EN ISO 10308:1997

SLOVENSKI STANDARD
01-oktober-1999
Kovinske prevleke - Pregled preskusov za ugotavljanje poroznosti (ISO
10308:1995)
Metallic coatings - Review of porosity tests (ISO 10308:1995)
Metallische Überzüge - Übersicht der Porenprüfverfahren (ISO 10308:1995)
Revetements métalliques - Passage en revue des essais de porosité (ISO 10308:1995)
Ta slovenski standard je istoveten z: EN ISO 10308:1997
ICS:
25.220.40 Kovinske prevleke Metallic coatings
2003-01.Slovenski inštitut za standardizacijo. Razmnoževanje celote ali delov tega standarda ni dovoljeno.

INTERNATIONAL Is0
STANDARD 10308
First edition
1995-l 2-l 5
Metallic coatings - Review of porosity
tests
Rev&ements mbtalliques - Passage en revue des essais de porosit6
Reference number
IS0 10308: 1995(E)
Contents
1 Scope . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
2 Normative references . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
3 Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
4 Principle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Common features of porosity tests . 2
Test specimens . 2
7 Specific porosity tests . 2
7.1 Alizarin test . 2
Anthraquinone test . 2
7.2
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
7.3 Cadmium sulfide test
........................................................... 3
7.4 Copper sulfate (Preece) test
...................................................... 3
7.5 Copper sulfate (Dupernell) test
................................................................. 3
7.6 Corrodkote test (CORR)
7.7 Electrographic tests .
7.8 Ferrocyanide test .
7.9 Ferron test .
7.10 Ferroxyl test . 4
....................................................... 4
7.11 Flowers of sulfur porosity test
7.12 Hot water test .
............. 5
7.13 Hydrogen sulfide or sulfur dioxide/hydrogen sulfide test.
7.14 Logwood test . 5
7.15 Magneson test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.16 Nitric acid vapour test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
7.17 Oxine test
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.18 Permanganate test
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.19 Polysulfide test
7.20 Porotest test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
0 IS0 1995
All rights reserved. Unless otherwise specified, no part of this publication may be
reproduced or utilized in any form or by any means, electronrc or mechanical, including
photocopying and microfilm, without permission in writing from the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
IS0 10308:1995(E)
@ IS0
7.21 Salt spray tests [neutral (NSS), acetic (AASS) and cuproacetic
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
(CAWI
. . . . . .-. 6
7.22 Sulfur dioxide test
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
7.23 Sulfurous acid/sulfur dioxide vapour test
7.24 Thiocyanate test . . . . . . . . . . . .-. 7
7.25 Thioacetamide test (TAA) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.26 Watch case acetic acid test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
7.27 Watch case sodium bisulfite test . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
Annexes
.................................................................... 8
A Table of porosity tests
............................... 10
B Typical report and evaluation of porosity tests
Bl . Report .
B2 . Evaluation .
B3 . Precision and bias .
C Schematic representation-of types of pore . 11
D Classification of discontinuities in metallic and other inorganic
coatings . 12
E Classification of methods of testing coating porosity . 13
F Alphabetical list of tests by substrate and coating. . 14
Bibliography . 22
G
. . .
III
IS0 10308:1995(E) @ IS0
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
collaborates closely with the International Electrotechnical Commission
(IEC) on all matters of electrotechnical standardization.
Draft International Standards adopted by the technical committees are
circulated to the member bodies for voting. Publication as an International
Standard requires approval by at least 75 % of the member bodies casting
a vote.
International Standard IS0 10308 was prepared by Technical Committee
ISO/TC 107, Metallic and other inorganic coatings, Subcommittee SC 7,
Corrosion tests.
Annex A forms an integral part of this International Standard. Annexes B to
G are for information only.
INTERNATIONAL STANDARD o iso IS0 10308:1995(E)
Metallic coatings - Review of porosity tests
2 Normative references
1 Scope
The following standards contain provisions which,
This International Standard reviews published
through references in this text, constitute provisions
methods for revealing pores (see IS0 2080) and
discontinuities in coatings of aluminium, anodized alu- of this International Standard. At the time of publi-
minium, brass, cadmium, chromium, cobalt, copper, cation, the editions indicated were valid. All standards
gold, indium, lead, nickel, nickel-boron, nickel-cobalt, are subject to revision, and parties to agreements
nickel-iron, nickel-phosphorus, palladium, platinum, based on this International Standard are encouraged
vitreous or porcelain enamel, rhodium, silver, tin, tin- to investigate the possibility of applying the most
lead, tin-nickel, tin-zinc, zinc and chromate or recent editions of the standards listed below. Mem-
phosphate conversion coatings (including associated bers of IEC and IS0 maintain registers of currently
organic films) on aluminium, beryllium-copper, brass, valid International Standards.
copper, iron, kovar (NiFeCo) alloys, magnesium,
nickel, nickel-boron, nickel-phosphorus, phosphor-
IS0 1456: 1988, Metallic coatings - flectrodeposited
bronze, silver, steel, tin-nickel and zinc alloy base coatings of nickel plus chromium and of copper plus
metal. nickel plus chromium.
