ASTM D7584-10

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Designation: D7584 − 10
StandardTest Method for
Evaluating the Resistance of the Surface of Wet Blue to the
Growth of Fungi in an Environmental Chamber
This standard is issued under the fixed designation D7584; 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 3.1.1 wet blue—hide or skin, or split of a hide or skin,
tanned with basic chromium sulfate, containing approximately
1.1 This environmental chamber method measures the re-
50% moisture and an acidic pH.
sistanceofthetreatedwetbluetothegerminationofsporesand
subsequentvegetativegrowthoveraperiodoffourweeks.The
3.1.2 fungi—chemoorganotrophic eukaryotic organisms liv-
test method is useful in estimating the performance of fungi- ing mainly under aerobic conditions and generating energy by
cides and should assist in the prediction of storage time of wet the oxidation of organic materials.
bluebeforefungalgrowthbegins.Theapparatusisdesignedso
3.1.3 mold—a macroscopic discoloration of the surface of
it can be easily built or obtained by any interested party and
wet blue. Mold also a sign of the presence of microscopic
duplicate the natural environment in which wet blue is inocu-
fungal growth in the form of usually clear to white fungal
latedwithfungalspores.Sporesthatgerminateonuntreatedor
hyphae, spores of various colors, and other structures. Colored
treated wet blue can produce fungal growth, resulting in
spots, probably due to the presence of a colored pigment
disfigurement or discoloration, or both, of the wet blue.
produced by the fungus, have been observed on the surface of
1.2 The values stated in SI units are to be regarded as wet blue in places where fungal growth has occurred and then
standard. No other units of measurement are included in this stopped. Fungal structures such as hyphae and spores may be
standard. viewed by simply using a 10× hand lens.
1.3 This standard does not purport to address all of the
3.1.4 Fungi of Importance in the Tannery:
safety concerns, if any, associated with its use. It is the
3.1.4.1 Filamentous Fungi:
responsibility of the user of this standard to establish appro-
(1)A wide variety of fungi have been identified in the
priate safety and health practices and determine the applica-
tannery, but commonly encountered species include Aspergil-
bility of regulatory limitations prior to use.
lus spp., Paecilomyces spp., and Penicillium spp.
(2)Aspergillus niger produces black spores and Penicil-
2. Referenced Documents
lium luteum produces yellow-green colored spores.
2.1 ASTM Standards:
(3)Trichoderma viride produces green spores.
D3273TestMethodforResistancetoGrowthofMoldonthe
3.1.4.2 Yeast—Many yeasts are cream colored, but pig-
Surface of Interior Coatings in an Environmental Cham-
mented ones may also be encountered including Rhodotorula
ber
spp. which is pigmented red.
E177Practice for Use of the Terms Precision and Bias in
3.1.4.3 Factors Favoring the Growth of Fungi in the Tan-
ASTM Test Methods
nery:
E691Practice for Conducting an Interlaboratory Study to
(1)Wetbluecontainsnutrientsbeneficialtofungalgrowth.
Determine the Precision of a Test Method
(2)Favorable environmental factors include a slightly
acidic pH, a high moisture content, and warm temperatures.
3. Terminology
(3)Fungal spores are transported by air or on hides and
3.1 Definitions: skins into the tannery and distributed within the tannery by
physical contact or air currents to favorable substrates for
growth including wet blue.
ThistestmethodisunderthejurisdictionofASTMCommitteeD31onLeather
and is the direct responsibility of Subcommittee D31.02 on Wet Blue.
4. Personal Protective Equipment
Current edition approved May 1, 2010. Published June 2010. DOI: 10.1520/
D7584-10.
4.1 Fungi are opportunistic organisms. For this reason,
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
rubber gloves or powder-free latex examination gloves, safety
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
glasses, and a laboratory coat should be worn whenever
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. handling samples with fungal growth are encountered.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7584 − 10
FIG. 1 Environmental Chamber
4.2 Adust mask or respirator should be worn whenever the 6. Significance and Use
environmental chamber is open or whenever samples with
6.1 The environmental chamber method is an accelerated
fungal growth are encountered.
test for determining the resistance of wet blue to the growth of
4.2.1 Dust Mask—Examples, 3M 8210 and 3M 9322 Res-
3,4
fungi, the causal agent of mold. See Test Method D3273.
pirators.
6.2 Theenvironmentalchambermethodisusefulinestimat-
4.2.2 Half-Mask Respirator—Equipped with a filter ap-
ing the performance of fungicides and should assist in the
proved 99.97% efficient against solid or liquid particulates
prediction of storage time before fungal growth begins.
including oil-based particles: For example, the North 7700
Series Half-Mask Respirator equipped with Cartridge PI 00
6.3 Theenvironmentalchambermethodduplicatesthenatu-
Filter.
ral environment in which wet blue is inoculated with fungal
spores and subsequently disfigured or discolored by fungi.
