ASTM D7855/D7855M-13
(Test Method)Standard Test Method for Determination of Mold Growth on Coated Building Products Designed for Interior Applications Using an Environmental Chamber and Indirect Inoculation
Standard Test Method for Determination of Mold Growth on Coated Building Products Designed for Interior Applications Using an Environmental Chamber and Indirect Inoculation
SIGNIFICANCE AND USE
5.1 An accelerated test for determining the resistance of interior coated building products to mold growth is useful in estimating the relative performance for use in interior environments under conditions favorable to fungal growth.
5.2 Static or environmental chambers provide controlled laboratory micro-environment conditions. These chambers are not intended to duplicate room conditions, and care must be taken when interpreting the results. Static chambers are not a substitute for dynamic chambers or field studies.
SCOPE
1.1 This test method covers an environmental chamber and the conditions of operation to evaluate in a 4-week period the relative resistance to mold growth and microbial surface defacement on coated building products designed for interior application using an indirect inoculation method. The apparatus is designed so it can be easily built or obtained by any interested party.
1.2 This test method can be used to evaluate the comparative resistance of coated building products to accelerated mold growth. Ratings do not imply a specific time period that the coated building product will be free of fungal growth during installation in an interior environment.
1.3 This test method is not intended for use in the evaluation of public health claims.
1.4 The test method is intended for the accelerated evaluation of mold growth on a coated building product designed for interior use. This method is not intended for evaluation of surfaces designed for exterior applications or uncoated surfaces. Use of this test method for evaluating exterior performance has not been validated, nor have the limitations for such use been determined.
1.5 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.
1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Designation: D7855/D7855M − 13
Standard Test Method for
Determination of Mold Growth on Coated Building Products
Designed for Interior Applications Using an Environmental
Chamber and Indirect Inoculation
This standard is issued under the fixed designation D7855/D7855M; 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 2. Referenced Documents
1.1 This test method covers an environmental chamber and 2.1 ASTM Standards:
the conditions of operation to evaluate in a 4-week period the D16 TerminologyforPaint,RelatedCoatings,Materials,and
relative resistance to mold growth and microbial surface Applications
defacement on coated building products designed for interior D1193 Specification for Reagent Water
application using an indirect inoculation method. The appara- D6329 Guide for Developing Methodology for Evaluating
tus is designed so it can be easily built or obtained by any the Ability of Indoor Materials to Support Microbial
interested party. Growth Using Static Environmental Chambers
E177 Practice for Use of the Terms Precision and Bias in
1.2 This test method can be used to evaluate the compara-
ASTM Test Methods
tive resistance of coated building products to accelerated mold
E691 Practice for Conducting an Interlaboratory Study to
growth. Ratings do not imply a specific time period that the
Determine the Precision of a Test Method
coated building product will be free of fungal growth during
installation in an interior environment.
3. Terminology
1.3 Thistestmethodisnotintendedforuseintheevaluation
3.1 Definitions—For definitions of terms refer to Terminol-
of public health claims.
ogy D16.
1.4 The test method is intended for the accelerated evalua-
3.2 Definitions of Terms Specific to This Standard:
tion of mold growth on a coated building product designed for
3.2.1 chamber control, n—open Petri dish containing appro-
interior use. This method is not intended for evaluation of
priate agar to demonstrate viability of fungal organisms within
surfaces designed for exterior applications or uncoated sur-
the environmental chamber.
faces. Use of this test method for evaluating exterior perfor-
3.2.2 coated building product, n—a building material hav-
mance has not been validated, nor have the limitations for such
ing a liquid, liquefiable or mastic composition that is converted
use been determined.
to a solid protective, decorative, or functional adherent film
1.5 The values stated in either SI units or inch-pound units
after application as a thin layer onto a building fabric.
are to be regarded separately as standard. The values stated in
3.2.3 interior, n—any surface not exposed to exterior envi-
each system may not be exact equivalents; therefore, each
ronments in end use.
system shall be used independently of the other. Combining
3.2.4 interior finish, n—interior wall and ceiling finish and
values from the two systems may result in non-conformance
interior floor finish.
with the standard.
3.2.5 material control, n—untreated representative sub-
1.6 This standard does not purport to address all of the
strate.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.2.6 sample, n—a portion of material taken from a larger
priate safety and health practices and determine the applica-
quantity for the purpose of estimating properties or composi-
bility of regulatory limitations prior to use.
tion of the larger quantity.
3.2.7 sample tests, n—a group of samples (one or more).
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Subcommittee D01.28 on Biodeterioration. contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Current edition approved Oct. 1, 2013. Published November 2013. DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D7855_D7855M–13. the ASTM website.
Copyright ©ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA19428-2959. United States
D7855/D7855M − 13
3.2.8 test run, n—the evaluation of coated building products perature and humidity monitoring without opening the cham-
in accordance with the procedure outlined in this test method. ber lid. Examples would include wireless or wired probes.
