ASTM D2803-09(2015)
(Guide)Standard Guide for Testing Filiform Corrosion Resistance of Organic Coatings on Metal
Standard Guide for Testing Filiform Corrosion Resistance of Organic Coatings on Metal
SIGNIFICANCE AND USE
5.1 Some organic coatings applied to metal substrates exhibit filiform corrosion when there is a break in the coating film and the relative humidity is in the 70 to 95 % range.
5.2 This guide can be used to determine the susceptibility of organic coated metal substrates to the formation of filiform corrosion.
SCOPE
1.1 This guide covers three procedures for determining the susceptibility of organic-coated metal substrates to formation of filiform corrosion.
1.2 This guide is limited to the determination of whether filiform corrosion will occur between the organic coating and substrate.
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 problems, if any, 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.
Note 1: Procedure B of this standard is equivalent to ISO 4623.
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Designation: D2803 − 09 (Reapproved 2015)
Standard Guide for Testing
Filiform Corrosion Resistance of Organic Coatings on
Metal
This standard is issued under the fixed designation D2803; 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 Aluminum-Alloy Surfaces for Painting
D7091 Practice for Nondestructive Measurement of Dry
1.1 This guide covers three procedures for determining the
Film Thickness of Nonmagnetic Coatings Applied to
susceptibility of organic-coated metal substrates to formation
Ferrous Metals and Nonmagnetic, Nonconductive Coat-
of filiform corrosion.
ings Applied to Non-Ferrous Metals
1.2 This guide is limited to the determination of whether
E104 Practice for Maintaining Constant Relative Humidity
filiform corrosion will occur between the organic coating and
by Means of Aqueous Solutions
substrate.
2.2 International Standard:
1.3 The values stated in SI units are to be regarded as the ISO 4623–1 Paints and Varnishes—Determination of resis-
tance to filiform corrosion–Part 1: On steel
standard. The values given in parentheses are for information
only. ISO 4623–2 Paints and Varnishes—Determination of resis-
tance to filiform corrosion–Part 2: On aluminum
1.4 This standard does not purport to address all of the
ISO 4628–10 Paints and Varnishes—Evaluation of degrada-
safety problems, if any, associated with its use. It is the
tion of coatings—Designation of quantity and size of
responsibility of the user of this standard to establish appro-
defectsandofintensityofchanges–Part10:Assessmentof
priate safety and health practices and determine the applica-
filiform corrosion
bility of regulatory limitations prior to use.
NOTE 1—Procedure B of this standard is equivalent to ISO 4623. 3. Terminology
3.1 Definitions:
2. Referenced Documents
3.1.1 filiform corrosion, n—a special type of corrosion that
2.1 ASTM Standards:
occurs under coatings on metal substrates that is characterized
B117 Practice for Operating Salt Spray (Fog) Apparatus
by a definite threadlike structure and directional growth.
D609 Practice for Preparation of Cold-Rolled Steel Panels
3.1.1.1 Discussion—Filiform corrosion usually occurs be-
for Testing Paint, Varnish, Conversion Coatings, and
tween 20 and 35°C (70 and 95°F), with a corresponding
Related Coating Products
relative humidity range of 60 to 95 %; above 95 % humidity,
D823 Practices for Producing Films of Uniform Thickness
blistering rather than filiform corrosion may occur.
of Paint, Varnish, and Related Products on Test Panels
4. Summary of Method
D1005 Test Method for Measurement of Dry-Film Thick-
ness of Organic Coatings Using Micrometers
4.1 Coated metal specimens are scribed and placed in a
D1654 Test Method for Evaluation of Painted or Coated
corrosive atmosphere to initiate corrosion. The specimens are
Specimens Subjected to Corrosive Environments
then exposed to controlled temperature and humidity condi-
D1730 Practices for Preparation of Aluminum and
tions known to be conducive to filiform corrosion.