5. Summary of Method of Evaluation
6.4 The environmental chamber method measures the resis-
5.1 Wet blue is suspended in a chamber with a warm, moist
tance of the treated wet blue to the germination of spores and
environment.
subsequent vegetative growth that spreads over the surface of
5.2 After incubation for seven days, the entire surface area a comparatively large wet blue specimen over a period of four
of the grain and flesh sides of the test specimen are examined weeks.
visually,firstoneside,forexample,thegrainside,andthenthe
6.5 Theenvironmentalchambercanbekeptinoculatedwith
other, for example, the flesh side, for the presence of fungal
fungi representative of those found in tanneries by adding
growth and rated using a numerical scale from 10 (clean or
samples of wet blue with fungal growth currently operating
withoutanysignoffungalgrowth)to0(completelycoveredby
tanneries.
fungal growth).
5.3 StepBisrepeatedonceperweekuntilratingshavebeen
completed for all samples at 14, 21, and 28 days of environ-
Didato, Dean T., Bowen, Judith R., and Hurlow, Elton L., Microorganism
mental chamber exposure.
Control During Leather Manufacture, Leather Technologists Pocket Book, Chapter
20, Editor M. K. Leafe, The Society of Leather Technologists and Chemists,
5.4 Afterthefourthweeklyreadingiscompleted,areportof
Withernsea, East Yorkshire, UK, 1999.
theresultsispreparedanddeliveredtothepartyrequestingthe
Leather Technologists Pocket Book, The Society of Leather Technologists and
evaluation. Chemists, Withernsea, East Yorkshire, UK, 1999, pp. 405.
D7584 − 10
6.6 Control specimens of wet blue without fungicide treat- entering the laboratory and maintaining separate rooms for
ment can be added to the chamber periodically to increase initial handling of new samples for testing and a clean room to
levels of fungal growth in the chamber. house the environmental chamber.
7.1.2 Fungus Gnats (Sciaroidea—including the dark winged
6.7 Leaching of fungicide from the test specimen into the
fungus flies, Sciaridae):
agar often causes a zone of inhibition of fungal growth in the
7.1.2.1 Larvae of fungus gnats are known to live wherever
Petri dish test, but in the environmental chamber any leaching
fungi grow.
of fungicide from the test specimen drips into the water
7.1.2.2 The same general hygiene and preventive precau-
contained in the chamber and thus does not cause the types of
tions that are used to control mites apply to the control of
false readings observed in the Petri dish test.
fungus gnats, especially keeping the room containing the
environmental chambers clean.
7. Interferences
7.1.3 Ifculturemitesorfungusmitesbecomeestablishedin
7.1 Acommon interference is contamination of samples by
anenvironmentalchamber,terminateworkinprogress,remove
unwanted organisms, for example arthropods—including cul-
all samples and soil, disinfect all hard surfaces, and begin the
ture mites and fungus gnats—that enter the environmental
chamber startup process again.
chamberontestspecimensorfromthelaboratoryenvironment.
7.2 Limit the sunlight entering the chamber room and only
7.1.1 Culture Mites (Acari including Tyroglyphus and Tar-
have room lights on when working in the room to prevent the
sonemus):
growth of algae.
7.1.1.1 Culture mites invade the environmental chamber
eating the funga hyphae on the test specimens, infecting them
8. Apparatus (see Figs. 1 and 2)
with bacteria, and moving from one test specimen to another
contaminating them.
8.1 Atypical environmental chamber will have the follow-
7.1.1.2 Mites thrive in environments with high temperature ing components (all measurements rounded to the nearest
and humidity.
7.1.1.3 Mites are attracted by the odor of fungi and can be
The sole source of supply of the complete chamber known to the committee at
also be brought into the environmental chamber on the bodies
this time is Indelco Custom Products, 32 Flicker St., Memphis, TN 38182-0183. If
of flies, organic material, soil, and even test specimens.
you are aware of alternative suppliers, please provide this information to ASTM
7.1.1.4 Generalhygieneandpreventiveprecautionsmustbe
International Headquarters. Your comments will receive careful consideration at a
taken to control mites, including examining all new materials
meeting of the responsible technical committee, which you may attend.
