ASTM D7855/D7855M-13(2021)

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: D7855/D7855M − 13 (Reapproved 2021)
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 1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard-
1.1 This test method covers an environmental chamber and
ization established in the Decision on Principles for the
the conditions of operation to evaluate in a 4-week period the
Development of International Standards, Guides and Recom-
relative resistance to mold growth and microbial surface
mendations issued by the World Trade Organization Technical
defacement on coated building products designed for interior
Barriers to Trade (TBT) Committee.
application using an indirect inoculation method. The appara-
tus is designed so it can be easily built or obtained by any
2. Referenced Documents
interested party.
2.1 ASTM Standards:
1.2 This test method can be used to evaluate the compara-
D16TerminologyforPaint,RelatedCoatings,Materials,and
tive resistance of coated building products to accelerated mold
Applications
growth. Ratings do not imply a specific time period that the
D1193Specification for Reagent Water
coated building product will be free of fungal growth during
D6329Guide for Developing Methodology for Evaluating
installation in an interior environment.
the Ability of Indoor Materials to Support Microbial
1.3 Thistestmethodisnotintendedforuseintheevaluation
Growth Using Static Environmental Chambers
of public health claims.
E177Practice for Use of the Terms Precision and Bias in
ASTM Test Methods
1.4 The test method is intended for the accelerated evalua-
E691Practice for Conducting an Interlaboratory Study to
tion of mold growth on a coated building product designed for
Determine the Precision of a Test Method
interior use. This method is not intended for evaluation of
surfaces designed for exterior applications or uncoated sur-
3. Terminology
faces. Use of this test method for evaluating exterior perfor-
mancehasnotbeenvalidated,norhavethelimitationsforsuch 3.1 Definitions—For definitions of terms refer to Terminol-
ogy D16.
use been determined.
1.5 The values stated in either SI units or inch-pound units 3.2 Definitions of Terms Specific to This Standard:
3.2.1 chamber control, n—openPetridishcontainingappro-
are to be regarded separately as standard. The values stated in
each system may not be exact equivalents; therefore, each priate agar to demonstrate viability of fungal organisms within
the environmental chamber.
system shall be used independently of the other. Combining
values from the two systems may result in non-conformance
3.2.2 coated building product, n—a building material hav-
with the standard.
ingaliquid,liquefiableormasticcompositionthatisconverted
1.6 This standard does not purport to address all of the to a solid protective, decorative, or functional adherent film
after application as a thin layer onto a building fabric.
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro-
3.2.3 interior, n—any surface not exposed to exterior envi-
priate safety, health, and environmental practices and deter-
ronments in end use.
mine the applicability of regulatory limitations prior to use.
3.2.4 interior finish, n—interior wall and ceiling finish and
interior floor finish.
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 D01.28 on Biodeterioration. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Nov. 1, 2021. Published November 2021. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 2013. Last previous edition approved in 2017 as D7855/D7855M–13 Standards volume information, refer to the standard’s Document Summary page on
(2017). DOI: 10.1520/D7855_D7855M-13R21. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7855/D7855M − 13 (2021)
3.2.5 material control, n—untreated representative sub- nineteenlitercontainermeasuringapproximately460mmlong
strate. 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
3.2.6 sample, n—a portion of material taken from a larger
in.] test specimens suspended from rods using cable ties.
quantity for the purpose of estimating properties or composi-
Opaque chambers shall have a viewing port that permits
tion of the larger quantity.
observation of chamber controls. Chamber shall permit tem-
3.2.7 sample tests, n—a group of samples (one or more).
perature and humidity monitoring without opening the cham-
3.2.8 test run, n—theevaluationofcoatedbuildingproducts
ber lid. Examples would include wireless or wired probes.
in accordance with the procedure outlined in this test method.
7.1.1 The test chamber shall be designed so that no conden-
3.2.9 test specimen, n—a portion of a test unit needed to sate forming on the top interior surface will drip onto the test
specimens. For stand-alone chambers, this can be accom-
obtain a single test determination.
plished by designing the top so that the interior surface is at an
4. Summary of Test Method
angle of at least 30 degrees, relative to the plane of the bottom
of the chamber. A sheet of polycarbonate secured at an angle,
4.1 This test method is an indirect inoculation to a coated
or hinged or joined sheets of polycarbonate attached to the
interior building product of two fungal organisms, Aspergillus
underside of the lid will direct the condensation away from the
nigerand Penicillium citrinum.Testspecimensareplacedinan
test samples. Condensation inside the test chamber is not a
environmentalchambermaintainedat30 62°C[86 63.6°F]
concern as it indicates that humidity is being maintained.
and at greater than 90 % relative humidity for four weeks.
