ASTM D6442-06(2020)

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: D6442 − 06 (Reapproved 2020)
Standard Test Method for
Determination of Copper Release Rate From Antifouling
Coatings in Substitute Ocean Water
This standard is issued under the fixed designation D6442; 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.
1. Scope 1.5 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
1.1 This test method covers the laboratory determination of
only.
the rate at which copper is released from an antifouling (AF)
1.6 This standard does not purport to address all of the
coating in substitute ocean water. The practical limits for
safety concerns, if any, associated with its use. It is the
quantifying copper release rates by this method are from 1.8 to
-2 -1
responsibility of the user of this standard to establish appro-
500 µg cm d . This range may be extended to 0.2 to 500 µg
-2 -1
priate safety, health, and environmental practices and deter-
cm d iftheanalyticalproceduredescribedinAppendixX1is
mine the applicability of regulatory limitations prior to use.
followed.
For specific hazard statements, see Section 7.
NOTE 1—The term “substitute ocean water” is used throughout this
1.7 This international standard was developed in accor-
standard to refer to artificial or synthetic seawater prepared in accordance
dance with internationally recognized principles on standard-
with Practice D1141.
ization established in the Decision on Principles for the
1.2 The procedure contains the preparation steps for the
Development of International Standards, Guides and Recom-
release rate determination of copper from antifouling paints
mendations issued by the World Trade Organization Technical
including apparatus, reagents, holding tank conditions, and
Barriers to Trade (TBT) Committee.
samplingpointdetails.Analysisfortheconcentrationofcopper
insubstituteoceanwaterrequirestheaccuratedeterminationof
2. Referenced Documents
-1
copper at the low parts µg L (parts per billion, ppb) level. To
2.1 ASTM Standards:
detect and correct for reagent impurities, acceptable analytical
D1005 Test Method for Measurement of Dry-Film Thick-
precision standards are necessary. Therefore, the limit of
ness of Organic Coatings Using Micrometers
quantitation (LOQ) for copper in substitute ocean water for the
D1141 Practice for the Preparation of Substitute Ocean
-1
analytical method shall be 10 µg L (10 ppb) or less. The
Water
procedure for determining the LOQ for copper in substitute
D1193 Specification for Reagent Water
ocean water for the analytical method is found in Annex A2.
3. Summary of Test Method
1.3 Asuitable method is described in Appendix X1 (graph-
ite furnace atomic absorption spectroscopy, GF-AAS). Other
3.1 The candidate paint is applied to cylindrical test speci-
analytical methods may be utilized with relevant procedural
mens. The coated specimens are placed in a tank of substitute
-1
changes,asneeded,toaccommodateselectedspecificmethods.
ocean water where the copper levels are kept below 100 µg L
Such methods must meet the limit of quantitation for copper in
by circulating the substitute ocean water through a suitable
-1
substitute ocean water of 10 µg L (10 ppb) or less. See 1.2.
filtration system (see 5.3). At specified intervals, each speci-
men is placed in 1500 mL of substitute ocean water (see
1.4 This results of this test method do not reflect environ-
Section 9 for details) and rotated at 60 revolutions per minute
mental copper release rates for antifouling products, and are
(rpm) for 1 h (or less, see 9.8 for further explanation and
not suitable for direct use in the process of generating
instruction). The rate of copper release from the paint is
environmental risk assessments, environmental loading
determined by measuring copper concentrations of the substi-
estimates, or for establishing release rate limits for regulatory
tute ocean water in the individual measuring containers.
purposes. See also Section 4 on Significance and Use.