FIG. 2 Environmental Chamber Diagram
D7584 − 10
whole centimeter and may vary in dimensions from one
chamber design to another):
8.1.1 The chamber is raised above floor level, made mobile
by setting it on a steel platform with casters, and built strong
enough to support the weight of the chamber, soil, water, and
samples.Atypicalplatformmeasures97cminlengthby66cm
in width and height with steel legs and casters that elevate the
chamber an additional 36 cm above the floor.
8.1.2 Arectangularshapedtankisusedtocontainthewater,
soil, and samples.
8.1.2.1 Atypicaltankmeasures94cminlengthby62cmin
width by 62 cm in height with a wall thickness of l cm. The
tankisbuilttobewatertight.Theinsidedimensionsofthetank
are 91 cm in length by 61 cm in width and height. The water
level in the bottom of the tank is maintained at a height of 8 to
FIG. 4 Soil Tray
17 cm.
8.1.2.2 The tank has an offset shoulder at the top rim. This
serves to support the chamber cover when in the closed
position,tocontainwaterdrippingfromthechambercoverand
to divert the water back to the bottom of the tank without
dripping on the wet blue samples. The rim gives the top of the
tank an extended length of 104 cm, an extended width of 72
cm,andaraisedoutsidewallof3.8cminheight.Theinsideof
the rim drops 3.6 cm below the surface of the top of the tank
to a horizontal shelf measuring 5 cm in width with a curving
waterfall that diverts water toward the bottom of the tank.
8.1.3 Arectangular shaped soil tray is used to hold the soil
mix and inoculum. See Figs. 3 and 4.
8.1.3.1 The soil tray is seated on top of a table for the
purpose of elevating the tray above the level of the water.
8.1.3.2 The dimensions of the soil tray are 82 cm in length
by 56 cm in width by 5 cm in height.
FIG. 5 Chamber with Rods
8.1.3.3 The bottom of the tray consists of a sheet of
corrosion-resistant metal mesh. One layer of plastic or fiber-
samples. Chambers may be designed to provide space for
glass screening may be placed over the metal mesh to hold the
exposureofgreaternumbersofsamplestosuittheneedsofthe
soil in place if necessary.
testing laboratory.
8.1.3.4 The primary purpose of the soil tray is to help keep
8.1.4.1 The frame measures 90 cm in length by 58 cm in
the chamber evenly moist.
width by 8 cm in height and is 2 cm in thickness.
8.1.4 Arectangular shaped supporting frame is located near
8.1.4.2 Four L-shaped brackets hold the frame in place, and
the top of the chamber and serves to hold the rods from which
each bracket measures 5 cm in length by 2 cm in width by 0.6
the wet blue samples hang. See Fig. 5. This particular frame
cm in thickness on each side. The brackets are fastened to the
will provide enough rod space to hang 100 or more wet blue
chamber wall using stainless steel fittings.
8.1.4.3 The top side of the frame on both sides of the
chamber running the length of the chamber has U-shaped
valleys cut into the top side to hold the rods in place and at a
right angle to the sides of the chamber. The U-shaped valleys
are cut to a maximum depth of 0.6 cm and a width of 1.1 cm.
8.1.4.4 The rods measure 57 cm in length and 1.2 cm in
diameter. Ten rods holding 10 to 15 wet blue samples hung at
right angles to the rod can easily be accommodated in the
chamber. As an alternative to using rods to hang the samples
on, use a wire strung across the top of the chamber.
8.1.4.5 Plastic insulated solid copper wire of 14 gauge (3
mm diameter) is useful in making hangers for wet blue
samples. The wire is bendable into a suitable “S” shape for
hanging test samples and retains its shape for multiple uses.
8.1.5 The top of the environmental chamber is constructed
FIG. 3 Rectangular Shaped Soil Tray of acrylic plastic and is designed to have straight sides and a
D7584 − 10
pitched top so that moisture condensation will run down the
sides and be recirculated instead of dripping onto the wet blue
samples. The top features a handle at the front, hinges at the
rear, and support struts on each side to allow the lid to be
propped in the open position. Typical dimensions include:
8.1.5.1 Sides—Two sheets of acrylic cut to 99 cm at base
witha6cm vertical rise and then at an angle of 40 degrees for
64 cm on each side to the peak.
8.1.5.2 Front and Rear—Bottom sheet 69 cm wide by 6 cm
on sides rising vertically and attaching to a sheet rising at an
angleof40degreesmeasuring69cmwideby64cminlength.
8.1.5.3 The handle is mounted on the front sheet. The base
of the handle measures 3 cm in thickness by 3 cm in width by
30 cm in length and is used to attach the handle (30 cm in
length by 5 cm in width by 1 cm in thickness).
8.1.5.4 Singleordoublesupportstrutsareusedandmeasure
FIG.
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