3.2.9 test specimen, n—a portion of a test unit needed to 7.1.1 The test chamber shall be designed so that no conden-
sate forming on the top interior surface will drip onto the test
obtain a single test determination.
specimens. For stand-alone chambers, this can be accom-
4. Summary of Test Method
plished by designing the top so that the interior surface is at an
angle of at least 30 degrees, relative to the plane of the bottom
4.1 This test method is an indirect inoculation to a coated
of the chamber. A sheet of polycarbonate secured at an angle,
interior building product of two fungal organisms, Aspergillus
or hinged or joined sheets of polycarbonate attached to the
nigerand Penicillium citrinum.Testspecimensareplacedinan
underside of the lid will direct the condensation away from the
environmental chamber maintained at 30 6 2°C [86 6 3.6°F]
test samples. Condensation inside the test chamber is not a
and at greater than 90 % relative humidity for four weeks.
concern as it indicates that humidity is being maintained.
Humidity is maintained by adding sufficient sterile DI water to
the bottom of the covered test chamber. A continuous fungal 7.1.1.1 Anon-corrosive open grid is placed at the bottom of
inoculation is provided by open Petri dishes supporting seven the test chamber above the water level supporting 100 by 15
day cultures of the two test organisms placed on a rack below
mm [4 by ⁄8 in.] sterile Petri dishes alternating the two fungal
the test pieces. Test specimens are removed from the chamber organisms. See Fig. 1 for non-corroding open grid example.
after four weeks exposure and examined for fungal growth.
Place sufficient Petri dishes on the rack to fill the grid. The
The evaluation is a macroscopic inspection of the test pieces
plastic grid designed to cover recessed ceiling fixtures or
with indirect lighting.
similar works well.
7.1.1.2 Position test specimens by suspending them from
5. Significance and Use
rods using plastic cable ties. Samples must be 50 to 100 mm [2
5.1 An accelerated test for determining the resistance of
to 4 in.] above the inoculated Petri dishes. The minimum
interior coated building products to mold growth is useful in
distance between adjacent specimens and between test speci-
estimating the relative performance for use in interior environ-
mens and chamber walls shall be at least 25 mm [1 in.].
ments under conditions favorable to fungal growth.
Materials used as the rods or mounting racks shall be non-
corroding and of sufficient strength to support specimens
5.2 Static or environmental chambers provide controlled
throughout the duration of the test. Use of engineered plastics
laboratory micro-environment conditions. These chambers are
such as polycarbonate has been found suitable. Fig. 2 shows a
not intended to duplicate room conditions, and care must be
photo of typical chamber construction. Fig. 3 illustrates use of
taken when interpreting the results. Static chambers are not a
cable ties to hang test specimens from rods.
substitute for dynamic chambers or field studies.
7.2 Measurement Instruments, capable of accurate and pre-
6. Interferences
cise measures of temperature and humidity. See Section 12.
6.1 Proper lab ventilation, hygiene, and aseptic technique
7.3 Incubator or Controlled Temperature Room maintained
must be followed to ensure fungal cultures are pure and no
at 30 6 2°C [86 6 3.6°F].
cross contamination of fungal strains or growth media occurs.
6.2 The exposure of test specimens to environmental con-
ditions including temperature, humidity, and light can impact
test results. To minimize variability of test results consistent
handling and storage of test specimens is important.
7. Apparatus
7.1 Environmental Chamber—Anon-corrosive covered box
containing standing water placed in an incubator at 30 6 2°C
[86 6 3.6°F] will expose the test specimens to a controlled
environment of temperature and humidity. Containers found
suitable include glass, polycarbonate or other plastic storage
containers which are generally available. For example a
nineteen liter container measuring approximately 460 mm long
by 300 mm wide by 230 mm high [18 in. long by 12 in. wide
by 9 in. high] can accommodate fifteen 75 by 100 mm [3 by 4
in.] test specimens suspended from rods using cable ties.
Opaque chambers shall have a viewing port that permits
observation of chamber controls. Chamber shall permit tem-
The 5.0 Gallon Rectangular Food Storage Containers from various suppliers FIG. 1 Non-corroding Open Grid for Placement in Bottom of the
have been found to work well. Environmental Chamber
D7855/D7855M − 13
8.3 Material Controls, if available, see 3.2.
8.4 Purity of Reagents—Water shall be distilled water or
higher purity. See Specification D1193.
8.5 Sabouraud Dextrose Agar or media appropriate for
fungi selected.
8.6 Sterile Disposable Cotton-tipped Swabs.
8.7 Sterile 100 by 15 mm (4 by ⁄8 in.) Petri Dishes.
9. Hazards
9.1 This test must be performed by trained individuals in
laboratories specially equipped for conducting microbiological
tests.