3.2 Appendix X1 provides an analytical procedure for
measuring copper concentrations in substitute ocean water.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
Subcommittee D01.45 on Marine Coatings. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Aug. 1, 2020. Published August 2020. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1999. Last previous edition approved in 2012 as D6442 – 06 (2012). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D6442-06R20. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6442 − 06 (2020)
4. Significance and Use 5. Apparatus
5.1 Release Rate Measuring Container—A nominal 2 L ( ⁄2
4.1 This test method is designed to provide a laboratory
gal.) polycarbonate container, approximately 13.5 cm (5.3 in.)
procedure to quantify and characterize the release rates of
in diameter and 19 cm (7.5 in.) high, fitted with three
copperfromantifoulingcoatingsinsubstituteoceanwaterover
polycarbonate rods approximately 6 mm (nominal ⁄4 in.) in
a period of immersion under specified laboratory conditions of
diameter to serve as baffles. Rods shall be evenly spaced on the
constant temperature, pH, salinity, and low copper concentra-
inside circumference of the container to prevent swirling of the
tion. Quantitative measurement of the release rate is necessary
water with the test cylinder during rotation. The rods will be
to help in selection of materials, in providing quality control,
secured to the container walls using acetone or methylene
and in understanding the performance mechanism.
chloride (see Annex A1).
4.2 Results from this test method establish a pattern of
5.2 Constant Temperature Control—A means of maintain-
copper release from an antifouling coating over a minimum of
ing the release rate measuring test containers at a temperature
45 days exposure under controlled laboratory conditions.
of 25 6 1°C during the rotation period (see 9.8).
Copper release rates from antifouling paints in-service vary
5.3 Holding Tank—Aninertplasticcontainerofsuchdimen-
over the life of the coating system depending on the formula-
tion and on the physical and chemical properties of the sions so as to permit immersion of four or more test cylinders;
must be equipped with a system to continuously circulate the
environment. Factors such as differences in berthing locations,
operating schedules, length of service, condition of paint film substitute ocean water in the tank through an activated carbon
filter and optionally an absorbent filter. If an absorbent filter is
surface, temperature, pH, and salinity influence the actual
release rate under environmental conditions. Results obtained used, regenerate the ion-exchange resin following the manu-
facturer’s instructions and wash the resin with substitute ocean
using this test method do not reflect actual copper release rates
that will occur in-service, but provide comparisons of the water prior to use. The rate of water flow and the size of the
filter(s) shall be selected to maintain copper concentrations
release rate of different antifouling formulations in substitute
-1
ocean water under the prescribed laboratory conditions. below 100 µg L . Flow rates should be set to obtain 2 to 8
turnovers per hour.
4.3 By comparison with copper release rate measurements
5.4 The size and geometry of the tanks as well as the
obtained either by direct measurements of copper release rate
positioning of the inflow and outflow ports for the water
from AF coating systems on ship hulls, or copper release rate
circulation system shall be selected to obtain a slow, relatively
measurements from AF coating systems from harbor exposed
uniform flow of substitute ocean water past all test cylinders in
panels, all available data indicate that the results of this test
the tank. Maintain the pH of the substitute ocean water
method (Test Method D6442) significantly overestimate the
between 7.9 and 8.1, the salinity between 33 and 34 parts per
release rate of copper when compared to release rates under
thousand (ppt), and temperature at 25 6 1°C (77 6 2°F).
in-service conditions. Published results demonstrate that this
test method produces higher measurements of copper release
5.5 Test Cylinders—Approximately 6.4 cm (nominal 2 ⁄2
ratethanfromdirectin-situmeasurementsforthesamecoating
in.) outside diameter by 17.8 cm (nominal 7 in.) long polycar-
on in-service ship hulls and harbor-exposed panels. The
bonate pipe or equivalent polycarbonate cylindrical shapes
difference between the results of this test method and the panel
coated with a 10 cm (3.94 in.) band of antifouling paint around
and ship studies was up to a factor of about 30 based on data
the exterior circumference of the test cylinder to provide 200
3,4
for several commercial antifouling coatings. Realistic esti-
cm ofpaintfilmthatcanbeimmersedandfreelyrotatedinthe
mates of the copper release from a ship’s hull under in-service
release rate measuring container (see Note 2).Atop disc, fitted
conditions can only be obtained from this test method where
with a shaft of proper diameter for the rotating device, should
the difference between the results obtained by this test method
be sealed to the cylinder. Seal the bottom of the test cylinder
and the release rate from anAF coating in-service is taken into
with a polycarbonate disc using acetone, methylene chloride or
account.
a polycarbonate cement so as to form a watertight joint. Do not
coat the lower 1 to 2 cm (0.39 to 0.79 in.) of the test cylinder.
