1、Designation: D3273 16Standard Test Method forResistance to Growth of Mold on the Surface of InteriorCoatings in an Environmental Chamber1This standard is issued under the fixed designation D3273; the number immediately following the designation indicates the year oforiginal adoption or, in the case
2、of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 This te
3、st method describes a small environmental cham-ber and the conditions of operation to evaluate reproducibly ina 4-week period the relative resistance of paint films to surfacemold fungi, mildew growth in a severe interior environment.The apparatus is designed so it can be easily built or obtained2by
4、 any interested party and will duplicate results obtained in alarge tropical chamber.1.2 This test method can be used to evaluate the compara-tive resistance of interior coating to accelerated mildewgrowth. Performance at a certain rating does not imply anyspecific period of time for a fungal free c
5、oating. However, abetter rated coating nearly always performs better in actual enduse.NOTE 1This test method is intended for the accelerated evaluation ofan interior coatings resistance to fungal defacement. Use of this testmethod for evaluating exterior coatings performance has not beenvalidated, n
6、or have the limitations for such use been determined. If thistest method is to be used for the testing of an exterior coating system, aprecautionary statement regarding interpretation of results as beingoutside of the scope of this test method must be included. Any acceleratedweathering (leaching, w
7、eathering machine exposure, etc.) should bereported and should also bear reference to the fact that it is beyond thecurrent scope of this test method.1.3 Temperature and humidity must be effectively con-trolled within the relatively narrow limits specified in order forthe chamber to function reprodu
8、cibly during the short testperiod. Severity and rate of mold growth on a film is a functionof the moisture content of both the film and the substrate. Arelative humidity of 95 6 3 % at a temperature of 32.5 6 1C(90 6 2F ) is necessary for test panels to develop rapidly andmaintain an adequate moistu
9、re level to support mold growth.1.4 The values stated in SI units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user o
10、f this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:3E177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlabor
11、atory Study toDetermine the Precision of a Test Method3. Significance and Use3.1 An accelerated test for determining the resistance ofinterior coatings to mold growth is useful in estimating theperformance of coatings designed for use in interior environ-ments that promote mold growth and in evaluat
12、ing compoundsthat may inhibit such growth and the aggregate levels for theiruse (see also Note 1).3.2 This test method should preferably be used by personswho have had basic microbiological training.4. Apparatus4.1 Environmental Chamber, capable of maintaining a rela-tive humidity of 95 6 3 % at a t
13、emperature of 32.5 6 1C (906 2F) while providing a continuous inoculation of the surfaceof exposed panels with mold spores. The chamber should bekept in a room controlled to no less than 21C (75F) so thatheat loss from the cabinet is insignificant and that 92 to 98 %relative humidity is readily obta
14、ined at the test temperature.Alternatively the cabinet must be insulated with suitablematerials to minimize heat loss.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.28 on
15、Biodeterioration.Current edition approved June 1, 2016. Published July 2016. Originally approvedin 1973. Last previous edition approved in 2012 as D3273 121. DOI: 10.1520/D3273-16.2Additional specifications for construction of a chamber that has been foundsuitable for this method may be obtained fro
16、m New Jersey Industrial Controls, P.O.Box 601, Rockaway, NJ 07866.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM web
17、site.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2 Cabinet, suitable to accommodate the desired number oftest panels, typically a minimum of twenty-five 75 by 100-mm(3 by 4-in.) panels under these test conditions can be con-stru
18、cted as follows (Fig. 1):4.2.1 Tank, polypropylene or polyethylene or glass, with anoffset shoulder at the top rim is used as the chamber.4Theminimum recommended tank size is 46 by 46 by 61 cm (18 by18 by 24 in.). A pitched top with straight sides should beconstructed out of acrylic plastic so moist
19、ure condensation willrun down the sides and be recirculated instead of dripping ontothe panels. A pitched top is not necessary if the chamber isincubated in a temperature-controlled warm room that ismaintained at 32.5 6 1C (90 6 2F) which prevents conden-sation on the interior panel surfaces.4.2.2 H
