ISO 3210
(Main)Anodizing of aluminium and its alloys — Assessment of quality of sealed anodic oxidation coatings by measurement of the loss of mass after immersion in acid solution(s)
Anodizing of aluminium and its alloys — Assessment of quality of sealed anodic oxidation coatings by measurement of the loss of mass after immersion in acid solution(s)
ISO 3210:2017 specifies methods of assessing the quality of sealed anodic oxidation coatings on aluminium and its alloys by measurement of the loss of mass after immersion in acid solution(s). It consists of the following two methods. - Method 1: Assessment of quality of sealed anodic oxidation coatings by measurement of the loss of mass after immersion in a phosphoric acid based solution without prior acid treatment. - Method 2: Assessment of quality of sealed anodic oxidation coatings by measurement of the loss of mass after immersion in a phosphoric acid based solution with prior acid treatment. Method 1 is applicable to anodic oxidation coatings intended for decorative or protective purposes or where resistance to staining is important. Method 2 is applicable to anodic oxidation coatings intended for outdoor architectural purposes. For less severe applications, Method 1 can be more suitable. The methods are not applicable to the following: - hard-type anodic oxidation coatings which normally are not sealed; - anodic oxidation coatings that have been sealed only in dichromate solutions; - anodic oxidation coatings produced in chromic acid solutions; - anodic oxidation coatings that have undergone treatment to render them hydrophobic. NOTE 1 The methods assess the quality of hydrothermal sealing applied to anodized aluminium. They can be appropriate for other sealing methods. NOTE 2 The methods are destructive and can serve as reference methods in case of doubt or dispute regarding the results of the test for loss of absorptive power (see ISO 2143) or the measurement of admittance (see ISO 2931).
Anodisation de l'aluminium et de ses alliages — Évaluation de la qualité des couches anodiques colmatées par mesurage de la perte de masse après immersion en solution(s) acide(s)
L'ISO 3210 :2017 spécifie des méthodes d'évaluation de la qualité des couches anodiques colmatées sur aluminium et alliages d'aluminium par mesurage de la perte de masse après immersion en solution(s) acide(s). Il comprend les deux méthodes suivantes: - Méthode 1: Évaluation de la qualité des couches anodiques colmatées par mesurage de la perte de masse après immersion dans une solution à base d'acide phosphorique, sans traitement acide préalable; - Méthode 2: Évaluation de la qualité des couches anodiques colmatées par mesurage de la perte de masse après immersion dans une solution à base d'acide phosphorique, avec traitement acide préalable. La méthode 1 s'applique aux couches anodiques utilisées à des fins décoratives ou de protection ou lorsque la résistance aux taches est un facteur important. La méthode 2 s'applique aux couches anodiques utilisées à des fins architecturales en extérieur. Pour des applications moins critiques, la méthode 1 peut se révéler plus adaptée. Les méthodes ne sont pas applicables: - aux couches anodiques dures qui, normalement, ne sont pas colmatées; - aux couches anodiques qui ont été colmatées uniquement en solutions bichromatées; - aux couches anodiques produites dans des solutions d'acide chromique; - aux couches anodiques qui ont subi un traitement d'imperméabilisation. NOTE 1 Les méthodes évaluent la qualité du colmatage hydrothermique appliqué à l'aluminium anodisé. Elles peuvent être appropriées pour d'autres méthodes de colmatage. NOTE 2 Les méthodes sont destructives et peuvent servir de méthodes de référence en cas de doute ou de contestation sur les résultats des essais de perte de pouvoir absorbant (voir l'ISO 2143) ou de mesurage de l'admittance (voir l'ISO 2931).