4.4 Where the results of this test method are used in the
The test cylinder shall be of such height so that a rotating
process of generating environmental risk assessments, for
device can be attached to rotate the cylinder with the upper end
environmental loading estimates, or for regulatory purposes, it
of the cylinder above the level of the test container immersion
is most strongly recommended that the relationship between
liquid to prevent entry of the immersion liquid into the test
laboratory release rates and actual environment inputs is taken
cylinder (see AnnexA1). It is advisable to weight the cylinder
into account to allow a more accurate approximation of the
by filling with water so that the unit does not have buoyancy.
copper release rate from antifouling coatings under real-life
conditions. This can be accomplished through the application
NOTE 2—When coating release rates are very high, it may be desirable
4 2 -1
tousea5cm band (100 cm ) paint area to avoid exceeding 200 µg L of
of appropriate correction factors.
copper in the measuring containers (see 9.8.1).
3 5
Valkirs, A. O, Seligman, P. F., Haslbeck, E., and Caso, J. S., Marine Pollution A filter cartridge, containing a chelating iminodiacetic (alternative spelling –
Bulletin, Vol 46 (2003), pp 763–779. imminodiacetic) acid ion-exchange resin on a styrene support (nominal particle size
Finnie, A. A.,“Improved Estimates of Environmental Copper Release Rates range approximately 0.300 to 0.850 mm (20 to 50 mesh)) of sufficient capacity to
from Antifouling Products,” Biofouling, Vol. 22 (2006). In press. require regeneration only once a month or less frequently, has been found suitable.
D6442 − 06 (2020)
5.6 Test Cylinder Rotating Device—The device shall be 8. Calibration and Standardization
capable of rotating the test cylinder in the release rate measur-
8.1 Prepare five suitable standards from the copper stock
-1
ing container at 60 6 5 rpm (0.2 6 0.02 m·s , velocity of test
solution (see 6.5) in a medium appropriate to the analytical
cylinder surface). No part of the device shall be immersed in
method.
substitute ocean water.
8.2 Prepare spikes in substitute ocean water at 10, 50 and
-1
5.7 Sample Tubes—60 mL capacity with screw closures (or
200 µg L to cover the working range of the method.
disposable bottles, culture tubes, etc.) made of polycarbonate,
Additional spikes may be prepared at appropriate levels and
polypropylene or borosilicate glass.
appropriate to the analytical technique being used.
5.8 Dispensers—Automatic or repeating for reagents.
8.3 At the beginning of each instrument run, analyze a
suitable blank and standards in order to establish that the
5.9 pH Meter, with a suitable electrode.
response of the instrument is linear. Plot separate calibration
5.10 Appropriate Hydrometer or Salinometer.
curves for each analysis of the standards (instrument response
5.11 Appropriate Volumetric Flasks. versus copper concentration) and calculate the slope, intercept,
and correlation coefficient for each curve using least squares fit
5.12 Disposable Polypropylene Syringes, 60 mL.
or another appropriate procedure.
5.13 Syringe Filters, 0.45 µm.
8.4 Analyze the following:
8.4.1 Substitute Ocean Water Blank—Acidify, extract and
6. Reagents and Materials
analyze as specified (see 9.10 and 9.11) for test samples, to
6.1 Purity of Reagents—All reagents and cleaning agents
establish baseline.
are to be reagent grade or better.
8.4.2 Spiked Substitute Ocean Water Samples—Acidify, ex-
tract and analyze as specified (see 9.10 and 9.11) for the test
6.2 Purity of Water—Distilled water conforming to Type II
samples to determine extraction efficiency. Recovery must be
of Specification D1193.
-1
100 % 6 10 % for the 50 µg L spike and spikes of higher
6.3 Substitute Ocean Water—Artificial ocean water in ac-
concentration. Recovery must be 100 % 6 15 % for spikes
-1
cordance with Practice D1141, section on Preparation of
with a concentration below 50 µg L .
Substitute Ocean Water, or a proprietary equivalent with a
salinity of 33 to 34 ppt and pH 7.9 to 8.1.
