ASTM_D_6846_-_02_2012.pdf

Designation:D684602(Reapproved 2012)Standard Practice forPreparing Prints of Paste Printing Inks with a Printing Gage1This standard is issued under the fixed designation D6846;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 This practice covers the procedure for preparing labo-ratory prints of paste inks using a printing gage in conjunctionwith a flat-bed proof press.1.2 This practice is applicable to the preparation of solid-area prints by direct letterpress or by dry offset on a flatsubstrate such as paper,paperboard,or metal.1.3 This practice is applicable primarily to lithographic andletterpress inks that dry by oxidation or penetration.With theaddition of appropriate drying or curing equipment,it is alsoapplicable to other paste ink systems such as heat-set orenergy-curable.1.4 The instructions in this practice are intended to mini-mize the within-print and among-operator variability inherentin hand operations.1.5 This practice features built-in ink film thickness control.It does not measure the film thickness transferred to the print;however,film thickness equivalence may be evaluated byvisual or instrumental comparisons of optical density.1.6 Values stated in SI units are to be regarded as thestandard.The values given in parentheses are for informationonly.1.7 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.Specific precau-tions are given in Section 7.2.Referenced Documents2.1 ASTM Standards:2D1316 Test Method for Fineness of Grind of Printing InksBy the NPIRI GrindometerD6073 Test Method for Relative Setting of Heatset PrintingInksD6487 Practice for Preparing Prints of Paste Printing InksUsing a Hand Operated Laboratory Flat-Bed Press3.Summary of Practice3.1 The printing gage is inked by a drawdown technique;adouble drawdown is recommended to minimize scratches andimprove print appearance.3.2 The inked gage is placed in the bed of the proof pressfrom which the regular printing plate has been removed.3.3 To make a letterpress print,the appropriate stock isattached to the impression(blanket)cylinder,which is rolledonce over the inked gage.To make a dry offset print,the stockis clipped onto the impression plate and the blanket cylinder isrolled over the inked printing gage two to four times followedby once over the stock.3.4 Two-color prints may be prepared by utilizing two inkedgages in the bed of an offset proofing press.4.Significance and Use4.1 Laboratory proofing of inks is necessary to establish areproducible prediction of print appearance and performanceproperties,most of which are highly sensitive to ink filmthickness.The apparatus described in this practice has foundwide use for routine control proofing because it provides aneconomical method for producing reasonably large prints atfilm thicknesses comparable to those obtained on productionpresses.4.2 A unique advantage of printing gages is that,dependingon the design selected,prints can be produced at a range oftapered film thicknesses or at several levels of uniformthicknesses in a single proofing.Because of the built-in filmthickness control,ink metering is not necessary.Relativelysmall quantities of test samples are used,and less than twominutes are required to ink a gage,pull a letterpress print,andclean up.In addition,problems due to ink distribution systemsare eliminated,two inks may be proofed at the same time,andmulti-color printing is possible.4.3 This practice does not duplicate the dynamics of a highspeed press,nevertheless,it is useful for quality control and forspecification acceptance between the producer and the user.1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.56 on Printing Inks.Current edition approved June 1,2012.Published August 2012.Originallyapproved in 2002.Last previous edition approved in 2007 as D6846 02(2007).DOI:10.1520/D6846-02R12.2For 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 States1 5.Apparatus5.1 Printing Gage,3consisting of a type-high(approximately23.3 mm,0.918 in.)block of steel,the top surface of whichcontains precision-machined channels that may be tapered indepth similar in principle to the grind gages described in TestMe