ASTM_D_4942_-_11.pdf

Designation:D494211Standard Test Methods forWater Pickup of Lithographic Printing Inks and Vehicles in aLaboratory Mixer1This standard is issued under the fixed designation D4942;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.1.Scope*1.1 These test methods cover two procedures for determin-ing the amount of water picked up by lithographic printing inksin a laboratory mixer.1.2 Test Method A covers single-point water pickup;TestMethod B covers the rate of water pickup.Both test methodsare applicable to any printing ink and vehicle intended for thelithographic printing process.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.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 health practices and determine the applica-bility of regulatory limitations prior to use.2.Summary of Test Methods2.1 These test methods utilize a laboratory mixer for beatingwater or other agreed upon fluid into the test ink.2.2 For single-point water pickup(Test Method A),50 mLof water is normally added to 50 g of ink and mixed in for 5min.The water picked up is determined from volumetricmeasurements of free water.2.3 For rate of water pickup(Test Method B),water is addedto 50 g of ink in increments of 20 mL and mixed in for 1 minor more over a cumulative time period totaling 10 min.Thewater taken up by the ink after each mixing interval isdetermined gravimetrically.3.Significance and Use3.1 The lithographic printing process requires that somedampening solution be emulsified into the ink.These testmethods provide a rapid means for determining water pickupunder laboratory conditions.Test results may be useful forspecification acceptance between the supplier and the cus-tomer.3.2 In order that results be comparable,the tests must be runat the same temperature and with the same type and quantity ofliquid added prior to mixing.3.3 The emulsions obtained in these test methods are oflarger particle size than those typically produced in printingnips.Because of these and other variables in the printingprocess,water pickup results do not by themselves predictlithographic printing performance.4.Apparatus4.1 Laboratory Mixer,equipped with a stainless steel speci-men bowl 83 mm wide and 88 mm high,mixer blades thatrotate at 90 r/min,and a timing device.4.2 Balance,accurate to 0.1 g,600-g capacity.4.3 Palette knives,two.4.4 Thermometer,quick response.4.5 pH Meter(optional).4.6 Conductivity Meter(optional).4.7 Graduated Cylinder,50 or 100-mL.5.Reagents and Materials5.1 WaterDeionized or distilled water,preferably having apH of 5.0 to 7.0(100 to 200 mL per sample);alternatively,fountain solution or other aqueous medium as agreed uponbetween the supplier and the customer may be used.5.2 Cleanup MaterialsNaptha and rags or tissues.6.Test Specimen6.1 A minimum of 100 g is sufficient for two determina-tions.Before removing ink from the can,stir or otherwiseensure that the ink specimen is representative.Close the canand replace sealing tape immediately after each ink removal.7.Conditioning7.1 Condition the instrument,water,and ink samples in aconstant temperature room or bath,preferably at 23 6 1C.1These test methods are under the jurisdiction of ASTM Committee D01 onPaint and Related Coatings,Materials,and Applications and are the directresponsibility of Subcommittee D01.56 on Printing Inks.Current edition approved June 1,2011.Published June 2011.Originallyapproved in 1989.Last previous edition approved in 2006 as D4942-89(2006).DOI:10.1520/D4942-11.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 7.2 Prior to use,check the alignment of the mixer blades.With the power switch of the mixer in the off position,set theclean bowl into the turntable and engage the locking pin firmlyinto the slot in the side of the turntable.Tilt the mixer headback and insert the blades,marked left and right,into theirrespective holders.Lower the mixer head.If the blades hit theside or bottom of the bowl,return the instrument to themanufacturer for realignment.8.Test Method ASingle Point Water Pickup(byVolumetry)8.1 Program the counter of the mixer for 5 min mixing time(450 revolutions).8.2 OptionalIf the first run of the day,pour test water intoa beaker.Measure pH,conductivity,and temperature at thebeginning of testing.8.3 Weigh or tare the clean dry mixing bowl.Add 50 6 0.1g of the ink to the center of the bowl.8.4 Pour 50 mL of water(from 8.2)into a graduatedcylinder.If the ink is expected to pick u