The tests summarized in this International Standard
IS0 2080: 1981, f lectroplating and related pro-
are designed to react with the substrate when
cesses - Vocabulary.
exposed, by a discontinuity, in such a way as to form
an observable reaction product.
IS0 2085:1976, Anodizing of aluminium and its
alloys - Check of continuity of thin anodic oxide
coatings - Copper sulpha te test.
NOTES
IS0 3160-2:1992, Watch cases and accessories -
1 Pores are usually perpendicular to the coating surface
but may be inclined to the coating surface. They are Gold alloy coverings - Part 2: Determination of fine-
frequently cylindrical in shape but may also assume a
ness, thickness, corrosion resistance and adhesion.
twisted shape (see annex C).
2 Porosity may vary in size from the submicroscopic, IS0 4524-2:1985, Metallic coatings - Test methods
invisible under a light microscope, to the microscopic,
for electrodeposited gold and gold alloy coatings -
visible from x 10 to x 1 000, to the macroscopic, visible to
Part 2: f nvironmen tal tests.
the naked eye.
IS0 4524-3:1985, Metallic coatings - Test methods
3 Porosity may be visibly indicated by discoloration of the
coated surface. for electrodeposited gold and gold alloy coatings -
Part 3: f lectrographic tests for porosity.
4 Porosity in a coating is not always detrimental. In
microdiscontinuous chromium, for example, porosity or
IS0 4525:1985, Metallic coatings - Electroplated
microcracking is required and tests are conducted to
indicate the pores. coatings of nickel plus chromium on plastics materials.
5 Results obtained from porosity tests expressed in terms
IS0 4526: 1984, Metallic coatings - Electroplated
such as pores per square centimetre are relative values
coatings of nickel for engineering purposes.
related to the specific test method used and the
magnification used during examination. Annex B gives
typical report criteria.
IS0 10308:1995(E) @ IS0
IS0 4527: 1987, Autocatalytic nickel-phosphorus coat- primarily short-time tests. A good porosity test
depolarize and activate the
ings - Specification and test methods. process must clean,
substrate metal exposed by the pore and attack it to
such a degree as to cause the reaction product to fill
IS0 4538: 1978, Metallic coatings - Thioacetamide
corrosion test (TAA test). the pore to the surface of the coating. Ideally, the
corrosive provided for this should not react with the
IS0 4540:1980, Metallic coatings - Coatings cathodic coating surface. It is essential that the time of reaction
to the substrate - Ratings of electroplated test be limited, particularly with thin coatings, since the
specimens subjected to corrosion tests. corrosive will attack the substrate in all directions and
in so doing, will undermine the coatings such that
IS0 4541 :I 978, Metallic and other non-organic coat- false observations will be made. When the corrosion
ings - product is soluble in the reagent, the precipitating
Corrodko te corrosion test (CO R R test).
indicator is used to form the reaction product. (See
annex E for classification of methods of porosity
IS0 6158: 1984, Metallic coatings - f lectroplated
testing.)
coatings of chromium for engineering purposes.
IS0 6988: 1985, Metallic and other non-organic coat-
ings - Sulfur dioxide test with general condensation
of moisture.
6 Test specimens
Porosity tests are generally destructive in nature and
IS0 9227:1990, Corrosion tests in artificial atmos-
are designed to assess the quality of the coating
pheres - Salt spray tests.
process of the substrate. Therefore, separate test
specimens are not ordinarily allowed.
IS0 10309:1994, Metallic coatings - Porosity tests -
Ferroxyl test.
7 Specific porosity tests
3 Definitions
7.1 Alizarin test
For the purposes of this International Standard, the
7.1.1 Scope
definitions given in IS0 2080 as well as the following
apply*
For coatings of chromium (including Cr/Ni/Cu and
Cr/Ni/Ni), cobalt, copper, nickel, nickel-boron, nickel-
cobalt, nickel-iron and nickel-phosphorus on aluminium
3.1 discontinuities: Cracks, micro-holes, pits,
substrate.
scratches or any other opening in the coating surface
that exposes a different underlying metal.
7.1.2 Summary of method
For further information on discontinuities see annex D
The test specimens are treated with sodium
and reference [I] in annex G.
hydroxide, sodium alizarin sulfonate and glacial acetic
acid under defined conditions. Formation of red
markings or spots indicates porosity. Details of the
test procedure can be found in IS0 4527. See also
4 Principle
references [9, 31 and 371 in annex G.
Porosity test results occur as chemical reaction end-
products. Some occur in situ, others on paper or in a
7.2 Anthraquinone test
gel coating. Observations are made that are consist-
ent with the test method and the items being tested
7.2.1 Scope
as specified by the buyer. These may be visual
inspections (naked eye) or at x 10 magnification
For coatings of chromium (including Cr/Ni/Ni), cobalt,
(microscope). Other methods may involve enlarged
nickel, nickel-boron, nickel-cobalt, nickel-iron and
photographs or photo-micrographs. See references [ 1,
nickel-phosphorus on aluminium, magnesium or zinc
2, 3, 5 and 61 in annex G (see also annex A for a tabu-
alloy substrates.
lar summary of the porosity tests and annex D for a
classification of discontinuities).
