ASTM B368-21

Standard Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test)

SIGNIFICANCE AND USE
3.1 The CASS test is widely employed and is useful for specification acceptance, simulated service evaluation, manufacturing control, and research and development. It was developed specifically for use with decorative, electrodeposited nickel/chromium and copper/nickel/chromium coatings. Use of the test has improved the quality of electroplated parts and led to the development of new and superior electroplating processes.
SCOPE
1.1 This test method prescribes the conditions required in copper-accelerated acetic acid-salt spray (CASS) testing for specification purposes. The standard does not specify the type of test specimen or exposure periods to be used for a specific product, nor the interpretation to be given to the results.  
1.2 This test method is applicable to evaluating the corrosive performance of decorative copper/nickel/chromium or nickel/chromium coatings on steel, zinc alloys, aluminum alloys, and plastics designed for severe service. It is also applicable to the testing of anodized aluminum. The suitability of this test and correlation of results with service experience should be determined before it is specified for coating systems or materials other than those mentioned in this paragraph.  
Note 1: The following standards are not requirements. They are referenced for information only: Practices B537 and E50, Specifications B456 and B604, and Test Method B602.  
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.4 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. For more specific safety precautionary information see 8.1.  
1.5 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: 31-Mar-2021
• ICS: 77.060 - Corrosion of metals
• Technical Committee: B08 - Metallic and Inorganic Coatings
• Drafting Committee: B08.10 - Test Methods

Relations

• Refers: ASTM E70-24 - Standard Test Method for pH of Aqueous Solutions With the Glass Electrode
• Effective Date: 01-Jan-2024
• Refers: ASTM B604-91(2019) - Standard Specification for Decorative Electroplated Coatings of Copper Plus Nickel Plus Chromium on Plastics
• Effective Date: 01-Oct-2019
• Refers: ASTM B162-99(2019) - Standard Specification for Nickel Plate, Sheet, and Strip
• Effective Date: 01-Apr-2019
• Refers: ASTM E50-17 - Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 01-Sep-2017
• Refers: ASTM E50-11(2016) - Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 01-Aug-2016
• Refers: ASTM E70-07(2015) - Standard Test Method for pH of Aqueous Solutions With the Glass Electrode
• Effective Date: 01-Jun-2015
• Refers: ASTM B604-91(2015) - Standard Specification for Decorative Electroplated Coatings of Copper Plus Nickel Plus Chromium on Plastics
• Effective Date: 01-Mar-2015
• Refers: ASTM B162-99(2014) - Standard Specification for Nickel Plate, Sheet, and Strip
• Effective Date: 01-Oct-2014
• Refers: ASTM B537-70(2013) - Standard Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure
• Effective Date: 01-Dec-2013
• Refers: ASTM B537-70(2012)e1 - Standard Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure
• Effective Date: 01-May-2012
• Refers: ASTM E50-11 - Standard Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
• Effective Date: 15-Oct-2011
• Refers: ASTM B117-11 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Oct-2011
• Refers: ASTM B456-11 - Standard Specification for Electrodeposited Coatings of Copper Plus Nickel Plus<br> Chromium and Nickel Plus Chromium
• Effective Date: 01-Jun-2011
• Refers: ASTM B456-11e1 - Standard Specification for Electrodeposited Coatings of Copper Plus Nickel Plus<br> Chromium and Nickel Plus Chromium
• Effective Date: 01-Jun-2011
• Refers: ASTM B602-88(2010) - Standard Test Method for Attribute Sampling of Metallic and Inorganic Coatings
• Effective Date: 01-Apr-2010

Overview

ASTM B368-21: Standard Test Method for Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing (CASS Test) is a widely used international standard developed by ASTM International. Specifically designed for evaluating the corrosion resistance of decorative electroplated coatings, it prescribes the laboratory conditions for the CASS test, which simulates severe service environments. The standard focuses on testing decorative copper/nickel/chromium and nickel/chromium coatings on metals and plastics, and is also applicable to anodized aluminum.

Adherence to ASTM B368-21 has improved the manufacturing quality of electroplated parts, supported research and development, and enabled better control of electrodeposited coating processes. It plays a key role in quality assurance, specification acceptance, and simulated service evaluations within the corrosion testing community.

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Key Topics

• Purpose and Scope

  • Prescribes the conditions for CASS testing to evaluate the corrosive performance of coatings.
  • Applicable to decorative copper/nickel/chromium or nickel/chromium coatings, and to anodized aluminum.
  • Suitable for testing coatings on steel, zinc alloys, aluminum alloys, and plastics designed for severe service.

• Apparatus and Test Solution

  • Requires a fog chamber with specific temperature and air pressure control.
  • Utilizes a test solution of sodium chloride, copper chloride, and acetic acid, with pH and specific gravity monitored closely.

• Specimen Preparation and Test Procedure

  • Details proper cleaning, handling, and positioning of test pieces in the chamber to ensure valid results.
  • Emphasizes masking of edges and prevention of cross-contamination.

• Calibration and Verification

  • Includes procedures for verifying the corrosiveness of the chamber environment using nickel test panels.
  • Requires regular calibration to ensure ongoing test reliability.

• Safety and Compliance

  • Users are responsible for maintaining compliance with safety, health, and environmental regulations.
  • The procedure follows international standardization principles.

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Applications

ASTM B368-21 CASS testing is essential for industries requiring durable and corrosion-resistant decorative coatings, such as automotive, hardware, plumbing, and consumer goods. Practical applications include:

• Specification Acceptance: Demonstrates conformity to quality standards for finished electroplated products.
• Simulated Service Testing: Assesses expected performance of coatings in harsh or aggressive environments.
• Manufacturing Quality Control: Detects process issues and ensures consistency in production.
• Research and Development: Supports the development of new coating processes and improved materials.
• Testing of Anodized Aluminum: Provides a standardized approach for evaluating corrosion resistance in anodized surfaces.

The test ensures that only coatings with proven resistance to corrosion under severe conditions are used, reducing product failure and enhancing customer satisfaction.

---

Related Standards

Several related ASTM standards provide additional guidance on coating evaluation and salt spray testing:

• ASTM B117 - Practice for Operating Salt Spray (Fog) Apparatus
• ASTM B456 - Specification for Electrodeposited Coatings of Copper Plus Nickel Plus Chromium and Nickel Plus Chromium
• ASTM B537 - Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure
• ASTM B604 - Specification for Decorative Electroplated Coatings on Plastics
• ASTM B602 - Test Method for Attribute Sampling of Metallic and Inorganic Coatings
• ASTM D1193 - Specification for Reagent Water (used in preparing test solutions)
• ASTM E50 - Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals

These standards, referenced for information, complement ASTM B368-21 by providing procedures, requirements, and best practices for consistent, reliable corrosion testing and evaluation.

Implementing ASTM B368-21 helps organizations advance quality assurance programs and maintain compliance with international coating and corrosion performance standards.

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: B368 − 21
Standard Test Method for
Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing
(CASS Test)
This standard is issued under the fixed designation B368; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope 2. Referenced Documents
1.1 This test method prescribes the conditions required in 2.1 ASTM Standards:
copper-accelerated acetic acid-salt spray (CASS) testing for B117 Practice for Operating Salt Spray (Fog) Apparatus
specification purposes. The standard does not specify the type B162 Specification for Nickel Plate, Sheet, and Strip
of test specimen or exposure periods to be used for a specific B456 Specification for Electrodeposited Coatings of Copper
product, nor the interpretation to be given to the results. Plus Nickel Plus Chromium and Nickel Plus Chromium
B537 Practice for Rating of Electroplated Panels Subjected
1.2 This test method is applicable to evaluating the corro-
to Atmospheric Exposure
sive performance of decorative copper/nickel/chromium or
B602 Test Method for Attribute Sampling of Metallic and
nickel/chromium coatings on steel, zinc alloys, aluminum
Inorganic Coatings
alloys, and plastics designed for severe service. It is also
B604 Specification for Decorative Electroplated Coatings of
applicable to the testing of anodized aluminum. The suitability
Copper Plus Nickel Plus Chromium on Plastics
of this test and correlation of results with service experience
D1193 Specification for Reagent Water
should be determined before it is specified for coating systems
E50 Practices for Apparatus, Reagents, and Safety Consid-
or materials other than those mentioned in this paragraph.
erations for Chemical Analysis of Metals, Ores, and
NOTE 1—The following standards are not requirements. They are
Related Materials
referenced for information only: Practices B537 and E50, Specifications
E70 Test Method for pH of Aqueous Solutions With the
B456 and B604, and Test Method B602.
Glass Electrode
1.3 Units—The values stated in SI units are to be regarded
as standard. No other units of measurement are included in this
3. Significance and Use
standard.
3.1 The CASS test is widely employed and is useful for
1.4 This standard does not purport to address all of the
specification acceptance, simulated service evaluation, manu-
safety concerns, if any, associated with its use. It is the
facturing control, and research and development. It was devel-
responsibility of the user of this standard to establish appro-
oped specifically for use with decorative, electrodeposited
priate safety, health, and environmental practices and deter-
nickel/chromiumandcopper/nickel/chromiumcoatings.Useof
mine the applicability of regulatory limitations prior to use.
the test has improved the quality of electroplated parts and led
For more specific safety precautionary information see 8.1.
to the development of new and superior electroplating pro-
1.5 This international standard was developed in accor-
cesses.
dance with internationally recognized principles on standard-
4. Apparatus
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
4.1 The apparatus required for the CASS test consists of a
mendations issued by the World Trade Organization Technical
fog chamber, a salt-solution reservoir, a supply of compressed
Barriers to Trade (TBT) Committee.
air, one or more atomizing nozzles, specimen supports, provi-
sion for heating the chamber, and necessary means of control.
4.2 The size and detailed construction of the apparatus are
This test method is under the jurisdiction ofASTM Committee B08 on Metallic
optional, provided the conditions meet the requirements of this
and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on
Test Methods.
Current edition approved April 1, 2021. Published April 2021. Originally
approvedin1961.Lastpreviouseditionapprovedin2014asB368 – 09(2014).DOI: For referenced ASTM standards, visit the ASTM website, www.astm.org, or
10.1520/B0368-21. contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
The CASS test was developed by the initiative of the Research Board of the Standards volume information, refer to the standard’s Document Summary page on
American Electroplaters Society under AES Project 15. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B368 − 21
pressure of a nozzle has not been determined with certainty, control of
test method. The construction of the apparatus is described in
fluctuationintheairpressurewithin 60.0007MPabyinstallingapressure
the appendix of Test Method B117. For the CASS test,
regulator valve minimizes the possibility that the nozzle will be operated
however, the requirements for air pressure and temperature are
at its critical pressure. Pressure of 0.10 6 0.02 MPa has been found
typically 0.08 to 0.12 MPa and 60 to 65 °C, respectively. The
satisfactory.
actual air pressure will be that required to produce the proper
7. Test Specimens
collection rate (see 8.3.1).
7.1 The type and number of test specimens to be used, as
4.3 The apparatus shall be constructed so that drops of
well as the criteria for the evaluation of the test results, shall be
solution that accumulate on the ceiling or cover of the chamber
defined in the specifications covering the material or product
do not fall on the specimens being tested. Drops of solution
being tested or shall be mutually agreed upon between the
that fall from the specimens shall not be returned to the
purchaser and the supplier.
solution reservoir for respraying.
4.4 Materials of construction shall not affect the corrosive- 8. Procedure
ness of the fog, nor be themselves corroded by the fog.
8.1 Preparation of Test Specimens— Clean metallic and
metallic coated specimens. Unless otherwise agreed upon,
5. Test Solution
clean decorative copper/nickel/chromium or nickel/chromium
5.1 Prepare the salt solution by dissolving 5 parts by weight
coatings immediately before testing by wiping significant
of salt in 95 parts of water conforming to Specification D1193,
surfaces with a cotton pad saturated with a slurry containing 10
TypeIV.Thesaltshallbesodiumchloride(NaCl),ACSreagent
gofpuremagnesiumoxidepowder(ACSreagentgrade)in100
grade, or equivalent. The pH of this solution shall be between
mL of distilled water. Upon rinsing in warm running water, be
6.0and7.0.Impuritiesorcontaminationofeitherthesaltorthe
sure that the clean surface is free of water break. Anodized
water, or both, shall be suspected if the pH is outside of this
aluminum parts may be cleaned with inhibited 1,1,1-
range (Note 2). No adjustment should be made.
trichloroethane or other suitable organic solvent (seeWarning).
Do not clean organic and other nonmetallic coated specimens.
5.2 Add 0.25 g of reagent grade copper chloride
Other methods of cleaning, such as the use of a nitric-acid
(CuCl ·2H O) to each liter of the salt solution; dissolve and
2 2
solution for the chemical cleaning or passivation of stainless
mix thoroughly.
steel specimens, are permissible when agreed upon between
5.3 The pH of the salt-copper solution shall be adjusted to
the purchaser and the supplier. Take care that the specimens
the range of 3.1 to 3.3, as measured on a sample of the
after cleaning are not recontaminated by excessive or careless
collected spray, by the addition of glacial acetic acid, ACS
handling. Protect the cut edges of plated, coated, or multilay-
reagent grade, or equivalent (Note 3). The pH measurement
ered materials and areas containing identification marks or in
shall be made electrometrically at 25 °C. Before the solution is
contact with the racks or supports with a coating that is stable
atomized, it shall be free of suspended solids (Note 4).
under the conditions of the test, such as wax, stop-off lacquer,
NOTE 2—Reference Practice B117 and Test Method E70 for require-
or pressure-sensitive tape. (Warning—1,1,1-Trichloroethane
mentsonsalt.ThemadeupCASSsolutionshouldbeadjustedtoaspecific
should be used in a well-ventilated area away from open
gravity of 1.030 to 1.040, when measured at a temperature of 25 °C, will
flames.)
meet the concentration requirement. It is suggested that a daily check be
made.
8.2 Positioning of Specimens—Positionthespecimensinthe
NOTE 3—The initial solution may be adjusted to a pH that gives the
CASS test chamber during the test so that the following
proper pH range in the collected solution.Adjustment of the initial pH for
conditions are met:
makeup solution is based upon the requirements to maintain the required
8.2.1 Support or suspend the specimens 15 – 30° from the
pH of the collected samples. If less than 1.3 or more than 1.6 mL of the
glacial acetic acid are required per litre of sodium chloride and copper vertical and preferably parallel to the principal direction of
solution to attain the specified pH, some discrepancy in the system may be
horizontal flow of fog through the chamber, based upon the
suspected (the purity of the water or salt, or both; the accuracy of the pH
dominant surface being tested, avoiding pooling of solution on
meter; the general cleanliness of the system; etc.).
the sample. See Note 8 on automobile parts.
NOTE 4—The freshly prepared salt solution may be filtered or decanted
8.2.2 The top of the specimen shall not be higher than the
before it is placed in the reservoir, or the end of the tube leading from the
solution to the atomizer may be covered with a double layer of cheese top of the collection tubes.
cloth to prevent plugging of the nozzle.
8.2.3 Make sure the specimens do not come in contact with
each other or any other metallic material or any material
6. Air Supply
capable of acting as a wick.
6.1 The compressed air supply to the nozzle or nozzles for
8.2.4 Placeeachspecimensoastopermitfreesettlingoffog
atomizing the test solution shall be free of oil and dirt (Note 5).
on all specimens.
Pressure shall be adequate to provide a specified condensate
8.2.5 Make sure the salt solution from one specimen does
rate.
not drip on any other specimen.
8.2.6 Place the specimens in the chamber just prior to
NOTE 5—The air supply can be freed of oil and dirt by passing it
bringing the test chamber to the required temperature and
through a water scrubber or at least 60 cm of suitable cleaning material,
such as sheep’s wool, excelsior, slag wool, or activated alumina. Com- turning on the air, since storage in an idle chamber overnight,
mercial filters for compressed air may be used.
or for other significant length of time, can affect test results.
NOTE 6—Atomizing nozzles may have a critical pressure, at which an
abnormal increase in the corrosiveness of the salt fog occurs. If the critical NOTE 7—Suitable materials for the construction or coating of racks and
B368 − 21
supports are glass, rubber, plastic, or suitably coated wood. Bare metal NOTE 12—A solution having a specific gravity of from 1.030 to 1.040,
should not be used. Specimens are preferably supported from the bottom when measured at 25 °C, will meet the concentration requirement. The
ortheside.Slottedwoodenstripsaresuitableforthesupportofflatpanels. concentration may also be determined as follows: Dilute 5 mL of the
Suspension from glass hooks or waxed string may be used as long as the collected solution to 100 mL with distilled water and mix thoroughly;
specified position of the specimens is obtained. If necessary, such pipet a 10 mLaliquot into an evaporating dish or casserole; add 40 mLof
suspension may be made by means of secondar
...

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: B368 − 09 (Reapproved 2014) B368 − 21
Standard Test Method for
Copper-Accelerated Acetic Acid-Salt Spray (Fog) Testing
(CASS Test)
This standard is issued under the fixed designation B368; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope
1.1 This test method prescribes the conditions required in copper-accelerated acetic acid-salt spray (CASS) testing for
specification purposes. The standard does not specify the type of test specimen or exposure periods to be used for a specific
product, nor the interpretation to be given to the results.
1.2 This test method is applicable to evaluating the corrosive performance of decorative copper/nickel/chromium or nickel/
chromium coatings on steel, zinc alloys, aluminum alloys, and plastics designed for severe service. It is also applicable to the
testing of anodized aluminum. The suitability of this test and correlation of results with service experience should be determined
before it is specified for coating systems or materials other than those mentioned in this paragraph.
NOTE 1—The following standards are not requirements. They are referenced for information only: Practices B537 and E50, Specifications B456 and B604,
and Test Method B602.
1.3 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.4 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 safety, health, and healthenvironmental practices and determine the
applicability of regulatory limitations prior to use. For more specific safety precautionary information see 8.1.
1.5 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
B162 Specification for Nickel Plate, Sheet, and Strip
B456 Specification for Electrodeposited Coatings of Copper Plus Nickel Plus Chromium and Nickel Plus Chromium
This test method is under the jurisdiction of ASTM Committee B08 on Metallic and Inorganic Coatings and is the direct responsibility of Subcommittee B08.10 on Test
Methods.
Current edition approved May 1, 2014April 1, 2021. Published May 2014April 2021. Originally approved in 1961. Last previous edition approved in 20092014 as
B368 – 09.B368 – 09(2014). DOI: 10.1520/B0368-09R14.10.1520/B0368-21.
The CASS test was developed by the initiative of the Research Board of the American Electroplaters Society under AES Project 15.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
B368 − 21
B537 Practice for Rating of Electroplated Panels Subjected to Atmospheric Exposure
B602 Test Method for Attribute Sampling of Metallic and Inorganic Coatings
B604 Specification for Decorative Electroplated Coatings of Copper Plus Nickel Plus Chromium on Plastics
D1193 Specification for Reagent Water
E50 Practices for Apparatus, Reagents, and Safety Considerations for Chemical Analysis of Metals, Ores, and Related Materials
E70 Test Method for pH of Aqueous Solutions With the Glass Electrode
3. Significance and Use
3.1 The CASS test is widely employed and is useful for specification acceptance, simulated service evaluation, manufacturing
control, and research and development. It was developed specifically for use with decorative, electrodeposited nickel/chromium
and copper/nickel/chromium coatings. Use of the test has improved the quality of electroplated parts and led to the development
of new and superior electroplating processes.
4. Apparatus
4.1 The apparatus required for the CASS test consists of a fog chamber, a salt-solution reservoir, a supply of compressed air, one
or more atomizing nozzles, specimen supports, provision for heating the chamber, and necessary means of control.
4.2 The size and detailed construction of the apparatus are optional, provided the conditions meet the requirements of this test
method. The construction of the apparatus is described in the appendix of Test Method B117. For the CASS test, however, the
requirements for air pressure and temperature are typically 0.08 to 0.12 MPa and 60 to 65°C,65 °C, respectively. The actual air
pressure will be that required to produce the proper collection rate (see 8.3.1).
4.3 The apparatus shall be constructed so that drops of solution that accumulate on the ceiling or cover of the chamber do not fall
on the specimens being tested. Drops of solution that fall from the specimens shall not be returned to the solution reservoir for
respraying.
4.4 Materials of construction shall not affect the corrosiveness of the fog, nor be themselves corroded by the fog.
5. Test Solution
5.1 Prepare the salt solution by dissolving 5 parts by weight of salt in 95 parts of water conforming to Specification D1193, Type
IV. The salt shall be sodium chloride (NaCl), ACS reagent grade, or equivalent. The pH of this solution shall be between 6.0 and
7.0. Impurities or contamination of either the salt or the water, or both, shall be suspected if the pH is outside of this range (Note
2). No adjustment should be made.
5.2 Add 0.25 g of reagent grade copper chloride (CuCl ·2H O) to each liter of the salt solution; dissolve and mix thoroughly.
2 2
5.3 The pH of the salt-copper solution shall be adjusted to the range of 3.1 to 3.3, as measured on a sample of the collected spray,
by the addition of glacial acetic acid, ACS reagent grade, or equivalent (Note 3). The pH measurement shall be made
electrometrically at 25°C.25 °C. Before the solution is atomized, it shall be free of suspended solids (Note 4).
NOTE 2—Reference Practice B117 and Test Method E70 for requirements on salt. The made up CASS solution should be adjusted to a specific gravity
