and
abbreviations for degree or severity of these defects.
4. Types of Defects
4.1 “Protection” defects include crater rusting (Note 2), pinhole rusting, rust stain, blisters (Note 3), and any other defects that
involve basis metal corrosion.
NOTE 2—“Rusting” or “rust”“rust,” as used in this documentpractice, includes corrosion products of the substrate and is not confined to iron or steel: the
white corrosion products of zinc die castings and aluminum, for example, are included in this term.
NOTE 3—Blisters on plated zinc die casting usually connote basis metal corrosion;corrosion, but the inspector’s judgment may be required to decide
whether a blister does or does not arise at the substrate-coating interface.
4.2 “Appearance” defects include, thein addition to those caused by basis metal corrosion, all defects that detract from the
appearance (that is, the commercial acceptability) of the panel. Typical are: surface pits, “crow’s feet,” crack patterns, surface stain,
and tarnish.
4.3 Defects developing on exposure that reflect improper preparation or plating should be noted but no attempt should be made
to rate panels showing major amounts of such defects. Peeling of the coating from the substrate, or of one coat from another, is
the principal such defect.
5. Preparation for and Manner of Inspection
NOTE 4—It may be desirable to expose panels for test even though they are defective in certain respects before exposure. In that case, an inspection should
be made and recorded before the panels are exposed.
5.1 Panels may be inspected on the exposure racks or may be removed to a more suitable location if necessary. Lighting during
inspection should be as nearly uniform as possible; direct reflection from sun or clouds should be avoided, and various angles of
inspection should be tried to ensure that defects show up.
5.2 If the condition of the panels allows, inspection should be made in the “as-is” condition. If dirt, salt deposits, and so forth,
make it impractical to inspect them, panels may be sponged with a mild soap solution followed by water rinse; but no pressure
should be exerted in this procedure such as would tend to upgrade the rating by, for example, cleaning off rust or rust stain. Panels
should be allowed to dry before inspecting them.
5.3 Defects to be noted and taken into account in rating panels include only those that can be seen with the unaided eye (Note
5) at normal reading distance.
B537 − 22
NOTE 5—“Unaided eye” includes wearing of correctional glasses if the inspector normally wears them.
5.3.1 Optical aids may be used to identify or study defects once they are found by unaided eye inspection.
5.4 Edge defects, occurring within 6.5 mm ( ⁄4 in.) of the edges of a panel, may be noted in the description but are not counted
in arriving at the numerical rating. Similarly, contact and rack marks, mounting holes, and so forth, should be disregarded.
5.5 Rubbing, polishing, and so forth, of the surface of the panel may be desirable to study one or another aspect of its condition.
Such procedure shall be confined to the minimum area absolutely necessary for the purpose, preferably not more than 1 cm of
a 10- by 15-cm panel.
6. Assignment of Protection Rating
6.1 The numerical rating system is based on the area covered by protection defects, by the following equation:
R 5 3 22 logA (1)
~ !
where R = rating and A = percentage of the total area covered by defects. R is rounded off to the nearest whole number, leading
to the tabulation given in Table 1.
6.1.1 Strict application of the equation given in 6.1 would lead to ratings greater than 10 for panels with extremely small defective
areas. Rating 10, accordingly, is arbitrarily assigned to a panel with no defects, and the equation operates at ratings 9 and below.
6.1.2 If desired, fractional ratings between 9 and 10 may be assigned to panels judged better than 9 but not perfect. Fractional
ratings below 9, although normally not especially useful, may be assigned if desired.
6.2 As an aid in judging the defective area, standards of comparison, consisting of photographs of panels or of dot charts are made
part of this practice. See Appendix X2. These photographs and charts are 10 by 15 cm (4 by 6 in.) to facilitate comparison with
the panel being inspected. The standards represent, as nearly as possible, the maximum amount of corrosion permissible for a given
rating; there is a standard for each rating 1 through 9. A panel worse than the standard for rating 1 would rate 0.
6.2.1 The types of corrosion defects normally encountered differ according to the type of atmospheric exposure. Typical decorative
deposits exposed to marine atmospheres often tend to fail by crater rusting, whereas in industrial atmospheres, they are more likely
to exhibit pinpoint rusting; and the latter atmosphere also tends to be more severe with regard to degradation of the coating system
but somewhat less severe with regard to basis metal corrosion. For this reason, the same standard comparison photographs or charts
are not suitable for use at both types of locations; photographs are more hel
...