4.2 In Procedure A, panels are subjected to a preliminary
exposure in the salt spray cabinet to initiate corrosion, rinsed,
This guide is under the jurisdiction of ASTM Committee D01 on Paint and
Related Coatings, Materials, and Applications and is the direct responsibility of
andplacedinahumiditycabinet.InProcedureB,basedonISO
Subcommittee D01.27 on Accelerated Testing.
4623, panels are either exposed to salt spray or dipped in a salt
Current edition approved June 1, 2015. Published June 2015. Originally
solution but not rinsed before placing in the humidity cabinet
approved in 1969. Last previous addition approved in 2009 as D2803 – 09. DOI:
10.1520/D2803-09R15. operated at a higher temperature than in Procedure A. In
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 Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
the ASTM website. 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2803 − 09 (2015)
Procedure C, specimens are exposed as in Procedure A except 9. Procedure A
the humidity cabinet is operated at a higher temperature.
9.1 Expose the test specimens to the salt-fog atmosphere in
4.3 The procedures contained in this guide differ signifi-
accordance with Practice B117 for at least 4 h and not more
cantly in method of initiation, and or temperature, or both, and
than 24 h, or as agreed upon between the producer and user.
humidity of exposure and therefore may not yield comparable
9.2 Remove from the salt-fog cabinet and thoroughly rinse
results.
with distilled or demineralized water. Do not permit specimens
to dry before placing in the humidity cabinet.
5. Significance and Use
9.3 Place the specimens in the humidity cabinet so that they
5.1 Some organic coatings applied to metal substrates ex-
are no closer together than 40 mm (1.5 in.) and not in contact
hibitfiliformcorrosionwhenthereisabreakinthecoatingfilm
with any metal. Set the cabinet to operate at 25°C (77°F) and
and the relative humidity is in the 70 to 95 % range.
85 % relative humidity unless otherwise agreed upon between
5.2 This guide can be used to determine the susceptibility of
theproduceranduser.Theallowedoperationallimitsare 62°C
organic coated metal substrates to the formation of filiform
(63.5°F) and 610 % relative humidity.
corrosion.
NOTE6—Therecommendedmeansofmaintainingthespecifiedrelative
humidity is to utilize trays of saturated potassium chromate solution (650
6. Apparatus
g/L). Practice E104 describes other methods for maintaining relative
6.1 Salt-Spray Chamber as described in Practice B117, for
humidity, but they may affect the degree and rate of filiform corrosion.
salt-spray (fog) testing.
9.4 Inspect the specimens at intervals of approximately 168
NOTE 2—The preferred initiator of corrosion at the scribe is the salt-fog h for development of threadlike filaments from the scribe.
atmosphere described in Practice B117. Exposure of the specimens for 2
Exercise care to maintain wetness of specimens during
to4hina closed cabinet to the atmosphere above a 1 % acetic acid
inspection, since drying stops the original pattern of filiform
solution is an acceptable alternative.
corrosion. New filiform may develop on continued exposure
6.2 Humidity Cabinet—Any cabinet with suitable tem
...
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: D2803 − 09 D2803 − 09 (Reapproved 2015)
Standard Guide for Testing
Filiform Corrosion Resistance of Organic Coatings on
Metal
This standard is issued under the fixed designation D2803; 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*Scope
1.1 This guide covers three procedures for determining the susceptibility of organic-coated metal substrates to formation of
filiform corrosion.
1.2 This guide is limited to the determination of whether filiform corrosion will occur between the organic coating and substrate.
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 problems, if any, 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.
NOTE 1—Procedure B of this standard is equivalent to ISO 4623.
