ASTM_D_4825_-_97_2002.pdf

Designation:D 4825 97(Reapproved 2002)An American National StandardStandard Test Method forMeasurement of Curl in Cut-Sized Office Paper1This standard is issued under the fixed designation D 4825;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the measurement of curl incut-sized office papers at ambient conditions.The test methodwould typically be used in evaluating papers described inSpecification D 3460 or after processing in a copier or printingdevice.1.2 Cut-sized office papers are generally described as hav-ing dimensions of 812by 11 in.,812by 13 in.,812by 14 in.,and 11 by 17 in.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 and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 528 Test Method for Machine Direction of Paper andPaperboard2D 585 Practice for Sampling and Accepting a Single Lot ofPaper,Paperboard,Fiberboard,and Related Products2D 685 Practice for Conditioning Paper and Paper Productsfor Testing2D 3460 Specification for White Watermarked and Unwater-marked Bond,Mimeo,Spirit Duplicator,Reprographic andLaser Printer Cut-Sized Office Papers2D 5039 Test Methods for Identification of Wire Side ofPaper23.Summary of Test Method3.1 A lift of approximately 10 to 20 sheets of paper areremoved from a sealed ream and the curl is measured notingthe axis,direction,and magnitude of the curl.3.2 The tests can be conducted at 50%relative humidity orat ambient conditions if it is carried out quickly.4.Significance and Use4.1 Curl in cut sized paper plays an important part in howpaper performs in its intended use.Frequently cut-sized papersare used in duplicators and copy machines operating at highspeeds.Inherent curl,that is,curl in the ream before enteringthe process and curl developed during the imaging process,canaffect its performance,especially if duplexing(two-side print-ing)or collating is involved.Common problems experiencedinclude jamming and misregistration.4.2 The experience used in developing the test method waslimited to uncoated writing papers in the commonly used cutsizes.The technique is basic and could be used with coatedpapers as well as paperboard to identify the type and magnitudeof curl.4.3 The test method identifies the type and degree of curl ina pack of sheets and does not address variations that might beinherent in individual sheets.If during the testing process it isobserved that one or more sheets reacts in a contrary manner tothe lift,it should be noted.Curl of a single sheet may notnecessarily be determined by this procedure.5.Apparatus5.1 Curl GageA curl gage can be developed whichconsists of a straight line 216 mm(812in.)long and companionarcs each 216 mm(812in.)long of a radius such that thedistance between the arc and the chord intersecting the arccircumference at the 216-mm(812-in.)length is 10 mm,15mm,20 mm,and 30 mm.An example of such a gage is shownin Fig.1.NOTE1Copies made on a xerographic copier of the curl gage shouldnot be used because those devices frequently have a built-in enlargementwhich would change the dimensions of the arcs.A curl gage can bedeveloped using the following relation between the distance between thechord and the arc and the arc radius.1This test method is under the jurisdiction of ASTM Committee D06 on Paperand Paper Products and is the direct responsibility of Subcommittee D06.92 on TestMethodsCurrent edition approved May 10,1997.Published February 1998.Originallyapproved in 1988.Last previous edition approved in 1992 as D 482592e1.2Annual Book of ASTM Standards,Vol 15.09.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.DistanceRadius5 mm116.5 cm10 mm58.0 cm15 mm38.6 cm20 mm28.8 cm25 mm22.9 cm30 mm18.9 cm35 mm16.0 cm40 mm13.9 cm5.2 Measuring Device A measuring device can be fabri-cated that resembles the letter T.The horizontal member is 216mm(812in.)long.The vertical member is a rule calibrated inmillimetres and mounted so as to be able to slide in the verticalposition.This allows the distance between the end of the ruleand the straight edge of the horizontal member to be deter-mined.An example of such a fixture is shown in Fig.2.6.Sampling6.1 Select packages of cut-sized paper in accordance withPractice D 585.6.2 When measuring paper from unopened packages,openthe package,pull out 10 to 20 sheets from the pack,and makethe measurement in 5 min or less after the sheets are removedfrom the pack.Do not pull sheets from the top or bottom of thepack.6.3 When measuring paper from stacks that are