1、Designation: D3273 121Standard 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.1NOTEEditorial cor
3、rections were made in paragraphs 4.2.1 and 4.2.2 in December 2015.1. Scope1.1 This test 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 in
4、terior environment.The apparatus is designed so it can be easily built or obtained2by 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. Performa
5、nce at a certain rating does not imply anyspecific period of time for a fungal free coating. 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
6、this testmethod for evaluating exterior coatings performance has not beenvalidated, nor 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 t
7、he scope of this test method must be included. Any acceleratedweathering (leaching, weathering 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 with
8、in the relatively narrow limits specified in order forthe chamber to function reproducibly 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
9、6 2F ) is necessary for test panels to develop rapidly andmaintain an adequate moisture 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 thesa
10、fety concerns, if any, associated with its use. It is theresponsibility of the user of 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 T
11、erms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory 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 coatin
12、gs designed for use in interior environ-ments that promote mold growth and in evaluating 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
13、Environmental Chamber, capable of maintaining a rela-tive humidity of 95 6 3 % at a temperature 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 f
14、rom the cabinet is insignificant and that 92 to 98 %relative humidity is readily obtained at the test temperature.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 Biod
15、eterioration.Current edition approved Feb. 1, 2012. Published March 2012. Originallyapproved in 1973. Last previous edition approved in 2005 as D3273 00 (2006).DOI: 10.1520/D3273-12E01.2Additional specifications for construction of a chamber that has been foundsuitable for this method may be obtaine
16、d from 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 AST
17、M website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1Alternatively the cabinet must be insulated with suitablematerials to minimize heat loss.4.2 Cabinet, suitable to accommodate the desired number oftest panels, typically a mini
18、mum of twenty-five 75 by 100-mm(3 by 4-in.) panels under these test conditions can be con-structed as follows (Fig. 1):4.2.1 Tank, polypropylene or polyethylene or gas, 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
19、in.). A pitched top with straight sides should beconstructed out of acrylic plastic so moisture 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 ismaintaine
20、d at 32.5 6 1C (90 6 2F) which prevents conden-sation on the interior panel surfaces.4.2.2 Heating Coil,5,6installed in the bottom of the cham-ber by water tight connections through the end wall. The heatershould be sized to allow reasonable recovery time and uniformheating of the water when the cha
21、mber is opened and closed toplace or inspect samples.7It is so placed that it is immersedwhen there 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 2
22、F) . The temperature in thechamber should be monitored and controlled by placing asuitable thermocouple or RTD8in an area near the test panels.The temperature can be displayed and controlled by a solidstate proportional controller.94.2.3 Tray, stainless steel, aluminum or plastic, approxi-mately 25
23、mm (1 in.) smaller than the inside dimensions of thechamber and 25 to 75 mm (1 to 3 in.) deep with a non-corrodible metal10mesh bottom should be supported 25 mm (1in.) above the water level and centered in the chamber. Onelayer of fine plastic or fiberglass screen may be placed over themetal mesh, i
24、f 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 across the width of the chamber at a heightand spacing
25、 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, plastic cable ties or a large clip is used with thegyps
26、um 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.4.3 Psychrometer, for measuring relative humidity in thetest area. A temperature/humidity datalogger may also be usedif the accuracy of the relative hum
27、idity 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 fall from 5.5 to 7.0. Do not allowsoil to become compacted. Additional peat moss can be addedto lower the pH int
28、o the required range.5.2 Cultures:4Tanks of this type available in dimensions approximating 69 by 46 by 46 cm(27 by 18 by 18 in. ) are available from laboratory supply companies. Nalgene tankshave been found suitable.5The sole source of supply of a78-mm (0.315-in.) diameter inconel sheathedheater, M
29、odel STRI (STRI-1248/120), known to the committee at this time isOmega Engineering, Inc., One Omega Drive, Stamford, CT 06907, www.omega-.com.6Complete units may also be purchased through New Jersey Industrial Controls.7For a 46 by 46 by 61-cm (18 by 18 by 24-in.) tank, a 250-watt heater isrecommend