20、eating Coil,5,installed in the bottom of the chamberby water tight connections through the end wall. The heatershould be sized to allow reasonable recovery time and uniformheating of the water when the chamber is opened and closed toplace or inspect samples.6It is so placed that it is immersedwhen t
21、here are 50 to 75 mm (2 to 3 in.) of water in the bottomof the chamber. A heating coil is not necessary if the chamberis incubated in a temperature-controlled warm room that ismaintained at 32.5 6 1C(906 2F) . The temperature in thechamber should be monitored and controlled by placing asuitable ther
22、mocouple or RTD7in an area near the test panels.The temperature can be displayed and controlled by a solidstate proportional controller.8The heating coil is not necessaryif the chamber is incubated in a temperature-controlled warmroom that is maintained at 32.5 6 1C (90 6 2F).4.2.3 Soil Tray, stainl
23、ess steel, aluminum or plastic, approxi-mately 25 mm (1 in.) smaller than the inside dimensions of thechamber and 25 to 75 mm (1 to 3 in.) deep with a non-corrodible metal9mesh bottom should be supported 25 mm (1in.) above the water level and centered in the chamber. Onelayer of fine plastic or fibe
24、rglass screen may be placed over themetal mesh, if needed for holding soil.NOTE 2It has been found that eliminating the plastic screen helpsimprove water vapor transfer into soil, and maintain active fungal cultures.4.2.4 Series of Wood, Glass, or Fiberglass Reinforced Plas-tic Bars, suspended acros
25、s the width of the chamber at a heightand spacing that allows the use of test panels 75 by 100 mm (3by 4 in.), hung vertically, with approximately 75-mm (3-in.)clearance above the inoculated soil with a suitable method offastening. Screw eyes are used with the wooden panels while awire frame, plasti
26、c cable ties or a large clip is used with thegypsum board panels. Other support systems may be utilized.NOTE 3Other angles of exposure may be used but may alter the rateand severity of mold growth. This change of positioning must be includedin the final report.4.3 Psychrometer, for measuring relativ
27、e humidity in thetest area. A temperature/humidity datalogger may also be usedif the accuracy of the relative humidity sensor is 63%.5. Reagents and Materials5.1 SoilA good quality greenhouse-grade potting soil,suitable for plant propagation, containing 25 % peat moss. ThepH range of the soil should
28、 fall from 5.5 to 7.0. Do not allowsoil to become compacted. Additional peat moss can be addedto lower the pH into the required range.5.2 Cultures:5.2.1 Aureobasidium pullulans,10ATCC 9348.4Tanks of this type available in dimensions approximating 69 by 46 by 46 cm(27 by 18 by 18 in. ) are available
29、from laboratory supply companies. Nalgene tankshave been found suitable.5The sole source of supply of a78-mm (0.315-in.) diameter inconel sheathedheater, Model STRI (STRI-1248/120), known to the committee at this time isOmega Engineering, Inc., One Omega Drive, Stamford, CT 06907, www.omega-.com.6Fo
30、r a 46 by 46 by 61-cm (18 by 18 by 24-in.) tank, a 250-watt heater isrecommended. For a 61 by 61 by 91-mm (24 by 24 by 36-in.) tank, an 800-wattheater is recommended.7A grounded 1.5 mm (116) or 2.4 mm (332-in.) “J” type stainless thermocouplegives good response for this application.8A Eurotherm Mode
31、l 91 controlling the heater via solid state relay hasdemonstrated that it can be calibrated and provide calibratable, accurate, and reliableperformance.9150-mesh 316 stainless screen gives a high percentage of open area and will notallow dirt to contaminate the water.10Cultures can be obtained from
32、American Type Culture Collection, P.O. Box1549, Manassas, VA 20108. Cultures can be maintained on malt agar or potatodextrose agar. Prepared slants can be obtained from microbiological supplycompanies.FIG. 1 Environmental Cabinet AssemblyD3273 1625.2.2 Aspergillus niger,10ATCC 6275.5.2.3 Penicillium
33、 sp,1012667 or ATCC 9849.5.3 Test Panels:5.3.1 Softwood Sapwood, such as Ponderosa Pine (Pinusponderosa Laws) Sapwood Panels, approximately 13 mm (12in.) thick, 75 by 100 mm (3 by 4 in.), free of excessive resins,knots, growth rings or other abnormalities, surfaced smooth onfour sides. Wood shall be
34、 kiln dried after sawing to avoidinfestation of wood-rotting fungi, and any wood showingevidence of infestation such as blue stain shall be eliminated astest material. Wood shall be weighed after conditioning at roomtemperature in a dry room to 15 % moisture content. Calcu-lated weight shall fall be