of 1.030 to 1.040, when measured at a temperature of 25°C,25 °C, will meet the concentration requirement. It is suggested that a daily check be made.
NOTE 3—The initial solution may be adjusted to a pH that gives the proper pH range in the collected solution. Adjustment of the initial pH for makeup
solution is based upon the requirements to maintain the required pH of the collected samples. If less than 1.3 or more than 1.6 mL of the glacial acetic
acid are required per litre of sodium chloride and copper solution to attain the specified pH, some discrepancy in the system may be suspected (the purity
of the water or salt, or both; the accuracy of the pH meter; the general cleanliness of the system; etc.).
NOTE 4—The freshly prepared salt solution may be filtered or decanted before it is placed in the reservoir, or the end of the tube leading from the solution
to the atomizer may be covered with a double layer of cheese cloth to prevent plugging of the nozzle.
6. Air Supply
6.1 The compressed air supply to the nozzle or nozzles for atomizing the test solution shall be free of oil and dirt (Note 5). Pressure
shall be adequate to provide a specified condensate rate.
B368 − 21
NOTE 5—The air supply can be freed of oil and dirt by passing it through a water scrubber or at least 60 cm of suitable cleaning material, such as sheep’s
wool, excelsior, slag wool, or activated alumina. Commercial filters for compressed air may be used.
NOTE 6—Atomizing nozzles may have a critical pressure, at which an abnormal increase in the corrosiveness of the salt fog occurs. If the critical pressure
of a nozzle has not been determined with certainty, control of fluctuation in the air pressure within 60.0007 MPa by installing a pressure regulator valve
minimizes the possibility that the nozzle will be operated at its critical pressure. Pressure of 0.10 6 0.02 MPa has been found satisfactory.
7. Test Specimens
7.1 The type and number of test specimens to be used, as well as the criteria for the evaluation of the test results, shall be defined
in the specifications covering the material or product being tested or shall be mutually agreed upon between the purchaser and the
supplier.
8. Procedure
8.1 Preparation of Test Specimens— Clean metallic and metallic coated specimens. Unless otherwise agreed upon, clean
decorative copper/nickel/chromium or nickel/chromium coatings immediately before testing by wiping significant surfaces with
a cotton pad saturated with a slurry containing 10 g of pure magnesium oxide powder (ACS reagent grade) in 100 mL of distilled
water. Upon rinsing in warm running water, be sure that the clean surface is free of water break. Anodized aluminum parts may
be cleaned with inhibited 1,1,1-trichloroethane or other suitable organic solvent (see Warning). Do not clean organic and other
nonmetallic coated specimens. Other methods of cleaning, such as the use of a nitric-acid solution for the chemical cleaning or
passivation of stainless steel specimens, are permissible when agreed upon between the purchaser and the supplier. Take care that
the specimens after cleaning are not recontaminated by excessive or careless handling. Protect the cut edges of plated, coated, or
multilayered materials and areas containing identification marks or in contact with the racks or supports with a coating that is stable
under the conditions of the test, such as wax, stop-off lacquer, or pressure-sensitive tape. (Warning—1,1,1-Trichloroethane should
be used in a well-ventilated area away from open flames.)
8.2 Positioning of Specimens—Position the specimens in the CASS test chamber during the test so that the following conditions
are met:
8.2.1 Support or suspend the specimens 15 – 30° from the vertical and preferably parallel to the principal direction of horizontal
flow of fog through the chamber, based upon the dominant surface being tested, avoiding pooling of solution on the sample. See
Note 8 on automobile parts.
8.2.2 The top of the specimen shall not be higher than the top of the collection tubes.
8.2.3 Make sure the specimens do not come in contact with each other or any other metallic material or any material capable of
acting as a wick.
8.2.4 Place each specimen so as to permit free settling of fog on all specimens.
8.2.5 Make sure the salt solution from one specimen does not drip on any other specimen.
8.2.6 Place the specimens in the chamber just prior to bringing the test chamber to the required temperature and turning on the
air, since storage in an idle chamber overnight, or for other significant length of time, can affect test results.
NOTE 7—Suitable materials for the construction or coating of racks and supports are glass, rubber, plastic, or suitably coated wood. Bare metal should
not be used. Specimens are preferably supported from the bottom or the side. Slotted wooden strips are suitable for the support of flat panels. Suspension
from glass hooks or waxed string may be used as long as the specified position of the specimens is obtained. If necessary, such suspension may be made
by means of secondary support at the bottom of the specimens.
NOTE 8—Support suspendsuspended automobile parts, however, so as to expose all significant surfaces at the general level of the condensate collectors.
If the position on the automobile is vertical, place the part in an incline position 15-30° from vertical to allow surface wetting by the condensate. If the
posi
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