General Information
Relations
Standards Content (Sample)
International
Standard
Fifth edition
Anodizing of aluminium and its
alloys — Assessment of quality of
sealed anodic oxidation coatings
by measurement of the loss of mass
after immersion in acid solution(s)
Anodisation de l'aluminium et de ses alliages — Évaluation de
la qualité des couches anodiques colmatées par mesurage de la
perte de masse après immersion en solution(s) acide(s)
PROOF/ÉPREUVE
Reference number
© ISO 2025
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
PROOF/ÉPREUVE
ii
Contents Page
Foreword .iv
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
5.1 General .2
5.2 Predip solution, used only for Method 2 .2
5.3 Test solution .2
5.3.1 Test solution A .2
5.3.2 Test solution B .2
6 Apparatus . 2
7 Preparation of test specimen . 2
8 Procedure . 3
8.1 Test solutions .3
8.2 Method 1 .3
8.3 Method 2 .4
9 Expression of results . 5
10 Test report . 5
Annex A (normative) Method for the degreasing and drying of test specimens . 6
Bibliography . 7
PROOF/ÉPREUVE
iii
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee
has been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO had not received notice of (a)
patent(s) which may be required to implement this document. However, implementers are cautioned that
this may not represent the latest information, which may be obtained from the patent database available at
www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 79, Light metals and their alloys, Subcommittee
SC 2, Organic and anodic oxidation coatings on aluminium, in collaboration with the European Committee for
Standardization (CEN) Technical Committee CEN/TC 132, Aluminium and aluminium alloys, in accordance
with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fifth edition cancels and replaces the fourth edition (ISO 3210:2017), which has been technically
revised.
The main changes are as follows:
— the maximum limit for the dissolved anodic oxidation coating and aluminium content in the test solutions
A and B has been reduced;
— the content of dissolved aluminium oxidation coating and aluminium in the used test solution has been
added to the test report in Clause 10.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
PROOF/ÉPREUVE
iv
International Standard ISO 3210:2025(en)
Anodizing of aluminium and its alloys — Assessment of
quality of sealed anodic oxidation coatings by measurement
of the loss of mass after immersion in acid solution(s)
1 Scope
This document specifies two methods to assess the quality of sealed anodic oxidation coatings on aluminium
and its alloys:
— Method 1 which assesses the quality of sealed anodic oxidation coatings by measuring the loss of mass
after immersion in a phosphoric acid based solution without prior acid treatment;
— Method 2 which assesses the quality of sealed anodic oxidation coatings by measuring the loss of mass
after immersion in a phosphoric acid based solution with prior acid treatment.
Method 1 is applicable to anodic oxidation coatings intended for decorative or protective purposes or where
resistance to staining is important.
Method 2 is applicable to anodic oxidation coatings intended for outdoor architectural purposes. For less
severe applications, Method 1 can be more suitable.
The methods are not applicable to the following:
— hard-type anodic oxidation coatings which normally are not sealed;
— anodic oxidation coatings that have been sealed only in dichromate solutions;
— anodic oxidation coatings produced in chromic acid solutions;
— anodic oxidation coatings that have undergone treatment to render them hydrophobic.
NOTE 1 While the methods assess the quality of hydrothermal sealing applied to anodized aluminium, they can be
appropriate for other sealing methods.
NOTE 2 The methods are destructive and can serve as reference methods in case of doubt or dispute regarding the
results of the test for loss of absorptive power (see ISO 2143) or the measurement of admittance (see ISO 2931).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 7583, Anodizing of aluminium and its alloys — Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7583 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at http:// www .iso .org/ obp
— IEC Electropedia: available at https:// www .electropedia .org/
PROOF/ÉPREUVE
4 Principle
An unsealed anodic oxidation coating on aluminium is dissolved rapidly by acid media, whereas a well-
sealed coating can withstand long immersion without appreciable attack.
The methods are surface specific. They test the resistance of the surface of a sealed anodic oxidation coating
to attack by certain acid solutions. They do not test quality through the whole thickness of the coating.
5 Reagents
5.1 General
Use only reagents of recognized analytical grade and distilled water or deionized water.
5.2 Predip solution, used only for Method 2
This is an aqueous solution containing (470 ± 15) g/l of nitric acid.
