BS ISO 11556:2005

Foreword
Introduction
1 Scope
2 Normative references
3 Terms and definitions
4 Principle
5 Apparatus
6 Sampling
7 Preparation of test pieces
8 Procedure
   8.1 General information
   8.2 Method
       8.2.1 Exposing the test pieces to the test environment
       8.2.2 Measurement of chord length and chord-to-arc
             distance
       8.2.3 Identification of the side towards which the
             paper or board curls
       8.2.4 Measurement of the angle of axis of curl
9 Calculations
   9.1 Magnitude of curl
   9.2 Angle of curl axis
   9.3 Variation in side towards which paper or board curls
10 Repeatability and reproducibility
   10.1 Repeatability
   10.2 Reproducibility
11 Test report
Annex A (informative) Illustrations of magnitude and types
                      of curl
Annex B (normative) Method of test piece support during
                      curl measurement (illustrated for
                      circular test pieces)
Annex C (normative) Modified engineer's vernier calliper
                      for determining chord length (C) and
                      chord-to-arc distance (h)
Annex D (informative) Examples of alternative curl calculations
Bibliography

Provides a procedure for determining the curl of paper and board using a vertically suspended test piece, and defines the terms used in curl measurement.

This International Standard gives a procedure for determining the curl of paper and board using a vertically suspended test piece, and defines the terms used in curl measurement.

This International Standard may be used to measure any curl when

• the curl formed approximates the arc of a circle;

• the curl is stable enough to remain constant during the time required to cut the test pieces and make the measurement. This primarily includes curl in paper or board as received or after exposure to a constant climatic condition, such as a test room or print shop.

NOTE1 The choice of conditioning climate and conditioning time depends on the purpose of the testing.

NOTE2 For papers coated on one side or gummed-label papers, a period of at least 24h, after production, should be allowed to permit the paper to stabilize before any curl tests are done.