ASTM D1735-21

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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: D1735 − 14 D1735 − 21
Standard Practice for
Testing Water Resistance of Coatings Using Water Fog
Apparatus
This standard is issued under the fixed designation D1735; 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 practice covers the basic principles and operating procedures for testing water resistance of coatings in an apparatus
similar to that used for salt spray testing.
1.2 This practice is limited to the methods of obtaining, measuring, and controlling the conditions and procedures of water fog
tests. It does not specify specimen preparation, specific test conditions, or evaluation of results.
NOTE 1—Alternative practices for testing the water resistance of coatings include Practices D870, D2247, and D4585.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 whoever uses the user of this standard to consult and establish appropriate safety safety, health, and healthenvironmental
practices and determine the applicability of regulatory limitations prior to use.
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
D609 Practice for Preparation of Cold-Rolled Steel Panels for Testing Paint, Varnish, Conversion Coatings, and Related Coating
Products
D610 Practice for Evaluating Degree of Rusting on Painted Steel Surfaces
D714 Test Method for Evaluating Degree of Blistering of Paints
D823 Practices for Producing Films of Uniform Thickness of Paint, Coatings and Related Products on Test Panels
D870 Practice for Testing Water Resistance of Coatings Using Water Immersion
D1193 Specification for Reagent Water
D1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
This practice is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.27 on Accelerated Testing.
Current edition approved June 15, 2014Nov. 1, 2021. Published July 2014November 2021. Originally approved in 1960. Last previous edition approved in 20082014 as
D1735 – 08.D1735 – 14. DOI: 10.1520/D1735-14.10.1520/D1735-21.
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.
*A Summary of Changes section appears at the end of this standard
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D1735 − 21
D1730 Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
D2247 Practice for Testing Water Resistance of Coatings in 100 % Relative Humidity
D2616 Test Method for Evaluation of Visual Color Difference With a Gray Scale
D3359 Test Methods for Rating Adhesion by Tape Test
D3363 Test Method for Film Hardness by Pencil Test
D4541 Test Method for Pull-Off Strength of Coatings Using Portable Adhesion Testers
D4585 Practice for Testing Water Resistance of Coatings Using Controlled Condensation
3. Summary of Practice
3.1 Coated specimens are placed in an enclosed chamber to permit free settling of fog on all specimens. The temperature of the
chamber is usually maintained at 38°C (100°F).38 °C (100 °F). The exposure condition is varied by selecting the duration of the
test. Water permeates the coating at rates that are dependent upon the characteristics of the coating. Any effects such as color
change, blisters, loss of adhesion, softening, or embrittlement are observed and reported.
4. Significance and Use
4.1 Water can cause the degradation of coatings, so knowledge of how a coating resists water is helpful in predicting its service
life. Failure in water fog tests may be caused by a number of factors, including a deficiency in the coating itself, contamination
of the substrate, or inadequate surface preparation. The test is therefore useful for evaluating coatings alone or complete coating
systems.
4.2 Water fog tests are used for research and development of coatings and substrate treatments, specification acceptance, and
quality control in manufacturing. These tests usually result in a pass or fail determination, but the degree of failure may also be
measured. A coating system is considered to pass if there is no evidence of water-related failure after a specified period of time.
4.3 Results obtained from the use of water fog tests in accordance with this practice should not be represented as being equivalent
to a period of exposure to water in the natural environment, until the degree of quantitative correlation has been established for
the coating or coating system.
4.4 The test apparatus is similar to that used in Practice B117, and the conversion of the apparatus from salt spray to water fog
testing is feasible. Care should be taken to remove all traces of the salt from the cabinet and reservoir when converting from salt
spray to water fog testing.
5. Apparatus
5.1 Descriptions for the Test Chamber, Test Specimen Supports, and Fog Collecting Devices, are listed under Apparatus Section
in Practice B117.
5.2 Unless otherwise specified, provide for continuous recording, such as a chart recorder or data logger, of the temperature within
the chamber during the exposure period.
6. Test Specimens
6.1 This practice does not cover the preparation of test specimens. The substrate composition and surface preparation, specimen
preparation, and the number of specimens should be agreed upon prior to testing.
NOTE 2—Applicable methods for the preparation of test panels and substrates are given in Practices D609 and D1730. Practices D823 cover application
techniques of the production of uniform films.
6.2 It’s recommended that a control specimen of a paint with known durability be included with each test. Such control specimens
can provide warning of changes in test severity in a given apparatus, and can indicate variations in test severity between different
apparatuses.
6.3 It’s recommended that at least two replicate specimens of each different coating be used, so as to compensate for variations
between specimens and variations in test conditions within the apparatus.
D1735 − 21
7. Procedure
7.1 Fill the reservoir with reagent water conforming to Type IV or better of Specification D1193.
7.2 Heat the water to the desired temperature with the circulating system in operation. If no temperature is specified, heat the water
to 38 6 2°C2 °C (100 6 4°F).4 °F). Maintain the temperature throughout the test.
7.3 Support or suspend specimens 15° from the vertical, with the plane of the specimen parallel to the direction of the fog flow.
Slotted wood The specimens shall be supported or suspended with the surface of interest at an angle to p
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