30、ed. For a 61 by 61 by 91-mm (24 by 24 by 36-in.) tank, an 800-wattheater is recommended.8A grounded 1.5 mm (116) or 2.4 mm (332-in.) “J” type stainless thermocouplegives good response for this application.9A Eurotherm Model 91 controlling the heater via solid state relay hasdemonstrated that it can
31、be calibrated and provide calibratable, accurate, and reliableperformance.10150-mesh 316 stainless screen gives a high percentage of open area and willnot allow dirt to contaminate the water.FIG. 1 Environmental Cabinet AssemblyD3273 12125.2.1 Aureobasidium pullulans,6,11ATCC 93485.2.2 Aspergillus n
32、iger,6,11ATCC 62755.2.3 Penicillium,6,11Sp. 12667 or ATCC 98495.3 Test Panels:5.3.1 Ponderosa Pine (Pinus ponderosa Laws) SapwoodPanels, approximately 13 mm (12 in.) thick, 75 by 100 mm (3by 4 in.), free of excessive resins, knots, growth rings or otherabnormalities, surfaced smooth on four sides. W
33、ood shall bekiln dried after sawing to avoid infestation of wood-rottingfungi, and any wood showing evidence of such infestation shallbe eliminated as test material. Wood shall be weighed afterconditioning at room temperature in a dry room to 15 %moisture content. Calculated weight shall fall betwee
34、n 365 and425 kg/m3(6.0 and 7.0 g/in.3). Panels containing heartwoodareas should not be used as they will inhibit mold growth undertest 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, Glas
35、s, 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), useanother typ
36、e 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 specifi
37、ed mold suspensions.6.2 Prepare mold slants of all three cultures and incubate 10to 14 days. Prepare mold suspensions from each type of moldslant by the following procedure: Add one drop of 25 %nonionic surfactant12solution to 95 to 100 mL sterile deionizedor distilled water and gently mix. Pipet 5
38、mL of this solutiononto each of the mold slants. Scrub the surface of the slant witha sterile cotton swab or sterile glass rod to remove as muchspore and mycelial growth as possible without digging up thesurface of the agar. Pour the water from the scrubbed slant backinto the surfactant-sterile wate
39、r mixture for dilution. Shakegently for 15 to 20 min to break up clumps of mold. Use a pipetto distribute the mold suspensions evenly over the surface ofthe greenhouse soil in the tray in the cabinet.6.3 Allow two weeks of continuous operation for the moldto sporulate and equilibrate with the enviro
40、nment beforestarting a test. It should not be necessary to continuallyre-inoculate the chamber soil after sufficient microorganismgrowth has been established. If the chamber is maintained incontinuous operation, a tray of soil can produce mold sporesfor many months, but should be replaced with a fre
41、sh inocu-lated soil twice per year.6.4 Viability of the mold growth in the cabinet can bechecked by placing several malt agar or potato dextrose agarplates,13open and face up, at several locations on the panelsupport rods. After 1 h, cover plates and place in incubator at32.5 6 1C (90 6 2F) for 5 to
42、 7 days. If an incubator is notavailable, leave the covered plates in the cabinet. Mold growthshould be medium-heavy to heavy and cover the completesurface of the agar plate.7. Procedure7.1 Preparation of Test PanelsWear disposable plastic orequivalent gloves or utilize other techniques when handlin
43、gpanels 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 or as specified by the coatingmanufacturer, allowing 1 day between coats unless othe
44、rwisespecified. 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 before placing in the test chamberfor start of environmental exposure. Test pieces
45、 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 sufficient spacing to allow free circulation ofair and to prevent contact between panel
46、s 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 mildew growth, in all tests. If the cabinet is operatingproperly, unpainted panels sh
47、ould 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 growth each week for4 weeks ona0to10rating scale by estimating the percentageof surfa
48、ce defacement with 10 being no defacement and 0being completely defaced. Test panels and controls should bepicked up and examined under good light. Use the drawings inFigs. 2-11 as a guide for the rating scale. A grid has beensuperimposed on each panel to assist in the fungal growthestimates. Record
49、 the temperature and relative humidity eachweek when the chamber is opened to confirm the targetparameters are being achieved.11The sole source of supply of the cultures can be obtained from American TypeCulture Collection, P.O. Box 1549, Manassas, VA 20108. Cultures can be main-tained on malt agar or potato dextrose agar. Prepared slants can be obtained frommicrobiological supply companies.12Octyl phenol ethoxylates, 910 mole EO, have been found suitable.13Prepared agar plates are available from microbiological supply companies.D3273 1213Ratings:
