ASTM D6903-07(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: D6903 − 07 (Reapproved 2020)
Standard Test Method for
Determination of Organic Biocide Release Rate From
Antifouling Coatings in Substitute Ocean Water
This standard is issued under the fixed designation D6903; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope ocean water are given in Appendix X1 – Appendix X3,
respectively. Other methods may be used provided that they
1.1 This test method covers the laboratory determination of
meet the appropriate criteria given in Annex A2.
the rate at which organic biocide is released from an antifoul-
ing coating exposed in substitute ocean water. The test is run
1.5 Whenthereleaserateofahighlyphotosensitiveorganic
entirely in the laboratory under controlled conditions of pH,
biocide is being determined, steps must be taken to protect the
temperature, salinity, and hydrodynamics. Analytical proce-
apparatus and samples from exposure to natural and artificial
dures are provided for the determination of the release rate of
visible light sources. Any such requirement for these steps to
4,5-dichloro-2-n-octylisothiazolin-3-one (DCOIT), zinc and
be taken for a particular biocide is indicated in Annex A2.
copper pyrithione (ZPT and CuPT), and N-cyclopropyl-N'-(1,
1-dimethylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine 1.6 Thepracticallimitsforquantifyingbiocidereleaserates
-2 -1
(CDMTD).At predetermined intervals, substitute ocean water bythismethodarefrom4.5to500 µgcm d forDCOIT,0.36
-2 -1 -2 -1
samples are analyzed for leached biocide using a suitable
to 500 µgcm d for CuPT, 0.36 to 500 µgcm d for ZPT,
-2 -1
analytical technique.
and 2.7 to 500 µgcm d for CDMTD. These ranges may be
-2 -1
extended to 3.8 to 500 µgcm d for DCOIT, 0.16 to 500 µg
1.2 In cases in which the antifouling coating contains both
-2 -1 -2 -1
cm d for CuPT, 0.2 to 500 µgcm d for ZPT, and 2.2 to
an organic biocide and a copper-based biocide, the release rate
-2 -1
500 µgcm d for CDMTD if the procedures described in
of copper may optionally be concurrently determined accord-
Appendix X1 – Appendix X3 (as appropriate) are followed.
ing to the procedure found in Test Method D6442.
The quantitation of release rates lower than these ranges will
1.3 The procedure contains the preparation steps for the
require the use of analytical methods with lower limits of
determination of the release rate of biocide in substitute ocean
quantitation than those specified in Annex A2.
water from antifouling paints including apparatus, reagents,
holding tank conditions, and sampling point details. The
1.7 The results of this test method do not reflect environ-
procedure calls for the accurate determination of organic
mental biocide release rates for antifouling products, and are
biocide concentrations in substitute ocean water at the low µg
not suitable for direct use in the process of generating
-1
L (parts per billion, ppb) level. To detect and correct for
environmental risk assessments, environmental loading
reagent impurities and allow a suitable level of analytical
estimates, or for establishing release rate limits for regulatory
precision to be achieved, the analytical method to be used for
purposes. See also Section 4.
the determination of the concentration of organic biocide in
1.8 The values stated in SI units are to be regarded as the
substitute ocean water must meet the acceptability criteria
given in Annex A2. Where Annex A2 specifies a limit of standard. The values given in parentheses are for information
only.
quantitation(LOQ),theprocedurefordeterminingtheLOQfor
the organic biocide in substitute ocean water by the analytical
1.9 This standard does not purport to address all of the
method presented in Annex A3 is to be followed.
safety concerns, if any, associated with its use. It is the
1.4 Suitable analytical methods that use high-performance
responsibility of the user of this standard to establish appro-
liquid chromatography (HPLC) for determining the concentra-
priate safety, health, and environmental practices and deter-
tion of DCOIT, ZPT and CuPT, and CDMTD in substitute
mine the applicability of regulatory limitations prior to use.
1.10 This international standard was developed in accor-
1 dance with internationally recognized principles on standard-
This test method is under the jurisdiction of ASTM Committee D01 on Paint
andRelatedCoatings,Materials,andApplicationsandisthedirectresponsibilityof
ization established in the Decision on Principles for the
Subcommittee D01.45 on Marine Coatings.
Development of International Standards, Guides and Recom-
Current edition approved Aug. 1, 2020. Published August 2020. Originally
mendations issued by the World Trade Organization Technical
approved in 2007. Last previous edition approved in 2013 as D6903 – 07 (2013).