7.1.1.1 Anon-corrosive open grid is placed at the bottom of
Humidity is maintained by adding sufficient sterile DI water to
the test chamber above the water level supporting 100 by 15
the bottom of the covered test chamber. A continuous fungal
mm [4 by ⁄8 in.] sterile Petri dishes alternating the two fungal
inoculation is provided by open Petri dishes supporting seven
organisms. See Fig. 1 for non-corroding open grid example.
day cultures of the two test organisms placed on a rack below
Place sufficient Petri dishes on the rack to fill the grid. The
the test pieces. Test specimens are removed from the chamber
plastic grid designed to cover recessed ceiling fixtures or
after four weeks exposure and examined for fungal growth.
similar works well.
The evaluation is a macroscopic inspection of the test pieces
7.1.1.2 Position test specimens by suspending them from
with indirect lighting.
rodsusingplasticcableties.Samplesmustbe50to100mm[2
5. Significance and Use to 4 in.] above the inoculated Petri dishes. The minimum
distance between adjacent specimens and between test speci-
5.1 An accelerated test for determining the resistance of
mens and chamber walls shall be at least 25 mm [1 in.].
interior coated building products to mold growth is useful in
Materials used as the rods or mounting racks shall be non-
estimating the relative performance for use in interior environ-
corroding and of sufficient strength to support specimens
ments under conditions favorable to fungal growth.
throughout the duration of the test. Use of engineered plastics
5.2 Static or environmental chambers provide controlled
such as polycarbonate has been found suitable. Fig. 2 shows a
laboratory micro-environment conditions. These chambers are
photo of typical chamber construction. Fig. 3 illustrates use of
not intended to duplicate room conditions, and care must be
cable ties to hang test specimens from rods.
taken when interpreting the results. Static chambers are not a
7.2 Measurement Instruments, capable of accurate and pre-
substitute for dynamic chambers or field studies.
cise measures of temperature and humidity. See Section 12.
6. Interferences
6.1 Proper lab ventilation, hygiene, and aseptic technique
must be followed to ensure fungal cultures are pure and no
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 62°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
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 (2021)
8.2 Chamber Controls—Open PDA plates placed on the
bottom of the chamber at opposite corners and near the center.
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
FIG. 2 Typical Environment Chamber Set Up
laboratories specially equipped for conducting microbiological
tests.
10. Sampling and Test Specimens
10.1 Sampling shall be representative of the product being
evaluated.
10.2 Test Specimens:
10.2.1 Aminimumofthreetestspecimensshallbecutfrom
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
FIG. 3 Cable Ties used to Hang Test Specimens from Rods Inside
use. Add approximately 25 mm [1 in.] of water to the bottom
of the Environmental Chamber
of the container. Ensure the water level is sufficient to provide
humidity through the duration of the test. If the test specimens
absorb the water or water is lost through the seal of the lid,
7.3 Incubator or Controlled Temperature Room maintained
additional water must be added to ensure the relative humidity
at 30 6 2°C [86 6 3.6°F].
remains at 90 % or greater for the duration of the test. The
8. Reagents and Materials
water level should be at least 25 mm [1 in.] below the rack
supporting the Petri dishes of the fungal test organisms.
8.1 Cultures—Aspergillus niger,ATCC 6275 or IMI/CABI
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
temperaturecontrolledchambersetat30 62°C[86 63.6°F]
buildingproductsbeingtested.Theorganismsnamedin8.1are
to equilibrate for 24 h before starting the test. Record the
notrepresentativeofallpotentialfungalorganismsthatmaybe
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
fungalorganismsmayalsobeusedinseparateevaluations,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
newtestpieces.Temperatureandhumiditymeasurementsshall
potential for interferences between non-specified fungal test
be included in the final report.
organisms shall be considered when using organisms other
11.3 Prepare spore suspensions of each test fungi from 7 to
than those named in 8.1.
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
Penicillium citrinum typically takes longer to sporulate than
8.1 as appropriate.
Aspergillus niger so cultivation should begin earlier assuring
both orga
...