1、Designation: D 7433 08Standard Test Method forMeasuring Surface Water Absorption of Overlaid Wood-Based Panels1This standard is issued under the fixed designation D 7433; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、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.1. Scope1.1 This test method covers the determination of the quan-tity of water absorbed in a specified time through the surface
3、ofan overlaid wood-based panel. The test method measures therate of water weight gain within a controlled surface area of theoverlaid panel surface when exposed to standing water. Themethod was adapted from the principles of Test MethodD 5795.1.2 This test method is applicable to various overlaidwoo
4、d-based panels including, but not limited to, plywood(such as MDO and HDO referenced in PS 107), orientedstrand board, medium density fiberboard, particleboard, andhardboard.1.3 This test method does not address sampling procedures,number of replications nor performance criteria since thosedetails v
5、ary depending upon the purpose of the testing and thetype of product. The method is specific to the panel surface anddoes not evaluate water absorption or edge swell that mayoccur along panel edges. The method does not consider thevariables related to in-service moisture conditions and there-fore do
6、es not claim to directly relate to water absorption thatmay occur in actual panel use situations.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 an
7、y, 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:2D 5795 Test Method for Determination of Liquid Wat
8、erAbsorption of Coated Hardboard and Other CompositeWood Products Via“Cobb Ring” ApparatusD 4442 Test Methods for Direct Moisture Content Measure-ment of Wood and Wood-Base Materials2.2 Other Standards:3PS 107 U.S. Voluntary Product Standard, Structural Ply-wood3. Significance and Use3.1 Water absor
9、ptiveness through the surface of an overlaidpanel is a function of various characteristics of the overlay andsubstrate, including overlay resin content, thickness of theoverlay, porosity, and permeability.3.2 This test method is useful in comparing the waterabsorption characteristics of different ov
10、erlaid panel products.The results from this test method are influenced by both theperformance of the overlay system and the panel substrate.Therefore, the results are appropriate for comparison of therelative performance of an overlay system when tested oversimilar or matched panel substrates.NOTE 1
11、Panel attributes that may influence water absorption include,but are not limited to, panel type, wood species, face veneer thickness andgrade, preoverlay surface treatment such as sanding, particle geometry andcompaction ratio.4. Test Apparatus and Materials4.1 Rings, formed by cut sections of metal
12、 or plastic pipewith inside diameter of approximately 108 mm (4.25 in.) whichcan be sealed to the overlaid panel with silicone or elastomericsealant.4.2 Scale, to measure the depth of water column within 0.5mm (0.020 in.) accuracy. The cross section of the scale shall beas small as practical to mini
13、mize interference with the waterdepth.NOTE 2A steel pocket scale with etched graduations at 0.01 in. issuitable.4.3 Mixture of equal parts beeswax and rosin, to create acoating for the exterior of the specimen in order to preventweight change due to absorption or desorption of moisturefrom the panel
14、 specimen in areas other than the test area.1This test method is under the jurisdiction of ASTM Committee D07 on Woodand is the direct responsibility of Subcommittee D07.03 on Panel Products.Current edition approved Feb. 1, 2008. Published February 2008.2For referenced ASTM standards, visit the ASTM
15、 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 website.3Available from National Institute of Standards and Technology (NIST), 100Bureau Dr., Stop 1070, Gaithersbu
16、rg, MD 20899-1070, http:/www.nist.gov/standards1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.4 Hotplate and suitable pan for melting the mixture ofbeeswax and rosin in which the specimens are dipped.4.5 Balance, with an accuracy
17、of 0.01 g.4.6 Water, distilled or deionized.4.7 Sealant, 100 % silicone or elastomeric, which do notcontribute to the assembly weight change through absorptionof water.4.8 Aluminum foil or other sheet material that will form avapor resistant seal.5. Test Procedure5.1 Specimen Preparation:5.1.1 When
18、a standardized dry initial condition is required,the panels shall be brought to moisture equilibrium in aconditioned environment of 20 +/-6 C (68 +/- 11 F) and 65%(+/- 5%) relative humidity.NOTE 3Depending upon the purpose of the tests, other panel moistureconditions are permitted.5.1.2 The initial
19、panel moisture content of adjacent speci-mens shall be measured in accordance with Test MethodD 4442.5.1.3 Cut overlaid panel test specimens to 150 3 150 mm(6.0 3 6.0 in.).5.1.4 Measure the inside diameter of the ring to the nearest0.5 mm (0.02 in.).5.1.5 Apply a bead of silicone or elastomeric seal
20、ant to theend of the ring.NOTE 4The bead of sealant should be approximately 3 mm (0.125 in.)for suitable performance.5.1.6 Center the ring over the face of the specimens, thenpress and position the ring against the specimen to obtain agood seal.5.1.7 Allow the sealant to cure for a minimum of 48 hou
21、rsat 20 +/-6C (68 +/-11F).5.1.8 Seal all specimen surfaces of the specimen outside ofthe ring by dipping the specimen into a molten mixture of 50 %beeswax and 50 % rosin.5.2 Specimen Exposure to Water:5.2.1 Weigh the specimen to an accuracy of 0.01 gram.Place the specimen on a level surface. Fill th
22、e ring with waterto a depth of 25.4 mm with a tolerance of +0.5/-0.0 mm (1 in.,+ .02/-0.00 in.). Measure and record the water depth.5.2.2 Cover the ring with aluminum foil or other suitablevapor barrier to prevent evaporation.5.2.3 Measure and record the height of the water columnafter soaking for 2
23、4 h, +0.2/-0.0 h. Add water if needed toreturn the water level to 25.4 mm with a tolerance of +0.5/-0.0mm (1.00 in., +0.02/-0.00 in.).5.2.4 Measure and record the height of the water columnafter soaking for a total of 48 h, +0.2/-0.0 h. Empty the waterfrom the rings and blot the area dry.5.2.5 Rewei
24、gh the specimens to an accuracy of 0.01 g.5.3 Calculate the water absorption through the surface.5.3.1 Calculate the area of the overlay exposed to wettingfrom the measured inside diameter of the pipe.5.3.2 Compute the water absorption (WA48) as follows:WA485 F I!/A (1)where:WA48= Water absorption a
25、t 48 h, gram/m2,F = weight of specimen after 48-h soak, g,I = weight of specimen before exposure to water, g,A = area of specimen exposed to wetting, m2.6. Report6.1 Report the following information for each test.6.2 The initial moisture condition and moisture content ofthe panel specimens.6.3 A des
26、cription of the overlay.NOTE 5The relevant descriptive details of the overlay will varydepending upon the purpose of the test, but should include informationsuch as manufacturer, resin loading, thickness.6.4 A description of the substrate panel.NOTE 6The relevant descriptive details of the panel sub
27、strate willvary depending upon the purpose of the test, but should include informa-tion such as manufacturer, panel type, wood species of the surface layer,thickness, panel grade or grade of surface that is overlaid.6.5 Total duration of water soak to the nearest one-tenthhour.6.6 Depth of water col
28、umn at beginning of soak period andat 24- and 48-h exposure periods.6.7 Water absorption at 48 h, calculated as the grams ofwater absorbed per square meter.6.8 Any deviations from these methods shall be reported.7. Precision and Bias7.1 There has not been a study to determine repeatabilityand reprod
29、ucibility of this method.7.2 BiasNo bias statement is available for this test methoddue to the lack of an acceptable homogeneous referencematerial.8. Keywords8.1 wood-based panels; water absorption; overlays; CobbRingD7433082ASTM International takes no position respecting the validity of any patent
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