1、Designation: D 281 95 (Reapproved 2007)Standard Test Method forOil Absorption of Pigments by Spatula Rub-out1This standard is issued under the fixed designation D 281; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t 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. Scope1.1 This test method covers the determinati
3、on of the oilabsorption of pigments by the spatula rub-out technique.1.2 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. I
4、t 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 234 Specification for Raw Linseed Oil3D 1483 Test Method for Oil Absorption o
5、f Pigments byGardner-Coleman Method3. Summary of Test Method3.1 A stiff, putty-like paste is formed by the dropwiseaddition of linseed oil to pigment that is being thoroughlyrubbed with a spatula. The amount of oil required to producethe end point is used to calculate an oil absorption value.4. Sign
6、ificance and Use4.1 The oil absorption value obtained by this test methodgives information about the vehicle demand of the pigmentwhen it is used in a pigment paste. Oil absorption values can beused to characterize pigments or batches of a given pigment.4.2 This test method differs from Test Method
7、D 1483 inthat D 1483 involves only a gentle stirring and folding of thepigment, whereas this test method requires a thorough rubbingaction. Because the end points are different, the values obtainedfrom the two test methods generally differ.5. Apparatus and Materials5.1 Balance, capable of weighing t
8、o 0.001 g.5.2 Dropping Bottle, fitted with ground-in pipet and rubberbulb or buret, graduated in 0.1-mL divisions.5.3 Smooth Glass Rub-up Plate or Marble Slab (glassshould have a surface similar to Hoover Muller Plates).5.4 Spatula, sharp-edged, steel, having a blade of 15 or 20mm by 100 mm (12 or34
9、 by 4 in.).5.5 Oil, linseed, raw, conforming to Specification D 234except that it shall have an acid number of 3 6 1. Linseed oilused in comparative tests must have the same acid value. Otherliquids, such as refined oil, may be used by mutual agreement.6. Procedure6.1 Procedure A (Weighing Bottle)We
10、igh exactly 1 g, orany multiple thereof (Note 1), of the thoroughly mixed and airdried pigment and place upon a glass plate or marble slab.Weigh to 0.01 g a dropping bottle containing raw linseed oilalong with the pipet and rubber bulb. Add the linseed oilgradually, drop by drop (by means of the pip
11、et), to the pigment.After the addition of each drop, thoroughly incorporate the oilby rubbing up with the spatula. The test is complete whenexactly enough oil has been incorporated with the pigment toproduce a very stiff, putty-like paste, that does not break orseparate. Weigh the bottle and oil to
12、0.01 g and determine bydifference the weight of oil used.NOTE 1The specimen weight depends upon the specific gravity,fineness, and other characteristics of the pigment. For example, 20 g istaken for white lead, but about 1 g is sufficient for carbon black. In anyevent, the specimen size should be la
13、rge enough so that at least1gofoilis required.6.2 Procedure B (Buret):6.2.1 Follow Procedure A, except add the linseed oil from aburet rather than a dropping bottle pipet. Calculate the weightof oil in grams by multiplying the volume oil used by itsdensity (0.93 g/mL).6.3 It is suggested that when a
14、 new pigment is to be tested,a preliminary rub-out be made to determine an approximateend point. Once this is established, the actual determination1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings, Materials, and Applications and is the direct responsibil
15、ity ofSubcommittee D01.24 on Physical Properties of Liquid Paints and Paint Materials.Current edition approved July 1, 2007. Published July 2007. Originally approvedin 1928. Last previous edition approved in 2002 as D 281 95 (2002).2For referenced ASTM standards, visit the ASTM website, www.astm.org
16、, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.sho
17、uld be made with a slower addition of oil and a morevigorous rub-out through the critical region, therefore permit-ting a more precise assessment of the correct oil absorption endpoint.7. Calculation7.1 From the weights of oil and pigment used in the test,calculate the number of grams (pounds) of oi
18、l required toexactly wet grams of oil per 100 grams of pigment or 100pounds of pigment.8. Report8.1 Report the oil absorption of the pigment as the numberof grams (pounds) of oil required to exactly wet 100 grams(pounds) of pigment.9. Precision and Bias9.1 On the basis of an interlaboratory study of
19、 this testmethod in which one operator in each of five laboratories testedtwo grades of zinc oxide covering a small oil absorption rangeby spatula rub-out, the within-laboratory coefficient of varia-tion was found to be 4.6 % at 10 df and the between-laboratories coefficient of variation 11.6 % at 8
20、 df. Based onthese coefficients, the following criteria should be used forjudging the precision of results at the 95 % confidence level:9.1.1 RepeatabilityTwo results obtained by a single op-erator should be suspect if they differ by more than 14.3 %relative.9.1.2 ReproducibilityTwo results obtained
21、 by operators indifferent laboratories should be considered suspect if theydiffer by more than 38.0 % relative.9.2 BiasSince there is no accepted reference materialsuitable for determining bias for the procedure in this testmethod, bias cannot be determined.10. Keywords10.1 oil absorption; pigments
22、(general properties); spatularub-out testASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and th
23、e riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision o
24、f this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you should
25、make your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 281 95 (2007)2
