ASTM_D_4942_-_20.pdf

Designation:D494220Standard 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.Scope1.1 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,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.5 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.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.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 1,2020.Published June 2020.Originallyapproved in 1989.Last previous edition approved in 2011 as D4942 11 which waswithdrawn January 2020 and reinstated in June 2020.DOI:10.1520/D4942-20.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.7.Conditioning7.1 Condition the instrument,water,and ink samples in aconstant temperature room or bath,preferably at 23 6 1C.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