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
D823 Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
D1005 Test Method for Measurement of Dry-Film Thickness of Organic Coatings Using Micrometers
D1654 Test Method for Evaluation of Painted or Coated Specimens Subjected to Corrosive Environments
D1730 Practices for Preparation of Aluminum and Aluminum-Alloy Surfaces for Painting
D7091 Practice for Nondestructive Measurement of Dry Film Thickness of Nonmagnetic Coatings Applied to Ferrous Metals
and Nonmagnetic, Nonconductive Coatings Applied to Non-Ferrous Metals
E104 Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions
2.2 International Standard:
ISO 4623–1 Paints and Varnishes—Determination of resistance to filiform corrosion–Part 1: On steel
ISO 4623–2 Paints and Varnishes—Determination of resistance to filiform corrosion–Part 2: On aluminum
ISO 4628–10 Paints and Varnishes—Evaluation of degradation of coatings—Designation of quantity and size of defects and of
intensity of changes–Part 10: Assessment of filiform corrosion
3. Terminology
3.1 Definitions:
3.1.1 filiform corrosion, n—a special type of corrosion that occurs under coatings on metal substrates that is characterized by
a definite threadlike structure and directional growth.
This guide 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 Aug. 1, 2009June 1, 2015. Published September 2009June 2015. Originally approved in 1969. Last previous addition approved in 20032009 as
D2803 - 03.D2803 – 09. DOI: 10.1520/D2803-09.10.1520/D2803-09R15.
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’sstandard’s Document Summary page on the ASTM website.
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2803 − 09 (2015)
3.1.1.1 Discussion—
Filiform corrosion usually occurs between 20 and 35°C (70 and 95°F), with a corresponding relative humidity range of 60 to 95 %;
above 95 % humidity, blistering rather than filiform corrosion may occur.
4. Summary of Method
4.1 Coated metal specimens are scribed and placed in a corrosive atmosphere to initiate corrosion. The specimens are then
exposed to controlled temperature and humidity conditions known to be conducive to filiform corrosion.
4.2 In Procedure A, panels are subjected to a preliminary exposure in the salt spray cabinet to initiate corrosion, rinsed, and
placed in a humidity cabinet. In Procedure B, based on ISO 4623, panels are either exposed to salt spray or dipped in a salt solution
but not rinsed before placing in the humidity cabinet operated at a higher temperature than in Procedure A. In Procedure C,
specimens are exposed as in Procedure A except the humidity cabinet is operated at a higher temperature.
4.3 The procedures contained in this guide differ significantly in method of initiation, and or temperature, or both, and humidity
of exposure and therefore may not yield comparable results.
5. Significance and Use
5.1 Some organic coatings applied to metal substrates exhibit filiform corrosion when there is a break in the coating film and
the relative humidity is in the 70 to 95 % range.
5.2 This guide can be used to determine the susceptibility of organic coated metal substrates to the formation of filiform
corrosion.
6. Apparatus
6.1 Salt-Spray Chamber as described in Practice B117, for salt-spray (fog) testing.
NOTE 2—The preferred initiator of corrosion at the scribe is the salt-fog atmosphere described in Practice B117. Exposure of the specimens for 2 to
4 h in a closed cabinet to the atmosphere above a 1 % acetic acid solution is an acceptable alternative.
6.2 Humidity Cabinet—Any cabinet with suitable temperature and humidity controls with air circulation may be used. The size
and detailed construction of the apparatus are optional, provided the conditions meet the requirements of this method.
7. Test Specimen
7.1 The composition, surface preparation, and number of test specimens shall be agreed upon between the producer and the user.
Steel is the preferred substrate, but other metals such as aluminum, copper magnesium, and stainless steel may be used. Zinc and
zinc-coated steel are not recommended because filiform corrosion generally does not occur on zinc.
NOTE 3—Applicable test panel description and surface preparation methods are given in Practice D609 and Practices D1730.
7.2 Preparation of Test Specimens—The method of application, film thickness, curing, and conditioning shall be agreed upon
between the producer and user.
NOTE 4—Practices D823 gives application methods that can be used to produce films of uniform film thickness.
NOTE 5—Test Method D1005 and Practice D7091 give procedures that can be used for measurement of dry film thickness.
7.3 Scribe the test specimen in accordance with Test Method D1654 or as agreed upon between the producer and user.
7.4 The back and edges of the panel should be protected with an anti-corrosion coating or tape, unless edge failure is being
evaluated.
8. Use of Control or Reference Materials
8.1 When several coatings are being compared, select a coating as a control. Apply the control c
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