7.2.2 Summary of method
The test specimens are treated with sodium
hydroxide and potassium 1 -aminoanthraquinone-2-
5 Common features of porosity tests
carboxylic acid under defined conditions. Formation of
red markings or spots indicates porosity. Details of
the test procedure can be found in reference 1131 in
Porosity tests differ from corrosion and ageing tests
particularly concerning testing time. Porosity tests are annex G.

@ IS0 IS0 10308:1995(E)
7.3 Cadmium sulfide test 7.6.2 Summary of method
The test specimen is coated with a slurry of corrosive
7.3.1 Scope
salts and dried. The coated specimens are then
For metallic coatings of chromium (including Cr/Ni/Ni),
exposed to high relative humidity for a specified
gold, palladium, platinum and rhodium on beryllium-
period of time. Details of the test procedure can be
copper, brass, copper, phosphor-bronze and silver
found in IS0 4541. See also references [26 and 511 in
substrates.
annex G.
7.3.2 Summary of method
7.7 Electrographic tests
Filter paper is soaked in cadmium chloride and then
treated with sodium sulfide to precipitate cadmium
7.7.1 Scope
sulfide. Details of the test procedure can be found in
Variation A. Acrylamide electrography (See warning
IS0 4524-3.
in 7.7.2.)
For gold coatings on nickel and silver, or nickel coat-
7.4 Copper sulfate (Preece) test
ings on copper substrates.
7.4.1 Scope
Variation B. Gel bulk electrography.
Variation A. For coatings of cadmium and zinc on
iron, steel or iron-based alloy substrates. For gold, cobalt, nickel and palladium coatings on cop-
per; gold, copper, cobalt and palladium coatings on
Variation B. For thin (< 5 pm) anodic oxide coatings nickel; gold on silver substrates.
on aluminium alloy substrates.
Variation C. Paper electrography.
7.4.2 Summary of method
For the following combinations of indicator-coatings/
substrate that have flat or nearly flat surfaces.
The test specimen is immersed in a solution of copper
sulfate; different solution compositions are used for
aluminium alloy and iron alloy substrates. Reddish Indicator Coating/substrate
markings or spots, of copper, indicate pores on fer-
1. Cadmium sulfide Chromium, gold, palladium,
rous substrates; black markings or spots indicate
platinum and rhodium on
pores on aluminium alloy substrates. Details of the
beryllium-copper, brass,
test procedures can be found in reference [38] in
copper, phosphor-bronze
annex G and also in IS0 2085.
and silver substrates
2. Dimethylglyoxime Gold, palladium, platinum,
rhodium and silver on brass,
7.5 Copper sulfate (Dupernell) test
beryllium-copper, copper,
7.5.1 Scope
phosphor-bronze, nickel,
nickel-boron and nickel-
For coatings of chromium and micro-cracked or micro-
phosphorus substrates
porous chromium on nickel/copper or nickel/nickel on
3. Dithiooxamide Chromium, gold, palladium,
aluminium, iron, steel or zinc alloy substrates.
platinum and rhodium on
beryllium-copper, brass,
7.5.2 Summary of method
copper and phosphor-bronze
substrates
The test specimen is made the cathode in an acid
copper plating bath. Copper is deposited only where
4. Nioxime
Gold, palladium, platinum
the base metal or undercoat is exposed, the chro-
and rhodium on nickel,
mium remaining passive. Details of the test procedure
nickel-boron, nickel-iron,
can be found in IS0 1456, IS0 4525 and IS0 6158.
nickel-phosphorus and tin-
See also references [40 and 411 in annex G.
nickel substrates
5. Potassium Chromium, gold, palladium,
Ferrocyanide platinum and rhodium on
7.6 Corrodkote test (CORR)
brass, beryllium-copper,
copper and phosphor-bronze
7.6.1 Scope
substrates
For coatings of chromium and micro-cracked or micro-
6. Potassium Cadmium, nickel, tin and
porous chromium on nickel/copper or nickel/nickel on
Ferricyanide zinc on brass, silver and
aluminium alloy, plastic, steel and iron alloy or zinc
steel substrates
alloy substrates.
IS0 10308:1995(E) @ IS0
7. Magneson Chromium, cobalt, copper, porosity. Details of the test procedure can be found in
nickel, nickel-boron, nickel- IS0 4527. See also references [I2 and 371 in annex G.
cobalt, nickel-iron and nickel-
phosphorus on magnesium
substrates
7.9 Ferron test
7.9.1 Scope
7.72 Summary of methods
For coatings of aluminium, brass, cadmium, chro-
mium, cobalt, indium, lead, nickel, nickel-boron, nickel-
Variation A. Acrylamide electrography.
phosphorus, porcelain enamel, organic films, silver,
Acrylamide solution containing a hardener and an indi-
tin, tin-lead, tin-nickel, tin-zinc and zinc, on iron and
cator is poured on to the sample shortly before
steel substrates.
gelatinizing. The sample is made the anode in a cell
with a chloride solution and electrolized. Pores are
7.9.2 Summary of method
revealed as coloured marks or spots. Details of the
test procedure can be found in reference [7] in an-
The test specimens are treated with acid and a 0,l %
nex G.
solution of ferron (8-hydroxyquinoline 7-iodo-5-sulfonic
acid), under defined conditions. Formation of red
WARNING - Acrylamide has been identified as a
markings or spots indicates porosity. Details of the
neurotoxin and carcinogen; use with extreme
test procedure can be found in reference [4] in an-
caution.
nex G.