35、tween 365 and 425 kg/m3(6.0 and 7.0g/in.3). Panels containing heartwood areas should not be usedas they will inhibit mold growth under test conditions.5.3.2 Gypsum Board Panels, 13 to 25 mm (12 to 1 in.) thick,75 by 100 mm (3 by 4 in.).5.3.3 Other Substrates such as Drawdown Paper, TongueDepressors,
36、 Glass, etc., may be used as agreed upon by theparties involved. However, when comparing the relative per-formance of various coatings, the substrates must be the samein order for the results to be meaningful. When using substratesthat are not themselves susceptible to attack (like glass), useanothe
37、r type of positive growth control rather than the un-coated panel as specified in 7.2.6. Preparation of Apparatus6.1 Place greenhouse soil in the tray in the cabinet and addwater to the tank chamber to the desired depth. Allow thecabinet to equilibrate for 24 h before inoculating the soil withthe sp
38、ecified mold suspensions.6.2 Prepare fungus plates or slants of all three cultures andincubate 10 to 14 days. Prepare suspensions from each fungusby the following procedure: Add one drop of 25 % nonionicsurfactant11solution to 95 to 100 mL sterile deionized ordistilled water and gently mix. Dispense
39、 5 to 10 mL of thissolution onto each of the fungus cultures. Scrub the surface ofthe slant with a sterile cotton swab or sterile glass rod toremove as much spore and mycelial growth as possible withoutdigging up the surface of the agar. Pour the water from thescrubbed slant back into the surfactant
40、-sterile water mixture fordilution. If necessary, shake gently to break up clumps ofspores. Distribute the fungal suspensions evenly over thesurface of the greenhouse soil in the tray in the cabinet.6.3 Before starting a test, verify the readiness of the soil byhaving untreated controls achieve a ra
41、ting of 4 to 6 within 2 to3 weeks of being placed in the chamber. It should not benecessary to continually re-inoculate the chamber soil aftersufficient microorganism growth has been established. If thechamber is maintained in continuous operation, a tray of soilcan produce mold spores for many mont
42、hs, but should bereplaced with a fresh inoculated soil twice per year.6.4 Viability of the mold growth in the cabinet can also bechecked by placing several malt agar or potato dextrose agarplates,12open and face up, at several locations on the panelsupport rods. After 1 h, cover plates and place in
43、incubator at32.5 6 1C (90 6 2F) for 5 to 7 days. If an incubator is notavailable, leave the covered plates in the cabinet. Conforma-tional fungus growth must be that of test organisms, bemedium-heavy to heavy and cover the complete surface of theagar plate.7. Procedure7.1 Preparation of Test PanelsW
44、ear disposable plastic orequivalent gloves or utilize other techniques when handlingpanels to avoid fingerprints. Prepare triplicate panels byapplying two coats of the material under test to both faces andto all edges of the panels at a spreading rate of approximately11 m2/L (450 ft2/gal) per coat o
45、r as specified by the coatingmanufacturer, allowing 1 day between coats unless otherwisespecified. Duplicates may be run instead of triplicates, if agreedupon by parties involved. Condition the panels at 23 6 2C(73.5 6 3.5F) and 50 6 5 % relative humidity for 4 days afterapplication of the last coat
46、 before placing in the test chamberfor start of environmental exposure. Test pieces may also beprepared by the customer and submitted to the laboratory fortesting.7.2 ExposureHang the panels vertically with the bottomapproximately 3 in. (75 mm) above the surface of the inocu-lated soil and with suff
47、icient spacing to allow free circulation ofair and to prevent contact between panels or with wall surfaces.Place replicate panels randomly in the cabinet. Include un-coated control panels, or panels coated with a material knownto fail under the test condition if the substrate is not susceptibleto mi
48、ldew growth, in all tests. If the cabinet is operatingproperly, unpainted panels should developa4to6moldgrowth rating within 2 to 3 weeks. If this growth is notobtained, the cabinet conditions are not satisfactory or there issome interfering treatment on a panel.7.3 RatingRate the panels for mold gr
49、owth each week for4 weeks ona0to10rating scale by estimating the percentageof surface defacement with 10 being no defacement and 0being completely defaced. Include both test and non-test fungalgrowth in the rating. Test panels and controls should be pickedup and examined under good light. Use the drawings in Figs.2-11 as a guide for the rating scale. A grid has been superim-posed on each panel to assist in the fungal growth estimates.Record the temperature and relative humidity each week whenthe chamber is opened to confirm the target parameters arebei
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