ASTM_D_281_-_12_2021.pdf

Designation:D28112(Reapproved 2021)Standard Test Method forOil Absorption of Pigments by Spatula Rub-out1This standard is issued under the fixed designation D281;the number immediately following the designation indicates the year oforiginal adoption or,in the case 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.1.Scope1.1 This test method covers the determination of the oilabsorption of pigments by the spatula rub-out technique.1.2 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.3 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2D1483 Test Method for Oil Absorption of 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.Significance 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 D1483 in thatD1483 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 to 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(12or34by 4 in.).5.5 Oil,linseed,raw,conforming to the following specifi-cation:Specific Gravity0.9260.931Boiling Point149CAcid Number3 1Saponification Value185196Iodine Value170 minimumGardner Color13 maximum5.5.1 Linseed oil used in comparative tests must have thesame acid value.Other liquids,such as refined oil,may be usedby mutual agreement.6.Procedure6.1 Procedure A(Weighing Bottle)Weigh 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 pipet),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 0.01 g and determine bydifference the weight of oil used.The time that it took to runthe test(in minutes)should be noted.Subsequent tests on the1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.24 on Physical Properties of Liquid Paints&Paint Materials.Current edition approved June 1,2021.Published June 2021.Originallyapproved in 1928.Last previous edition approved in 2016 as D281 12(2016).DOI:10.1520/D0281-12R21.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1same kind of pigment should be performed in approximatelythe same period of time.Any device capable of measuringminutes may be used.NOTE1The specimen weight depends upon the