Variation B. Gel bulk electrography.
7.10 Ferroxyl test
A mixture of clear gelatine, conducting salts and an
indicator are poured into an electrolytic cell with a gold
7.10.1 Scope
or platinum cathode and with the specimen as the
anode. The composite gel solution is allowed to
For metallic coatings such as brass, chromium, cobalt,
solidify following which the cell is electrolized. Pores
copper, gold, indium, lead, nickel, nickel-boron, nickel-
are revealed as coloured marks or spots. Details of
phosphorus, organic films, porcelain enamel, silver,
the test procedure can be found in reference [52] in
tin, tin-lead and tin-nickel that are resistant, for the
annex G.
duration of the test period, to ferricyanide and chloride
and are also cathodic to their iron-or steel alloy sub-
Variation C. Paper electrography.
strates.
Test specimens are sandwiched as an anode between
electrolyte-soaked paper and indicator paper and
7.10.2 Summary of method
clamped with two cathode covers (of non-reactive ma-
terials such as gold or stainless steel). A specified Electrolyte-wetted, gel-chloride-treated paper strips
are placed firmly in contact with test specimen sur-
current (usually 0,15 milliamps/cm* to I,55 milliamps/
faces for a specified time. After the allotted time, the
cm*) for a specified time (usually IO s to 30 s) is
paper strips are wetted adequately with ferricyanide
applied. After exposure, the test paper is wetted with
indicator and allowed to dry. indicator solution. Blue markings or spots indicate
pores. Details of the test procedure can be found in
A variety of commercially prepared test papers is
IS0 4526, IS0 4527 and IS0 10309. See also refer-
available. Details of the test procedures can be found
ences [29,35,36,39 and 431 in annex G.
in IS0 4524-3. See also references [I 5, 18, 35, 36 and
42linannexG.
7.11 Flowers of sulfur porosity test
7.11.1 Scope
7.8 Ferrocyanide test
Primarily for gold and nickel coatings on copper, cop-
per alloys or silver substrates. It may be used with
7.8.1 Scope
other coatings that do not significantly tarnish in
reduced sulfur atmospheres.
For coatings of chromium, cobalt, gold, nickel, nickel-
boron, nickel-iron, nickel-phosphorus, palladium, plati-
num and rhodium on copper substrate.
7.11.2 Summary of method
Test specimens are suspended on non-reactive sup-
7.8.2 Summary of method
ports in a non-reactive container with controlled
The test specimens are treated with glacial acetic acid humidity and elevated temperature (50 “C) for a speci-
and potassium ferrocyanide under defined conditions. fied time in a closed system over the flowers of
Formation of brown markings or spots indicates sulfur. Markings, spots or discoloration indicate
IS0 10308:1995(E)
@ IS0
porosity. Deta ils of the test procedure can be found in 7.14.2 Suinmary of method
reference [44] in annex G .
Paper strips treated with haematoxylin are immersed
in water and are placed firmly in contact with test
specimen surfaces for a specified time. After the
7.12 Hot water test
allotted time, the paper strips are examined for blue
7.12.1 Scope
markings or spots which indicate pores. Details of this
test can be found in references [8 and 1 I] in annex G.
For metallic coatings cathodic to a ferrous substrate;
for example, brass, copper, gold, indium, nickel,
nickel-boron, nickel-phosphorus, tin, tin-lead and tin-
7.15 Magneson test
nickel on iron, kovar (NiFeCo) alloys or steel sub-
strates; vitreous or porcelain enamel and organic films
7.15.1 Scope
on steel substrates.
For coatings of chromium, cobalt, copper, nickel,
7.12.2 Summary of method
nickel-boron, nickel-cobalt, nickel-iron and nickel-
phosphorus on magnesium substrates.
The test specimens are placed in a glass vessel filled
with neutral, aerated water at room temperature. Heat
is applied to the vessel at a rate that will bring the
7.15.2 Summary of method
water to a boil in 15 min to 20 min. Boiling is
The test specimens are treated with sodium hydrox-
continued for 30 min. After exposure and drying, black
ide. Dry magneson test paper, prepared by dipping
markings or spots and red rust indicate porosity.
filter paper in a 0,Ol % alcohol solution of p-nitro-
Details of the test procedure can be found in
benzene-azo-resorcinol is applied to the treated sur-
IS0 4527. See also references [37 and 431 in annex G.
face. Formation of blue markings or spots on a red
background indicates porosity. Details of the test pro-
cedure can be found in reference [I 51 in annex G.
7.13 Hydrogen sulfide or sulfur
dioxide/hydrogen sulfide test
7.13.1 Scope
7.16 Nitric acid vapour test
Variation A. For coatings of less than 5 pm of gold,
7.16.1 Scope
palladium or rhodium on beryllium-copper, brass, cop-
per, phosphor-bronze and silver substrates.
