1、Designation: D 3273 00 (Reapproved 2005)Standard Test Method forResistance to Growth of Mold on the Surface of InteriorCoatings in an Environmental Chamber1This standard is issued under the fixed designation D 3273; the number immediately following the designation indicates the year oforiginal adopt
2、ion or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the Department of Defense.1.
3、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 interior environment.The apparatus is designed so it can be easily buil
4、t 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. Performance at a certain rating (in accordance withTest Method D 3274) does n
5、ot imply any specific period oftime for a fungal free coating. However, a better rated coatingnearly always performs better in actual end use.NOTE 1This test method is intended for the accelerated evaluation ofan interior coatings resistance to fungal defacement. Use of this testmethod for evaluatin
6、g exterior coatings performance has not beenvalidated, nor have the limitations for such use been determined. Shouldthis test method 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 mu
7、st 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 within the relatively narrow limits
8、 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 to 98 % at a temperature of 32.5 6 1C(90 6 2F ) is necessary for test
9、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 thesafety concerns, if any, associ
10、ated 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 Documents32.1 ASTM Standards:D 3274 Test Method for Evaluating Degree of SurfaceDisfigur
11、ement of Paint Films by Microbial (Fungal orAlgal) Growth or Soil and Dirt Accumulation3. 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 p
12、romote 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 Environmental Chamber, capable of maintaining a rela
13、-tive humidity of 95 to 98 % 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 21 to 24C (70 to 75F) so thatheat loss from the cabinet is insignificant and that 95 to 98
14、%relative humidity is readily obtained 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 respon
15、sibility ofSubcommittee D01.28 on Biodeterioration.Current edition approved Dec. 1, 2005. Published February 2006. Originallyapproved in 1973. Last previous edition approved in 2000 as D 3273 00.2Additional specifications for construction of a chamber that has been foundsuitable for this method may
16、be obtained 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
17、 onthe ASTM website.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 Cabinet, suitable to accommodate the desired number oftest panels typically at least twenty-five 75 by 100-mm (3 by4-in.) panels under these test conditions can
18、be constructed asfollows (Fig. 1):4.2.1 Tank, polypropylene or polyethylene, with an offsetshoulder at the top rim is used as the chamber.4The minimumrecommended tank size is 46 by 46 by 61 cm (18 by 18 by 24in.). A pitched top with straight sides should be constructed outof acrylic plastic so moist
19、ure condensation will run down thesides and be recirculated instead of dripping onto the panels.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 w
20、hen the chamber 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. The temperature in the chamber should bemonitored and controlled by placing a suitable thermocouple orRTD8in an area near
21、the test panels. The temperature can bedisplayed and controlled by a solid state proportional control-ler.94.2.3 Tray, stainless steel or plastic, approximately 25 mm(1 in.) smaller than the inside dimensions of the chamber and25 to 75 mm (1 to 3 in.) deep with a noncorrodible metal10mesh bottom sho
22、uld be supported 25 mm (1 in.) above thewater level and centered in the chamber. One layer of fineplastic or fiberglass screen may be placed over the metal mesh,if needed for holding soil.NOTE 2It has been found that eliminating the plastic screen helpsimprove water vapor transfer into soil, and mai
23、ntain 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 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 inocula
24、ted soil with a suitable method offastening. Screw eyes are used with the wooden panels while awire frame or a large clip is used with the gypsum boardpanels. 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 Psychr
25、ometer, for measuring relative humidity in thetest area.5. Reagents and Materials5.1 SoilA good quality greenhouse-grade potting soil,suitable for plant propagation, containing 25 % peat moss. pHof the soil should fall from 5.5 to 7.6. Do not allow soil tobecome compacted.5.2 Cultures:5.2.1 Aureobas
26、idium pullulans,6,11ATCC 93485.2.2 Aspergillus niger,6,11ATCC 62755.2.3 Penicillium,6,11Sp. 12667 or ATCC 98495.3 Test Panels:5.3.1 Ponderosa Pine (Pinus ponderosa Laws) SapwoodPanels, 12.7 mm (12 in.) thick, 75 by 100 mm (3 by 4 in.), freeof excessive resins, knots, growth rings or other abnormalit
27、ies,surfaced smooth on four sides. Wood shall be kiln dried aftersawing to avoid infestation of wood-rotting fungi, and any4Tanks 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 sui
28、table.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, 8008484286.6If you are aware of alternative suppliers, please provide this informati