NOTE This solution can be obtained, for example, by diluting a 65 % nitric acid solution (ρ = 1,40 g/ml) with an
equal volume of water.
5.3 Test solution
5.3.1 Test solution A
This is an aqueous solution containing, per litre, 35 ml of phosphoric acid (ρ = 1,7 g/ml) and 20 g of
chromium(VI) oxide.
WARNING — The test solution A contains chromium (VI) and the user of this document should use
the test solution B when it is possible.
5.3.2 Test solution B
This is an aqueous solution containing, per litre, 35 ml of phosphoric acid (ρ = 1,7 g/ml).
6 Apparatus
Usual laboratory apparatus and glassware together with a laboratory balance with a readability of 0,1 mg.
7 Preparation of test specimen
Cut a piece from the material to be tested. Avoid contact areas such that there is an area of approximately 1 dm ,
but not less than 0,5 dm , of significant surface area. The mass of the test specimen should not exceed 200 g.
For hollow extrusions, take the test specimen from the end of the sections where the total (external
plus internal) surface area has an anodic oxidation coating (due to the throwing power of the anodizing
electrolyte).
In special cases (e.g. certain types of jigging, small hollow sections), it is necessary to remove the anodic
oxidation coating from the inside surface and to carry out the test on the coating on the outer surface of
the extrusion. If test solution A is used, the anodic oxidation coating may be removed from the inside by
mechanical abrasion or by chemical dissolution. Otherwise, the inside surface may be masked.
If by agreement between the anodizer and the customer, special test specimens are prepared, they shall be
of the same alloy as the production components and processed through the anodizing line at the same time
as the production components.
PROOF/ÉPREUVE
8 Procedure
8.1 Test solutions
Test solution A does not attack bare metal. It is not necessary to take uncoated surfaces into account.
Test solution B attacks bare metal to a limited extent. However, it is not necessary to take uncoated surfaces
into account if conditions a) and b) are both satisfied:
a) Dissolution of an uncoated specimen of the metal does not exceed 10 mg/dm over the operations in
8.2.4 to 8.2.6 or 8.3.4 to 8.3.8 depen
...
2025-03-05
ISO/FDISPRF 3210:2025(en)
ISO/TC 79/SC 2/WG 15
Secretariat: JISC
Date: 2025-08-12
Anodizing of aluminium and its alloys — Assessment of quality of
sealed anodic oxidation coatings by measurement of the loss of mass
after immersion in acid solution(s)
Anodisation de l'aluminium et de ses alliages — Évaluation de la qualité des couches anodiques colmatées par
mesurage de la perte de masse après immersion en solution(s) acide(s)
PROOF
ISO/PRF 3210:2025(en)
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this
publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including
photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested
from either ISO at the address below or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: + 41 22 749 01 11
Fax: +41 22 749 09 47
EmailE-mail: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
ISO/PRF 3210:2025(en)
iii
ISO/PRF 3210:2025(en)
Contents Page
Foreword . v
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Principle . 2
5 Reagents . 2
5.1 General. 2
5.2 Predip solution, used only for Method 2 . 2
5.3 Test solution . 2
6 Apparatus . 2
7 Preparation of test specimen . 2
8 Procedure . 3
8.1 Test solutions . 3
8.2 Method 1 . 3
8.3 Method 2 . 4
9 Expression of results . 5
10 Test report . 5
Annex A (normative) Method for the degreasing and drying of test specimens . 7
Bibliography . 8
iv
ISO/PRF 3210:2025(en)
Foreword
ISO (the International Organization for Standardization) is a worldwide federation of national standards
bodies (ISO member bodies). The work of preparing International Standards is normally carried out through
ISO technical committees. Each member body interested in a subject for which a technical committee has
been established has the right to be represented on that committee. International organizations,
governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely
with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.
