1、Designation: D 3723 05Standard Test Method forPigment Content of Water-Emulsion Paints by Low-Temperature Ashing1This standard is issued under the fixed designation D 3723; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o
2、f 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 a procedure for the pigmentcontent determination of water-based paints. It is applicableonl
3、y to pigments that do not decompose or lose weight attemperatures below 500C. Such pigments include most metaloxides, silicates, and a majority of anhydrous inorganic salts.1.2 Many water-based paints contain pigments and organiccolorants that lose water of hydration or decompose at thistemperature.
4、 The residual ash should be carefully inspected forchanges in color or texture that could indicate a pigmentalteration and hence lead to erroneous results. Caution shouldtherefore be exercised when applying this test method tosamples containing unknown pigment compositions.1.3 The values stated in S
5、I units are to be regarded as thestandard. The values given in parentheses are for informationonly.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and healt
6、h practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 1193 Specification for Reagent Water3. Significance and Use3.1 This test method is used by paint producers and con-sumers for product process control and for product accep
7、tance.4. Apparatus4.1 Oven, forced draft, maintained at 105 6 2C.4.2 Furnace, muffle, maintained at 450 6 25C.4.3 Syringe, 5-mL.4.4 Aluminum Foil Dish, 58 mm in diameter by 18 mm highwith a flat bottom. The bottom of the dish should be as nearlyflat as possible so that a uniform film is produced.5.
8、Reagents5.1 Purity of ReagentsReagent grade chemicals shall beused in all tests. Unless otherwise indicated, it is intended thatall reagents shall conform to the specifications of the Commit-tee on Analytical Reagents of the American Chemical Society,where such specifications are available.3Other gr
9、ades may beused, provided it is first ascertained that the reagent is ofsufficiently high purity to permit its use without lessening theaccuracy of the determination.5.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Type III of S
10、pecification D 1193.5.3 Ammonium Hydroxide4Add 1 volume of concen-trated NH4OH (sp gr 0.90) to 3 volumes of water.6. Procedure6.1 Mix samples until homogeneous, preferably on a me-chanical shaker. If air bubbles become entrapped in a sample,stir it by hand.6.2 Draw approximately 1.5 g of the test pa
11、int into a 5-mLsyringe and weigh to 1 mg. Add the paint dropwise (about 30drops) into a tared-aluminum foil dish that contains 2 mL ofwater (5.2). Swirl the dish during the addition and continue theswirling until the specimen is completely dispersed. Reweighthe syringe to 1 mg. Transfer between 0.4
12、and 0.6 g of sampleto the dish. If not, adjust the transferred volume and prepare anew specimen. If the specimen agglomerates or forms a lumpthat cannot be dispersed, a drop or two of ammonia (5.3) mayfacilitate the dispersement. If the lumping persists, discard thespecimen and prepare a new one. Pr
13、epare a duplicate specimenin the same manner.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.21 on Chemical Analysis of Paints and Paint Materials.Current edition approved
14、Jan. 1, 2005. Published February 2005. Originallyapproved in 1978. Last previous edition approved in 1999 as D 3723 84 (1999).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information,
15、 refer to the standards Document Summary page onthe ASTM website.3Reagent Chemicals, American Chemical Society Specifications, AmericanChemical Society, Washington, DC. For suggestions on the testing of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals
16、, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeiaand National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville,MD.4For guidance in the safe handling of ammonium hydroxide consult theManufacturing Chemists Associations Chemical Safety Data Sheet.1Copyright ASTM Inter
17、national, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.3 Dry the specimen and dishes in the 105 6 2C oven fora minimum of 1 h after making certain that the dishes are level.If the coating does not uniformly cover the bottom of a dish,prepare a new specimen an
18、d repeat.NOTE 1The percent nonvolatile content, N, at 105C may be deter-mined by drying dishes to constant weight and calculating as follows:N 5A 2 BS3 100 (1)where:A = weight of dish and specimen after heating,B = weight of dish alone, andS = specimen weight.6.4 Transfer the dishes to a muffle furn
19、ace and heat at 4506 25C for 1 h. Remove from the furnace, cool in a desiccatorand weigh.7. Calculation7.1 Calculate the percent pigment content, P, as follows:P 5C 2 BS3 100 (2)where:C = weight of the dish and specimen after ignition in thefurnace,B = weight of the dish alone, andS = specimen weigh
20、t.8. Precision and Bias58.1 Precision: Pigment ContentOn the basis of an inter-laboratory test of this test method in which eighteen operatorsin nine laboratories analyzed three materials containing threepigment levels between 24 and 28 %, the within-laboratorystandard deviation was found to be 0.24
21、 % absolute and thebetween-laboratories 0.38 % absolute. Based on these standarddeviations, the following criteria should be used for judging theacceptability of results at the 95 % confidence level:8.1.1 RepeatabilityTwo results obtained by the sameoperator should be considered suspect if they diff
22、er by morethan 0.66 % absolute.8.1.2 ReproducibilityTwo results, each the mean of dupli-cate determinations, obtained by operators in different labora-tories should be considered suspect if they differ by more than1.05 % absolute.8.2 Bias: Pigment ContentOn the basis of the same study,the mean of tw
23、o determinations should be within 5 % relativeof the formula pigment content of a waterborne paint contain-ing only inorganic pigments.8.3 Precision: Nonvolatile Content On the basis of aninterlaboratory test of this test method in which fourteenoperators in seven laboratories analyzed three materia
24、ls con-taining three nonvolatile levels between 43 and 48 %, thewithin-laboratory standard deviation was found to be 0.18 %absolute and the between-laboratories standard deviation wasfound to be 0.445 % absolute. Based on these standard devia-tions the following criteria should be used for judging t
25、heacceptability of results at the 95 % confidence level:8.3.1 RepeatabilityTwo results obtained by the sameoperator should be considered suspect if they differ by morethan 0.49 % absolute.8.3.2 ReproducibilityTwo results, each the mean of dupli-cate determinations, obtained by operators in different
26、 labora-tories should be considered suspect if they differ by more than1.23 % absolute.8.4 Bias: Nonvolatile ContentBias cannot be determinedbecause there are no accepted standards for nonvolatile contentin coatings.9. Keywords9.1 low-temperature ashing; pigment content; water emul-sion paintsASTM I
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