FIG. 2 Typical Environment Chamber Set Up
10. Sampling and Test Specimens
10.1 Sampling shall be representative of the product being
evaluated.
10.2 Test Specimens:
10.2.1 Aminimum of three test specimens shall be cut from
each sampled coated interior building product to be evaluated.
The number of test specimens will be reported in the results.
10.2.2 Additional replicates should be available to rerun the
test if necessary.
11. Preparation of Apparatus and Inoculum
11.1 Cleanandsanitizetheenvironmentalchamberspriorto
use. Add approximately 25 mm [1 in.] of water to the bottom
of the container. Ensure the water level is sufficient to provide
FIG. 3 Cable Ties used to Hang Test Specimens from Rods Inside
humidity through the duration of the test. If the test specimens
of the Environmental Chamber
absorb the water or water is lost through the seal of the lid,
additional water must be added to ensure the relative humidity
8. Reagents and Materials
remains at 90 % or greater for the duration of the test. The
water level should be at least 25 mm [1 in.] below the rack
8.1 Cultures—Aspergillus niger,ATCC 6275 or IMI/CABI
supporting the Petri dishes of the fungal test organisms.
Bioscience 45551, Penicillium citrinum ATCC 9849 or IMI/
NOTE 2—Petroleum jelly or similar product may be used between the
CABI Bioscience 321326.
lid and the container to improve the seal.
8.1.1 Selection of the appropriate test organisms is ex-
11.2 Insert the temperature/humidity sensor or data logger
tremely important and must be representative of the types of
intotheenvironmentalchamberandsetinanincubatororother
organisms found or likely to be found on the interior coated
temperature controlled chamber set at 30 6 2°C [86 6 3.6°F]
buildingproductsbeingtested.Theorganismsnamedin8.1are
to equilibrate for 24 h before starting the test. Record the
not representative of all potential fungal organisms that may be
temperature and humidity not less than every 7 days. If
found growing on interior coated building products. Other
temperature and humidity readings are outside the parameters
fungal organisms may also be used in separate evaluations, but
set in 4.1, results shall be discarded and testing restarted with
the specified organisms in 8.1 shall be used and reported. The
new test pieces.Temperature and humidity measurements shall
potential for interferences between non-specified fungal test
be included in the final report.
organisms shall be considered when using organisms other
than those named in 8.1.
11.3 Prepare spore suspensions of each test fungi from 7 to
14 day old well sporulating cultures. Maturation of the fungal
NOTE 1—Subcommittee D01.28 reviewed the published study listed in
organisms designated in 8.1 may not occur at the same rate.
the Reference section of this document and determined the organisms in
8.1 as appropriate. Penicillium citrinum typically takes longer to sporulate than
Aspergillus niger so cultivation should begin earlier assuring
8.2 Chamber Controls—Open PDA plates placed on the
both organisms are sporulating when placed in the environ-
bottom of the chamber at opposite corners and near the center.
mental chamber. Stock cultures may be kept for no more than
four months at 3 to 10°C [37 to 50°F].
Cultures can be obtained from American Type Culture Collection, P.O. Box
11.3.1 Topreparetheinoculum,dislodgefungalsporesfrom
1549, Manassass, VA 20108 or Mycological Services, P.O. Box 1056,
agar by rolling a sterile cotton-tipped swab moistened with
Crawfordsville, IN 47933.
sterile distilled water across the sporulating fungi. Transfer the
Cultures can be obtained from IMI/CABI Bioscience, Nosworthy Way,
Wallingford, Oxfordshire, OX108DE UK. spores from the cotton tipped swab to a test tube containing 5
D7855/D7855M − 13
FIG. 4 Example of Sporulating Fungal Plates Arranged in an Alternating Pattern in the Environmental Chamber
ml of sterile distilled water and a nontoxic wetting agent for 12.2 Instruments for humidity measurement shall measure
each test organism. Blend the fungal spore suspension on the with a precision of 65%RHat95%RH.
vortex mixer for 10 s to liberate spores from hyphae and to
12.3 Both types of measurement instruments shall be cali-
break up spore clumps. Repeat this procedure for each fungal
brated no less than annually by a laboratory using standards
organism used.
that are documented traceable to NIST standards.
11.4 Pour 25 mL [1.0 oz.] of Sabouraud Dextrose or
13. Conditioning
appropriateagarfortestorganismsnamedin8.1into100by15
mm [4 by ⁄8 in.] sterile Petri dishes and allow the agar to 13.1 Equilibrate triplicate test specimens of each sample
solidify. Prepare sufficient Petri dishes to fill the rack placed at
and condition to room temperature before starting test.
the bottom of each environmental chamber. For the chamber
14. Procedure
size referenced in 7.1, twelve 100 by 15 mm [4 by ⁄8 in.] Pe
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