DOI: 10.1520/D6903-07R20. Barriers to Trade (TBT) Committee.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6903 − 07 (2020)
2. Referenced Documents temperature, pH, and salinity influence the actual release rate
2 under environmental conditions. Results obtained using this
2.1 ASTM Standards:
test method do not reflect actual biocide release rates that will
D1005Test Method for Measurement of Dry-Film Thick-
occur in service, but provide comparisons of the release rate
ness of Organic Coatings Using Micrometers
characteristics of different antifouling formulations in substi-
D1141Practice for the Preparation of Substitute Ocean
tute ocean water under the prescribed laboratory conditions.
Water
D1193Specification for Reagent Water 4.3 By comparison with published copper and organotin
4,5
D6442Test Method for Determination of Copper Release release rate data obtained either by direct measurements
Rate From Antifouling Coatings in Substitute Ocean from ship hulls or release rate measurements from harbor
Water exposed panels, all data indicate that the results of this generic
rotating-cylinder test method significantly overestimate the
2.2 U.S. Federal Standard:
release rate of biocide when compared to release rates under
40 CFR 136,Appendix B, revision 1.11
in-service conditions. For example, published results demon-
3. Summary of Test Method
strate that this generic test method produces higher measure-
mentsofcopperandorganotinreleaseratesthanfromdirectin
3.1 The candidate paint system is applied to the cylindrical
situmeasurementsforthesamecoatingonin-serviceshiphulls
test specimens. The coated specimens are placed in a tank of
and harbor-exposed panels. The difference between the results
substitute ocean water in which the levels of organic biocide
of this test method and the panel and ship studies was up to a
and copper (where the coating also contains a biocidal copper
-1
factorofabout30basedoncopperreleaseratedataforseveral
compound) are kept below 100 µgL by circulating the
4,6
commercial antifouling coatings. No direct release rate data
substitute ocean water through a suitable filtration system (see
from ship hulls or harbor-exposed panels have been generated
5.1.3).At specified intervals, each specimen is placed in 1500
to-date for the biocides covered by this method. However, the
mL of substitute ocean water (see Section 8 for details) and
expectation is that the results of this test method, when
rotatedat60rpmfor1h(orless,see8.7forfurtherexplanation
compared with the direct measurements from ship hulls and
and instruction). The rate of biocide release from the paint is
harbor-exposed panels, could follow the same trend. Realistic
determined by measuring concentrations of the biocide in the
estimates of the biocide release from a ship’s hull under
substitute ocean water in the individual measuring containers.
in-service conditions can only be obtained from this test
3.2 Annex A2 provides acceptance criteria for analytical
method where the difference between the results obtained by
procedures for measuring the concentration of specific organic
this test method and the release rate of an antifouling coating
biocides in substitute ocean water. Suitable methods are
in service is taken into account.
providedinAppendixX1–AppendixX3.Alternativemethods
4.4 Where the results of this test method are used in the
may be used provided that they meet the acceptance criteria
process of generating environmental risk assessments, for
given in Annex A2.
environmental loading estimates, or for regulatory purposes, it
is most strongly recommended that the relationship between
4. Significance and Use
laboratory release rates and actual environment inputs is taken
4.1 This test method is designed to provide a laboratory
into account to allow a more accurate approximation of the
procedure to quantify and characterize changes in the release
biocide release rate from antifouling coatings under real-life
rate of organic biocide from antifouling coatings that occur
conditions. This can be accomplished through the application
during a period of immersion under specified laboratory
of appropriate correction factors.
conditions of constant temperature, pH, salinity, and hydrody-
namics. Quantitative measurement of biocide release rate is
5. Apparatus
necessary to help in selection of materials, providing quality
5.1 Sample Generation—SeeAnnexA2forguidanceonany
control, and understanding the performance mechanism.
particular materials restriction and handling requirements re-
4.2 Results from this test method establish a pattern of
lating to each organic biocide.
biocidereleasefromanantifoulingcoatingoveraminimumof
5.1.1 Release Rate Measuring Container—A nominal 2-L
45 days exposure under controlled laboratory conditions.