For gold coatings on beryllium-copper, brass, copper,
nickel, nickel-boron, nickel-phosphorus, phosphor-
Variation B. For coatings of more than 5 pm of gold,
bronze and tin-nickel substrates.
palladium, rhodium, tin, tin-lead, or tin-nickel on beryl-
lium-copper, brass, copper, nickel, nickel-boron, nickel-
phosphorus, phosphor-bronze or silver substrates.
7.16.2 Summary of method
A stabilized acid atmosphere is established by placing
7.13.2 Summary of method
concentrated nitric acid in a non-reactive container,
Variation A. Test specimens are suspended on non-
which is covered and left to stand for 0,5 h at a
reactive supports in a non-reactive container with a
specified ambience.
freshly generated hydrogen sulfide atmosphere for a
specified time, usually 24 h. Discoloration on the sur-
Test specimens are suspended in this closed system
face indicates porosity. Details of the test procedure atmosphere and exposed for a specified exposure
can be found in reference [27] in annex G. time; 1 h for copper alloy substrates and 2 h for nickel-
based substrates. After exposure the specimens are
Variation B. Test specimens are suspended on non-
baked to dry and fix the reaction products. Each
reactive supports in a non-reactive container with a
reaction product marking or spot, usually protruding,
freshly generated sulfur dioxide atmosphere for a
indicates a pore in the coating. Details of the test pro-
specified time, usually 24 h. Followed by freshly
cedure can be found in IS0 4524-2. See also refer-
generated hydrogen sulfide atmosphere for a speci-
ence [45] in annex G.
fied time, usually 24 h. Discoloration on the surface
indicates porosity. Details of the test procedure can
be found in reference [I71 in annex G.
7.17 Oxine test
7.17.1 Scope
7.14 Logwood test
For coatings of chromium, cobalt, copper, nickel,
7.14.1 Scope
nickel-boron, nickel-cobalt, nickel-iron and nickel-
phosphorus on aluminium, magnesium and zinc sub-
For coatings of brass on aluminium; or silver on brass
strates.
and copper substrates.
IS0 10308:1995(E) @ IS0
7.17.2 Summary of method 7.21 Salt spray tests [neutral (NSS), acetic
(AASS) and cuproacetic (CASS)]
The test specimens are treated with sodium hydrox-
ide. Dry oxine test paper, prepared by dipping filter
7.21.1 Scope
paper in a 5 % alcohol solution of 8-hydroxyquinoline
is applied to the treated surface. Formation of For metallic coatings such as brass, chromium, cobalt,
coloured markings or spots indicates porosity. Details copper, gold, lead, nickel, nickel-boron, nickel-
of the test procedure can be found in references [IO phosphorus, tin, tin-lead and tin-nickel that are resist-
ant, for the duration of the test period, to chloride and
and 141 in annex G.
which are also cathodic to their iron, steel, or iron-
based alloy substrates. The test is also suitable for
coatings of chromium on nickel/copper and chromium
on nickel/nickel on aluminium, magnesium and zinc
7.18 Permanganate test
substrates.
7.18.1 Scope
7.21.2 Summary of method
For coatings of aluminium, cadmium and zinc on iron,
steel or iron-based alloy substrates. Specimens are placed in a cabinet and subjected to a
fog spray of 5 % sodium chloride solutions. Porosity is
indicated by black markings or spots and red rust on
7.18.2 Summary of method
substrates of iron, steel or iron-based alloys, or white
markings on spots, or blisters in the coating on sub-
The test specimen is immersed in a dilute solution of
strates of aluminium, magnesium or zinc alloy (see
potassium permanganate. Black markings or spots, of
IS0 4540). Details of the test procedure can be found
manganese dioxide, indicate pores. Details of this test
in IS0 9227. See also references [32, 33, 47 and 481 in
can be found in reference [8] in annex G.
annex G.
7.19 Polysulfide test
7.22 Sulfur dioxide test
7.19.1 Scope
7.22.1 Scope
For metallic coatings of tin, tin-nickel and tin-zinc on
Variation A. For coatings of gold on copper, copper
beryllium-copper , brass, copper and phosphor-bronze
alloys and nickel substrates.
substrates.
Variation B. For coatings of gold on silver substrates.
7.19.2 Summary of method
Variation C. For coatings of tin, tin-lead and tin-nickel
Coated parts are solvent-cleaned and then immersed
on copper, copper alloy and steel substrates.
in a solution of sodium polysulfide. Formation of black
marks or spots indicates pores. Details of the test
7.22.2 Summary of method
procedure can be found in reference [46] in annex G.
Test specimens are suspended on non-reactive sup-
ports in a non-reactive container with a freshly
generated sulfur dioxide atmosphere for a specified
7.20 Porotest test
time, usually 24 h. The concentrations of sulfur
dioxide, generated as the corrosive atmosphere, are
7.20.1 Scope
selected for the specific variation A, B or C (coating
and substrate combination). Colour on the surface
For metallic coatings such as brass, chromium, cop-
indicates porosity. Details of the test procedure can
per, gold, nickel, nickel-boron, nickel-phosphorus, tin,
be found in IS0 4524-2 and IS0 6988. See also refer-
tin-nickel and their alloys which are cathodic to their
ences [28,32,35,49 and 501 in annex G.
iron, steel or iron-based alloy substrates.