The procedures used to develop this document and those intended for its further maintenance are described
in the ISO/IEC Directives, Part 1. In particular, the different approval criteria needed for the different types
of ISO document should be noted. This document was drafted in accordance with the editorial rules of the
ISO/IEC Directives, Part 2 (see www.iso.org/directives).
ISO draws attention to the possibility that the implementation of this document may involve the use of (a)
patent(s). ISO takes no position concerning the evidence, validity or applicability of any claimed patent
rights in respect thereof. As of the date of publication of this document, ISO [had/had not] received notice of
(a) patent(s) which may be required to implement this document. However, implementers are cautioned
that this may not represent the latest information, which may be obtained from the patent database
available at www.iso.org/patents. ISO shall not be held responsible for identifying any or all such patent
rights.
Any trade name used in this document is information given for the convenience of users and does not
constitute an endorsement.
For an explanation of the voluntary nature of standards, the meaning of ISO specific terms and expressions
related to conformity assessment, as well as information about ISO's adherence to the World Trade
Organization (WTO) principles in the Technical Barriers to Trade (TBT), see
www.iso.org/iso/foreword.html.
This document was prepared by Technical Committee ISO/TC 79, Light metals and their alloys,
Subcommittee SC 2, Organic and anodic oxidation coatings on aluminium, in collaboration with the European
Committee for Standardization (CEN) Technical Committee CEN/TC 132, Aluminium and aluminium alloys, in
accordance with the Agreement on technical cooperation between ISO and CEN (Vienna Agreement).
This fifth edition cancels and replaces the fourth edition (ISO 3210:2017), which has been technically
revised.
The main changes are as follows:
— — the maximum limit for the dissolved anodic oxidation coating and aluminium content in the
test solutions A and B has been reduced;
— — the content of dissolved aluminium oxidation coating and aluminium in the used test solution
has been added to the test report in 10(Clause 10).
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www.iso.org/members.html.
v
ISO/PRF 3210:2025(en)
Anodizing of aluminium and its alloys — Assessment of quality of
sealed anodic oxidation coatings by measurement of the loss of mass
after immersion in acid solution(s)
1 Scope
This document specifies two methods of assessingto assess the quality of sealed anodic oxidation coatings on
aluminium and its alloys by measurement of the loss of mass after immersion in acid solution(s).:
It consists of the following two methods:
— — Method 1: Assessment of which assesses the quality of sealed anodic oxidation coatings by
measurement ofmeasuring the loss of mass after immersion in a phosphoric acid based solution without
prior acid treatment.;
— — Method 2: Assessment of which assesses the quality of sealed anodic oxidation coatings by
measurement ofmeasuring the loss of mass after immersion in a phosphoric acid based solution with
prior acid treatment.
Method 1 is applicable to anodic oxidation coatings intended for decorative or protective purposes or where
resistance to staining is important.
Method 2 is applicable to anodic oxidation coatings intended for outdoor architectural purposes. For less
severe applications, Method 1 can be more suitable.
The methods are not applicable to the following:
— — hard-type anodic oxidation coatings which normally are not sealed;
— — anodic oxidation coatings that have been sealed only in dichromate solutions;
— — anodic oxidation coatings produced in chromic acid solutions;
— — anodic oxidation coatings that have undergone treatment to render them hydrophobic.
NOTE 1 TheWhile the methods assess the quality of hydrothermal sealing applied to anodized aluminium. They,
they can be appropriate for other sealing methods.
NOTE 2 The methods are destructive and can serve as reference methods in case of doubt or dispute regarding the
results of the test for loss of absorptive power (see ISO 2143) or the measurement of admittance (see ISO 2931).
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.
ISO 7583, Anodizing of aluminium and its alloys — Terms and definitions
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 7583 apply.
ISO and IEC maintain terminology databases for use in standardization at the following addresses:
ISO/PRF 3210:2025(en)
— — ISO Online browsing platform: available at http://www.iso.org/obp
— — IEC Electropedia: available at https://www.electropedia.org/
4 Principle
An unsealed anodic oxidation coating on aluminium is dissolved rapidly by acid media, whereas a well-
sealed coating can withstand long immersion without appreciable attack.