( ⁄2-gal) container made of an inert material, approximately
Biocide release rates of antifouling paints in-service vary over
13.5 cm (5.3 in.) in diameter and 19 cm (7.5 in.) high, is fitted
thelifeofthecoatingsystemdependingontheformulationand
withthreerodsalsomadeofaninertmaterial,approximately6
on the physical and chemical properties of the environment.
mm (nominal ⁄4 in.) in diameter to serve as baffles. Rods shall
Factors such as differences in berthing locations, operating
be evenly spaced on the inside circumference of the container
schedules, length of service, condition of paint film surface,
to prevent swirling of the water with the test cylinder during
2 4
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Valkirs,A. O., Seligman, P. F., Haslbeck, E., and Caso, J. S., Marine Bulletin,
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Vol. 46 (2003), pp. 763–779.
Standards volume information, refer to the standard’s Document Summary page on Champ,M.A.andSeligman,P.F., Organotin: Environmental Fate and Effects,
theASTM website. Chapter 19 — Measurement and Significance of the Release Rate for Tributyltin,
AvailablefromU.S.GovernmentPrintingOfficeSuperintendentofDocuments, (1996) Chapman and Hall, pp 383–403.
732 N. Capitol St., NW, Mail Stop: SDE, Washington, DC 20401, http:// Finnie,A.A.,ImprovedEstimatesofEnvironmentalCopperReleaseRateFrom
www.access.gpo.gov. Antifouling Coatings, Biofouling, Vol. 22 (2006), pp 279–291.
D6903 − 07 (2020)
rotation. The rods will be secured to the container walls using bottom-end can be used. Do not coat the lower 1 to 2 cm (0.39
an inert adhesive. The material of construction of the release to 0.79 in.) of the test cylinder. The test cylinder shall be of
rate measuring container and rods for use with any particular such height so that a rotating device can be attached to and
biocide shall be as specified in A2.3. When the release rate of rotatethecylinderwiththeupperendofthecylinderabovethe
a photosensitive material is to be determined, the container level of the test container immersion liquid to prevent entry of
shall be protected from light. The requirement to protect the theimmersionliquidintothetestcylinder(seeAnnexA1).The
release rate container from light for any particular organic material of construction of the test cylinder (including the
biocide is indicated in A2.4. bottomend-disk)forusewithanyparticularbiocideshallbeas
specified in A2.3. It is advisable to weight the cylinder by
NOTE1—Theresultsofthistestmethodwillbeadverselyaffectedifthe
filling with water so that the unit does not have buoyancy.
biocide is strongly adsorbed or absorbed by the release rate measuring
container or the test cylinder, or both. Where the release rates of two or
NOTE 2—When coating release rates are very high, it may be desirable
moredifferentbiocidesaretobeconcurrentlydeterminedfromasingleset 2 -1
to use a 5-cm band (100-cm paint area) to avoid exceeding 200 µgL
ofmeasurements,thereleaseratemeasuringcontainer,associatedrodsand
of organic biocide in the measuring containers (see 8.7.1).
the test cylinders must all be made of a material that is inert to all of the
biocides, otherwise repeat testing (different cylinders and measuring 5.1.6 Test Cylinder Rotating Device—The device shall be
containers) for each biocide will be required.
capable of rotating the test cylinder in the release rate measur-
-1
ing container at 60 6 5 rpm (0.2 6 0.02 m s , velocity of test
5.1.2 Constant Temperature Control—This control is a
cylinder surface). No part of the rotating device shall be
means of maintaining the release rate measuring containers at
immersed in substitute ocean water.
atemperatureof25 61°Cduringtherotationperiod(see8.7).
5.1.7 pH Meter, with a suitable electrode.
5.1.3 Holding Tank—This tank is an inert plastic container
5.1.8 Appropriate Hydrometer or Salinometer.
of such dimensions so as to permit immersion of four or more
test cylinders and must be equipped with a system to circulate
5.2 Analysis of Leachate—Suitable analytical procedures
the seawater continuously in the tank through an activated
are provided for the determination of the release rate of
carbon filter and, optionally, an absorbent filter. If an absor-
4,5-dichloro-2-n-octylisothiazolin-3-one (DCOIT), zinc and
bent filter is used, regenerate the ion exchange resin following
copper pyrithione (ZPT and CuPT), and N-cyclopropyl-N'-(1,
the manufacturer’s instructions and wash the resin with sub-
1-dimethylethyl)-6-(methylthio)-1,3,5-triazine-2,4-diamine
stitute ocean water before use. The rate of water flow and the
(CDMTD). Refer to Appendix X1 – Appe
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