7.20.2 Summary of method
7.23 Sulfurous acid/sulfur dioxide vapour
Paper strips, treated with cr-nitroso-bnaphthol, are im-
test
mersed in water - or, to speed up the reaction, 5 %
- are placed firmly in contact with
sodium chloride
7.23.1 Scope
test specimen surfaces for a specified time. After the
For coatings of gold and palladium on beryllium-
allotted time, the paper strips are examined for green
copper, brass, copper, nickel, nickel-boron, nickel-
markings or spots which indicate pores. Details of this
phosphorus and phosphor-bronze substrates.
test can be found in reference [8] in annex G.
IS0 10308:1995(E)
@ IS0
7.23.2 Summary of method 7.25.2 Summary of method
Test specimens are suspended on non-reactive Test specimens are suspended on non-reactive
supports in a non-reactive container with a sulfurous supports in a non-reactive container with a saturated
acid/sulfur dioxide atmosphere for a specified time, solution of sodium acetate, for controlling humidity
usually 24 h. Colour on the surface indicates porosity. (75 % RH), and crystals of thioacetamide at 25 OC for
Details of the test procedure can be found in a specified time in the closed system. Markings, spots
reference [53] in annex G. or discoloration indicate porosity. Details of the test
procedure can be found in IS0 4538. See also
reference [I61 in annex G.
7.24 Thiocyanate test
7.26 Watch case acetic acid test
7.24.1 Scope
7.26.1 Scope
For metallic coatings such as chromium, copper,
nickel, nickel-boron, nickel-phosphorus, tin, tin-nickel
For gold coatings on cuprous alloy with or without
and their alloys that are resistant to thiocyanate and
nickel, and die-cast zinc-based alloy substrates.
chloride during the time period of the test and which
are also cathodic to their iron or steel alloy substrates.
7.26.2 Summary of method
7.24.2 Summary of method
Test specimens are suspended on non-reactive
supports in a non-reactive vessel and exposed to
Electrolyte-wetted, gel-chloride-treated paper strips
vapours of acetic acid for 24 h at 23 “C + 2 “C. Details
are placed firmly in contact with test specimen
of the test procedure can be found in IS0 3160-2.
surfaces for a specified time. After the allotted time,
the paper strips are wetted adequately with
thiocyanate indicator solution. Red markings or spots
7.27 Watch case sodium bisulfite test
indicate pores. Details of this test procedure can be
found in reference [8] in annex G.
7.27.1 Scope
For gold coatings on ferrous alloy substrates.
7.25 Thioacetamide test (TAA)
7.27.2 Summary of method
7.25.1 Scope
Test specimens are suspended on non-reactive
For gold, nickel or tin coatings on copper, copper supports in a non-reactive vessel and exposed to
alloys and silver substrates. This test can also be used vapours of sodium bisulfite for 24 h at 23 “C & 2 OC.
for organic coatings on brass, copper or silver Details of the test procedure can be found in
substrates. IS0 3160-2.
IS0 10308:1995(E)
Annex A
(normative)
Table of porosity tests
Substrate or underlayer
Copper alloys Iron alloys
Coating
Aluminium
alloys
Beryllium
Phosphor- Cast iron and
Brass Copper
Kovar
copper
bronze steel
Aluminium -
9, 18
Anodized aluminium 48 - - - - - -
14 - - - -
Brass
9, 10, 12, 20, 21 9, 10, 12
Cadmium 7C6
4A, 7C6, 9, 18 4A, 9
Chromate conversion 21 11
