ISO 14968 pdf download.Paper and board — Cut-size office paper — Measurement of curl in a pack of sheets
1 Scope
This International Standard specifies a method for the measurement of curl in cut-size office papers. The test method would typically be used in evaluating papers of the type described in ISO 216. This method is limited to papers with a maximum dimension of 300 mm in both directions. The measurement may be made on papers as received, after conditioning, or after processing in a copier or printing device.
2 Normative references
The following standards contains provisions which, through reference in the text, constitute provisions of this International Standard. At the time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the standards indicated below. Members of IEC and ISO maintain registers of currently valid International Standards. ISO 186:1994, Paper and Board — Sampling to determine average quality . ISO 187:1990, Paper, board and pulps — Standard atmosphere for conditioning and testing and procedure for monitoring the atmosphere and conditioning of samples . ISO 21 6:— 1 ) , Writing paper and certain classes of printed matter — Trimmed sizes — A and B series.
3 Definitions
For the purposes of this International Standard, the following definitions apply. 3.1 curl deviation from a flat surface which has three major components: magnitude, direction of curl axis and the side towards which the paper curls 3.1.1 curl magnitude quantitative measure of the deviation of a paper test piece from a flat surface NOTE 1 It is expressed as the reciprocal of the radius of curvature, R, of the curled test piece with units of reciprocal metres (m −1 ). NOTE 2 The radius of curvature for the curled test piece is the distance from the arc to the centre of a circle, of which the arc forms a part. The reciprocal radius ( R −1 ) has a value of zero for a flat sheet. NOTE 3 Curl characteristics of paper and board are time-dependent and the magnitude of any curl may be transient. 3.1.2 curl axis direction direction of the curl axis of paper and board, characterized as follows: – curl axis which is perpendicular to the paper’s machine direction; – curl axis which is parallel to the paper’s machine direction; – curl axis which is neither parallel nor perpendicular to the paper’s machine direction. NOTE See figures A.1 to A.3 respectively. 3.1.3 concave side side towards which the paper or board curls NOTE See also annex A. 3.2 double curl form of curl which tends to alternate between the two sides, when the sheet is manipulated lightly NOTE This tendency is a phenomenon which may be described as two curl patterns that are finely balanced within the same sheet of paper. 3.3 cut-size office papers papers in the range 60 g/m 2 to 1 50 g/m 2 which are used for writing and/or in various printing and copying devices 3.4 reference side for a non-imaged paper that side indicated by arrows on the end labels of a sealed ream, that side facing the top of a box of unwrapped sheets or, if arrows, or other instructions, are not present, that side facing the wrapper seam
5 Apparatus
5.1 curl gauge, consisting of a straight line 21 0 mm long and companion arcs at least 21 0 mm long of radii such that their curl magnitude varies between 1 ,00 m −1 and 1 0,00 m −1 . The construction of such a gauge is shown in annex B. NOTE 1 Copies of the curl gauge made on a toner-imaging device should not be used because such a device frequently has a built-in enlargement which would change the dimensions of the arcs. NOTE 2 It may be convenient to use a set of templates with their edges corresponding to the curl of magnitudes given in annex B. Each template should be labelled with its curl magnitude.