29、on toASTM International Headquarters. Your comments will receive careful consider-ation at a meeting of the responsible committee,1which you may attend.7For 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-watth
30、eater 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 be calibrated and provide calibratable, accurate, and reliableperfo
31、rmance.10150-mesh 316 stainless screen gives a high percentage of open area and willnot allow dirt to contaminate the water.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
32、 potato dextrose agar. Prepared slants can be obtained frommicrobiological supply companies.FIG. 1 Environmental Cabinet AssemblyD 3273 00 (2005)2wood showing evidence of such infestation shall be eliminatedas test material. Wood shall be weighed after conditioning atroom temperature in a dry room t
33、o 15 % moisture content.Calculated weight shall fall between 365 and 425 kg/m3( 6.0and 7.0 g/in.3). Panels containing heartwood areas should notbe used as they will inhibit mold growth under test conditions.5.3.2 Gypsum Board Panels, 12.7 mm (12 in. ) thick, 75 by100 mm (3 by 4 in.).5.3.3 Other Subs
34、trates such as Drawdown Paper, TongueDepressors, 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. Also, when usingsubstrates that are not th
35、emselves susceptible to attack (likeglass), another type of positive growth control must be usedrather than the uncoated 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 t
36、o equilibrate for 24 h before inoculating the soil withthe specified mold suspensions.6.2 Prepare mold slants of all three cultures and age 10 to 14days or purchase prepared mold slants9of all three cultures.Prepare mold suspensions from each type of mold slant by thefollowing procedure: Add one dro
37、p of 25 % nonionic surfac-tant12solution to 95 to 100 mL sterile deionized or distilledwater and shake. Pipet 5 mL of this solution onto the moldslant. Scrub the surface of the slant with a sterile cotton swabto remove as much spore and mycelial growth as possiblewithout digging up the surface of th
38、e agar. Pour the water fromthe scrubbed slant back into the surfactant-sterile water mixturefor dilution. Shake gently for 15 to 20 min to break up clumpsof mold. Use a pipet to distribute the mold suspensions evenlyover the surface of the greenhouse soil in the tray in thecabinet.6.3 Allow two week
39、s of continuous operation for the moldto sporulate and equilibrate with the environment beforestarting a test. It should not be necessary to recontaminatecontinually the chamber of panels after sufficient microorgan-ism growth has built up in the soil, if the chamber is maintainedin continuous opera
40、tion.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(906 2F) for 3 days. If an incubator is notavaila
41、ble, 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 plasticgloves or utilize other techniques when handling panels toavoid fingerprints. Prepare triplicate p
42、anels by applying twocoats of the material under test to both faces and to all edges ofthe panels at a spreading rate of approximately 11 m2/L (450ft2/gal) per coat or as specified by the coating manufacturer,allowing 1 day between coats unless otherwise specified.Duplicates may be run instead of tr
43、iplicates, if agreed upon byparties involved. Condition the panels at 23 6 2C (73.5 63.5F) and 50 6 5 % relative humidity for 4 days afterapplication of the last coat before placing in the test chamberfor start of environmental exposure.7.2 ExposureHang the panels vertically with the bottomapproxima
44、tely 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 panels or with wall surfaces.Place replicate panels randomly in the cabinet. Include un-coated control panels, or panels coated with a material know
45、nto fail under the test condition if the subtrate is not susceptibleto mildew 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 isso
46、me interfering treatment on the panel.7.3 RatingRate the panels for mold growth each week for4 weeks ona0to10rating scale using photographic standards(Test Method D 3274). The 50 and 100 magnification photo-graphic standards for types of fungal or dirt disfigurement (TestMethod D 3274) should be use
47、d to confirm the presence ofmold as the cause of discoloration.8. Report8.1 Report the results at the end of the 4-week exposuregiving the mean and range of the three panels. The result fromany panel that differs by more than 2 rating units from either ofthe others can be considered manifestly fault
48、y and discardedand the mean of the remaining two panels reported. If allpanels in a set differ by more than 2 units in their ratings,discard all results and repeat the test.9. Precision and Bias9.1 On the basis of an interlaboratory study of this testmethod in which one operator, in each of seven la
49、boratories,rated resistance to mold growth of interior paints at sevenlevels of resistance by visual comparison with photographicstandards, the standard deviations within and between labora-tories were found to be:Standard DeviationsWithin laboratories 0.4 unitsBetween laboratories 0.7 unitsBased on these deviations the following criteria should beused to judge the precision of results at a 95 % confidencelevel:9.1.1 RepeatabilityTwo ratings, each the mean of a set,obtained by a single operator should be considered suspect ifthey differ by more than 1 uni