Chromium 1, 2, 5, 6, 17 3, 7c1, 7c3, 3, 7Cl) 7c3, 3, 7Cl) 7c3, 7c5,
3, 7c1, 7c3, 5, 6, 9, 10, 12, 20, 5,6, 9, 10,
7c5 7c5 8 7c5 21,24 12
1, 2, 56, 17, 3,7c5 3,7c5 3,7c5
Chromium on nickel/nickel 3,7c5 5, 6, 9, 10, 20, 21 5, 6, 9, 10
1, 2, 5, 6, 17, 3,7c5 3,7c5 3,7c5
Chromium on nickel/copper 3,7c5 5, 6, 9, 10, 20, 21 5, 6, 9, 10
Cobalt 1, 2, 17 8, 7B 9, 10, 12
9, 10, 12, 21
Copper 1, 17 - - - - 10, 12, 20, 21, 24 10,12
Gold 3, 7C1, 7C2, 3, 7C1, 7C2, 7B, 7C1, 7C2,
3, 3, 7C1, 7C2, 10, 12, 20, 21, 27 10,12
7c3, 7c5, 11, 7c3, 7c5, 11, 7C3, 7C5, 8, 11, 7c3, 7c5, 11,
13A, 138, 16, 13A, 13B, 16, 13A, 13B, 16, 22A, 13A, 13B, 16,
22A, 23, 25,26 22A, 23, 25,26 23,24, 25, 26 22A, 23, 25, 26
lndium
9, 10, 12 9, 10, 12
Lead
9, 10, 12,21,22 9, 10, 12
Nickel 1,2, 17 11,25 7C6,11,25 7A, 7B,
11,25 1, 7C6, 9, 10, 12, 9, 10, 12
1, 10, 11,
25 20, 21, 24
11,25 11,25 8, 25
Nickel-boron 1, 2, 17 11, 11,25 9, 10, 12, 20, 21, 9, 10, 12
11 11
Nickel-cobalt 1, 2, 17 11 11
1, 2, 17 11 11 11 11
Nickel-iron
9, 10, 12, 20, 21, 9, 10, 12
Nickel-phosphorus 1, 2, 17 11,25 11,25 8, 11, 25 11,25
Palladium 3, 7C1, 7C2, 3, 7A, 7C1, 3, 76, 7C1, 7C2, 3, 7C1, 7C2,
7C3,7C5, 13A, 7C2, 7C3, 7C5,
7C3, 7C5, 8, 13A, 7C3,7C5,13A,
13B, 23 13A, 13B, 23 13B, 23 13B, 23
Phosphate conversion
Platinum 3, 7C1, 7C2, 3, 7C1, 7C2, 3, 7C1, 7C2, 7C3,
3, 7C1, 7C2,
7c3,7c5 7c3,7c5 7c5
7c3,7c5
Rhodium 3, 7C1, 7C2, 3, 7C1, 7C2, 3, 7C1, 7C2, 7C3, 3, 7C1, 7C2,
7C3, 7C5, 13A, 7C3, 7C5, 13A, 7C5,8,13A, 13B 7C3, 7C5, 13A,
13B 13B 13B
Silver 7C2 7C2,14 7C2,14
7C2 9, 10 9, 10
Tin 19,22C, 25 7C6, 19, 22C, 13B, 19,22C, 7C6, 9, 10, 12, 20, 9, 10, 12
25 19,22C, 25
25 21,22C, 24
22c 13B, 22C
Tin-lead 22c 22c 9, 10, 12, 21, 22c 9, 10, 12
Tin-nickel 19,22C, 25 19,22C, 25 13B, 19,22C, 25
19,22C, 25 9, 10, 12, 20, 21, 9, 10, 12
22C, 24
Tin-zinc 19 19 19
19 9 9
Zinc 7C6
4A, 7C6, 9, 18 4A, 9
Vitreous and porcelain
9, 10, 12 9, 10, 12
enamel
11,25 11,25 11,25 9, 10, 12 9, 10, 12
Organic films 4 11,25
NOTE - Numbers refer to subclauses of clause 7, and the letters to their vartations.
ISO10308:1995(E)
Substrate or underlayer
Coating
Nickel alloys
Magnesium Silver Tin-nickel
Zinc alloys
alloys
Nickel Nickel-boron Nickel-phosphorus
Aluminium
- - - -
- - -
Anodized aluminium
Brass
Cadmium 7C6
Chromate conversion 21 21
2, 7c7, 15, 5
Chromium 3,7Cl 2, 5,6, 17,
17,21 21
Chromium on nickel/nickel 2, 7c7, 15,
2, 5, 6, 17,
17,21 21
Chromium on nickel/copper 2, 7c7, 15,
2, 5,6, 17,
17,21 21
Cobalt 2, 7c7, 15, 2, 17, 21
17,21
Copper 7c7,15,17 7B 17
Gold 1, 7A, 7B, 7C2, 7C2, 7C4, 7C2,7C4,16,23 7C4,16,23 26
16, 1,3,7A, 78,
7C4,13B, 16, 23 7C1, 11, 13A,
22A, 23 13B, 22B, 25
lndium
Lead
- -
Nickel 2, 7C7, 15, 17 -
2, 17, 21
7C6,11,25
- - -
Nickel-boron 2, 7c7, 15, 17
2, 17, 21
11,25
- - -
Nickel-cobalt 2, 7c7, 15, 17
2, 17, 21
- - -
Nickel-iron 2, 7c7, 15, 17
11 2, 17, 21
2, 17
11,25
2, 7c7, 15, 17
Nickel-phosphorus
Palladium 7B, 7C2, 7C4, 7C2, 7C4, 13B, 7C2,7C4, 13B, 23 3, 7C1, 13A, 7C4,23
13B
138,23 23
Phosphate conversion
Platinum 7C2,7C4 7C2,7C4 7C2,7C4 3,7Cl 7c4
Rhodium 7C2,7C4,13B 7C2,7C4,13B 7C2,7C4,13B 3, 7C1, 13A, 7c4
13B
-
Silver 7C2 7C2 7C2
Tin
7C6,13B, 25
Tin-lead
13B
13B, 25 -
Tin-nickel
Tin-zinc
-
Zinc 7C6
Vitreous and porcelain
enamel
Organic films
~ NOTE - Numbers refer to subclauses of clause 7, and the letters to their variations.
IS0 10308:1995(E)
Annex B
(informative)
Typical report and evaluation of porosity tests
B.2.2 Procedure
B.l Report
In option 1, count individual pores at x IO magnifi-
The results of a porosity test are usually given in
cation in the significant area of the coating, as defined
terms of one of the following.
by the specification or drawing of the product. In
option 2, compare results with panels shown in
IS0 4540 or those supplied as criteria by the buyer. In
B.l.l Option 1
option 3, scan for the largest defect.
The number and size of the pores in the significant
B.2.3 Criteria (pass-fail)
area. Convert to a pore density in number of defects
per 100 mm*.
Pass-fail criteria are properly part of the specification
requiring the porosity test. The reasons for this are
B.1.2 Option 2 that the sensitivity of the individual methods vary from
one another and with the different metal combinations
therefore precluding a single criterion. Further, the
The percentage of total area covered by the pores.
wide variety of products to which coatings are applied
has, in itself, significantly different acceptance criteria
B.1.3 Option 3
for porosity.
The area, in square millimetres, of the largest marking Listed below are examples of the criteria frequently
or spot on the significant surface. used to constitute failure:
- a pore count greater than 50/100 mm* or an area
greater than 1 %;
- a marking, spot or crack with a total area greater
B.2 Evaluation
than 2,5 mm*.
B.2.1 Scope
Porosity tests offer some indication as to the
B.3 Precision and bias
expected performance of coating(s) when exposed to
corrosive environments. When a given coating of a
Porosity tests serve to indicate the completeness of
specified thickness is known to be protective when
protection or cover offered by the coating. The effects
properly deposited, the porosity test(s) serve(s) as a
of substrate, process, handling and packaging, may all
measure of control of the process. When the coating
affect the degree of imperfection measured. For this
is porous, one or more of the following may be the
reason, these tests serve only as qualitative guides to
cause: substrate finish; substrate preparation; plating
keeping the coating, handling and packaging pro-
bath; coating process. cesses under control.

IS0 10308:1995(E)
Annex C
(informative)
Schematic representation of types of pore
Various types of pore are shown schematically in figure C.I. See also reference [8] in annex G.
Through pores
A B C D
Vertical Inclined Convoluted Branched
Masked pores
E F G
Sealed at surface Completely hidden Sealed at base
Pores or pits arising from defects in the base metal
I
H J
Base metal pores U-grooves V-grooves
Pits due to local shielding
K L
Pit due to oil fit due to suspended matter Hydrogen pit
Key
A to D: pores due to inherent coating properties
E to G: pores due to the masking effect
H to J: pores due to the microgeometry of the base metal
K to Mi pores due !o occlusion of hydrogen bubbles and foreign particles from the bath, or residual contaminants on the surface of the base
metal
Figure C.l - Types of pore in electroplated coatings and cause of formation
(after Kutzelnigg and Gioria)
@ IS0
IS0 10308:1995(E)
Annex D
(informative)
Classification of discontinuities in metallic and other inorganic coatings
(1) Pores perpendicular to the coating surface
Pores extending from the
(I) According to type and (a)
localization of the base metal to the surface of
(2) Pores inclined with respect to the coating surface
discontinuity the coating metal
(3) Twisted pores
(I) Pores extending from the base metal surface
Masked pores
(b)
(2) Internal pores reaching neither the base metal nor
the coating surface.
(1) Scratches and cracks extending from the base
Scratches and cracks
(cl
metal surface to the coating surface
(2) Scratches and cracks not reaching the base metal
Macroscopic (visible to the naked eye)
(2) According to size of the (a)
discontinuity
Microscopic (under microscope or at a magnification of x IO)
(b)
Submicroscopic (invisible under a light microscope; their occurrence is connected
(cl
with the coating structure)
Effect of deposition conditions (formation of masked pores or pores extending to
(3) According to cause of (a)
the base metal)
formation of the pores
(b) Effect of the microgeometry of the coated surface
Effect of hydrogen bubbles and small solid particles from the bath incorporated into
(cl
the coating
(d) Effect of contaminants (dirt, grease) not removed from the metal surface
@ IS0
Annex E
(informative)
Classification of methods of testing coating porosity
(1) Ferroxyl test
(a) Immersion tests
(1) Chemical methods
(2) Copper sulfate acid solution test
(3) Cadmium sulfate test
(4) Hydrogen peroxide test
(5) Sodium chloride/hydrogen peroxide solution test
(6) Hot distilled water (95 “C) test
(7) Sodium polysulfide test
(8) Boiling nitric acid test
(9) Acid solution test
(10) Organic indicator test
(b) Solution spreading test (I Ferroxyl test
Filter paper test (I Ferroxyl test
(cl
Organic indicator test
(2
(I) Neutral salt spray test
(d) Solution-fog test
(2) Acetic salt spray test
Gas atmosphere test (1 ) NH,, SO,, H,S, HNO,, S,
H
Anodic treatment ) Ferroxyl test
Electrochemical methods (a) (1
(2)
(1) Photographic paper test
(b) Electrographic test
(2) Gypsum impression test
(3) Gelling media test
(4) Analytical determination
(a) Optical methods
(3) Physical methods
(b) Gas permeability methods
(c) Ultrasonic methods
(d) Autoradiographic and isotope methods
(e) High-voltage or high-frequency methods
...