9. Procedure
6.4 Extraction Media—Activated carbon and, optionally, a
9.1 Cleanpolycarbonatewarewithtapwaterthenrinsewith
chelating ion-exchange resin, iminodiacetic (imminodiacetic)
deionized water. All glass laboratory ware used for copper
acid exchange resin on a styrene support, nominal particle size
release rate measurements must be treated as follows: clean
range approximately 0.300 to 0.850 mm (20 to 50 mesh) (see
thoroughly by soaking in 10 % HCl for a minimum of 6 h.
5.3).
Cleaning can also be accomplished by soaking in concentrated
HCl for ⁄2 h. Rinse laboratory ware thoroughly with deionized
6.5 Copper Standards—Prepare standards using a stock
-1
or distilled water and allow to dry. Prepare all samples, blanks
solution of copper, 1000 mg L (1000 ppm), or other concen-
and standards in laboratory ware treated in this manner.
trationsuitabletotheselectedanalyticaltechnique(seeSection
Disposable materials (pipettes, tips, centrifuge tubes, etc.) do
8).
not have to be acid-washed before use.
6.6 Nitric Acid (HNO )—Concentrated, high purity grade.
9.2 Prepare the exposure surfaces of three replicate test
6.7 Hydrochloric Acid (HCl), 10 %, v/v, aqueous solution.
cylinders to provide a suitable surface for adhesion of the paint
to be applied. The surface area to be painted shall be lightly
6.8 Sodium Hydroxide (NaOH), 1 N, aqueous solution.
abraded with 200-grit sandpaper to promote adhesion. Before
6.9 Deionized Water.
coating, wipe abraded area to remove dust. Mask the surfaces
6.10 Sodium Chloride (NaCl), 5 M, aqueous solution.
to remain uncoated (including the bottom 1 to 2 cm of the
exterior circumferential surface of the test cylinder). Identify
7. Hazards
eachcylindertoagreewithcoatingsamplecodeordesignation.
7.1 Warning—Antifouling paints may contain toxic mate- 9.3 Paints shall be manufactured a minimum of seven days
rials that could cause skin and eye irritation on contact and
prior to testing. Also, test paints shall not be allowed to age
adverse physiological effects if ingested or inhaled. See anti- beyond the manufacturer’s recommended shelf life. Provide
fouling coating supplier’s Material Safety Data Sheet.
typical storage conditions during aging, that is, sealed in a
container commonly used for sale and held at 20 to 30°C.
7.2 In the preparation of test specimens and the application
of various types of paints, the use of appropriate protective 9.4 Apply antifouling paint to the exterior circumferential
clothing and equipment is required consistent with local, state, surface of three replicate test cylinders to produce a continuous
and federal government regulations, and recognized industrial band of antifouling paint with an exposure surface of 200 cm .
and technical standards. Spills, overspray, and unused material Ensure surface is completely covered with finished dry film
should not be flushed down the drain, but should be disposed coating of 100 to 200 µm (0.004 to 0.008 in.). If, during the
of as hazardous waste. test, the film thickness is expected to fall below 50 µm, then a
D6442 − 06 (2020)
-1
greater thickness of paint should be applied. Alternative be >200 µg L , the rotation period for the next measurement
surface areas are allowed when 200 cm is not appropriate – shall be reduced to less than 1 h, with the goal of ultimately
deviations from the 200 cm surface area shall be noted in the building the rotation period back up to 1 h. The amount by
final report. Follow manufacturer’s instructions with respect to which the rotation period is reduced shall be estimated based
mixing and drying. At a minimum, mechanically shake until
on familiarity with the coating being evaluated and experience
the paint appears homogeneous. Apply using a brush, sponge with the test method, and shall take into consideration the
-1
paint applicator, or spray as recommended by the manufac-
degree to which the measurement exceeded 200 µg L .Ifthe
-1
turer. If the paint is marketed only in spray cans, then apply as next measurement also exceeds 200 µg L , the period of
a spray. If applied by brush, the film shall not show brush
rotation shall be further reduced until the result falls under 200
-1
marks. After the final application, allow the paint to dry for 7
µgL .Onceameasurementhasbeentakenthatfallsunder200
-1
6 1 day at 25 6 2°C and 30 to 80 % relative humidity. Include
µg L , the period of rotation shall be incrementally re-adjusted
application method and coating thickness in report.
back up to a maximum of1hatthe earliest possible point in
the testing.
9.5 Measure the initial dry film thickness using a suitable
9.8.2 Any measurements taken where either the concentra-
non-destructive procedure found in Test Method D1005 or
-1
tion in the individual measuring container was >200 µg L or
other suitable non-destructive method and report the method
where the period of rotation was less than 1 h should be used
used. Remove masking promptly after paint is dry. At the
to calculate release rate, and they must be recorded in the final
conclusion of the test, allow the cylinders to dry for at least 12
report.
h at ambient conditions and measure the film thickness again.
9.6 After the drying period, place one or more sets of three 9.9 If testing beyond the minimum 45 days requirement is
desired, the study may be extended. During the extended test,
replicate cylinders coated with a test paint, and one blank
(unpainted) cylinder in a holding tank. The painted surface on remove the cylinders from the holding tank at least once every
7daystomakeameasurementofthereleaserateinaccordance
the cylinders must be completely submerged. Cylinders must
be stationary, and positioned so that substitute ocean water with the above procedure.
moving through the tank will flow around each cylinder.
9.10 At the completion of the cylinder rotation, transfer the
9.7 Maintain the substitute ocean water within the pre-
cylinder back to the holding tank. Withdraw approximately a
scribed range (see 5.4) by monitoring and adjusting the pH,
100 mL subsample of the test substitute ocean water from the
salinity, and temperature of the substitute ocean water in the
measuringcontainer.Acidifythesubsamplebyadding0.10mL
holding tank at least every third day from the start through the
of high purity concentrated nitric acid per 100 mL of sub-
end of the study. Monitor the pH and adjust if necessary using
sample and agitate for at least 10 minutes (expected pH ≤2).
either dilute NaOH or dilute HCl. Monitor the salinity and
Then, draw 50 mL of the acidified subsample into a plastic
adjust if necessary by adding distilled water or 5 M NaCl.
syringe. Filter through a 0.45-µm filter while transferring the
Determine the copper concentration in the holding tank at each
subsample into a properly labeled sample tube (approximately
sampling point. When copper levels increase, replace or
60 mL). The sample can be refrigerated (approximately 5°C)
regenerate the extraction media before the copper concentra-
for up to 14 days if necessary before analysis.
-1
tion exceeds 100 µg L .
9.11 Analyze the samples using an appropriate analytical
NOTE 3—More frequent monitoring and adjustment of pH and salinity
technique. The method should have a sensitivity (LOQ) for
may be required to maintain the substitute ocean water within the -1
copper in substitute ocean water of 10 µg L or less and show
prescribed range during the early stages of a study while the system
spikerecoveriesasindicatedin8.4.2.AmethodusingGF-AAS
equilibrates.
can be found in Appendix X1.
9.8 At 1, 3, 7, 10, 14, 21, 24, 28, 31, 35, 38, 42, and 45 day
intervals, transfer all cylinders in a given set from the holding
10. Calculation
tank(s) into individual measuring containers, each containing
10.1 Calculate the copper concentration in each acidified
1500 mL of substitute ocean water that, prior to use, has been
subsample(see9.10)basedoninstrumentresponseforsamples
passed through a filter containing the extraction media. Ran-
and blanks.
domly assign cylinders (control and painted) to measuring
containers on each measurement day. When transferring NOTE 4—If copper is detected in the substitute ocean water used to fill
the individual sampling containers, this shall be reflected in the calcula-
cylinders, lift the cylinder out of the holding tank, allow
tion.
substitute ocean water to drain off, install the cylinder into the
rotating device and submerge the painted area into the test
10.2 Calculation of the release rate at each data point
substitute ocean water. Immediately start rotation of the cylin-
(sampling day):
-2 -1
der at 60 6 5 rpm and continue rotation for 1 h (see 9.8.1).
10.2.1 Calculate the release rate (µg cm d ) for each
When transferring the cylinders do not touch, or in any way
individual test cylinder.
damage,thepaintfilmanddonotallow
...