The methods are surface specific. They test the resistance of the surface of a sealed anodic oxidation coating
to attack by certain acid solutions. They do not test quality through the whole thickness of the coating.
5 Reagents
5.1 General
Use only reagents of recognized analytical grade and distilled water or deionized water.
5.2 Predip solution, used only for Method 2
AqueousThis is an aqueous solution containing (470 ± 15) g/l of nitric acid.
NOTE This solution can be obtained, for example, by diluting a 65 % nitric acid solution (ρ = 1,40 g/ml) with an
equal volume of water.
5.3 Test solution
5.3.1 Test solution A
AqueousThis is an aqueous solution containing, per litre, 35 ml of phosphoric acid (ρ = 1,7 g/ml) and 20 g
of chromium(VI) oxide.
Warning -WARNING — The test solution A contains chromium (VI) and the user of the present
standardthis document should preferuse the test solution B when it is possible.
5.3.2 Test solution B
AqueousThis is an aqueous solution containing, per litre, 35 ml of phosphoric acid (ρ = 1,7 g/ml).
6 Apparatus
Usual laboratory apparatus and glassware together with a laboratory balance with a readability of 0,1 mg.
7 Preparation of test specimen
Cut a piece from the material to be tested. Avoid contact areas such that there is an area of approximately
2 2
1 dm , but not less than 0,5 dm , of significant surface area. The mass of the test specimen should not exceed
200 g.
For hollow extrusions, take the test specimen from the end of the sections where the total (external plus
internal) surface area has an anodic oxidation coating (due to the throwing power of the anodizing
electrolyte).
In special cases (e.g. certain types of jigging, small hollow sections), it is necessary to remove the anodic
oxidation coating from the inside surface and to carry out the test on the coating on the outer surface of the
ISO/PRF 3210:2025(en)
extrusion. If test solution A is used, the anodic oxidation coating may be removed from the inside by
mechanical abrasion or by chemical dissolution. Otherwise, the inside surface may be masked.
If by agreement between the anodizer and the customer, special test specimens are prepared, they shall be
of the same alloy as the production components and processed through the anodizing line at the same time
as the production components.
8 Procedure
8.1 Test solutions
Test solution A does not attack bare metal. It is not necessary to take uncoated surfaces into account.
Test solution B attacks bare metal to a limited extent. However, it is not necessary to take uncoated surfaces
into account if conditions a) and b) are both satisfied:
a) a) Dissolution of an uncoated specimen of the metal does not exceed 10 mg/dm over the
operations 8.2.4in 8.2.4 to 8.2.68.2.6 or 8.3.48.3.4 to 8.3.88.3.8 depending on the method being used.
b) b) The uncoated surface area does not exceed 20 % of the total surface area if the uncoated
surface was created by cutting or mechanical abrasion to remove the anodic oxidation coating or by
chemical dissolution of the anodic oxidation coating.
Where either condition is not satisfied, the uncoated surface may be masked using an adherent material that
neither gains nor loses mass in excess of 1,0 mg/dm over the operations 8.2.4in 8.2.4 to 8.2.68.2.6 or
8.3.48.3.4 to 8.3.88.3.8 depending on the method being used.
The dissolution of an uncoated specimen of the metal may be determined by using an uncoated specimen of
the same alloy as that of the test specimen. Empirical data indicate that the dissolution of each of the alloys
AA 1050A, 1080A, 5005, 5005A, 5657, 5754, 6060, 6063 and 6063A satisfies condition a).
8.2 Method 1
8.2.1 8.2.1 Remove any sealing smut from the test specimen by rubbing with a dry cloth.
8.2.2 8.2.2 Measure the total coated surface area of the test specimen (excluding cut edges and other
uncoated surfaces).
8.2.3
...
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