ISO INTERNATIONAL STANDARD 5626 Second edition 1993-11-15 Paper -- Determination of folding endurance Papier Détermination de la résistance au pliage so Reference number ISO 5626:1993(E) No reproduction or networking permitted without license from IHS Not for Resale ISO5626:1993(E) Foreword federationof nationalstandardsbodies(lsOmemberbodies).Thework of preparing International Standards is normally carried out through Iso technical committees. Each member body interested in a subject for which a technical committee has been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with isO, also take part in the work. iso collaborates closelywith theInternational Electrotechnical Commission (IEC) on all matters of electrotechnical standardization. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. International Standard ISO 5626 was prepared by Technical Committee ISO/TC 6, Paper, board and pulps, Sub-Committee SC 2, Test methods and quality specifications for paper and board. This second. edition cancelsand replacesthefirstedition (Iso 5626:1978), of which it constitutes a technical revision (see intro- duction). Annexes A and B form an integral part of this International Standard. An- nex C is for information only. @ISO1993 All rights reserved. No part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without per- mission in writing from the publisher. International Organization forStandardization CasePostale56·CH-1211Geneve20·Switzerland Printed in Switzerland right international Organization for Standardization No reproduction or networking permitted without license from IHS Not for Resale ISO 5626:1993(E) Introduction A number of instruments for determining the folding endurance of paper Lhomargy, the MiT and the Schopper instruments. This International Standard is therefore based upon these four types of instrument. It should be noted, however, that the instruments do not give identical results. The first edition of this International Standard (ISO 5626:1978) specified that the result be reported as the logarithm (to the base 10) of the number of double folds before fracture. The reason for this was the widely held opinion that the relative folding endurances of different papers are best indicated when the test values are expressed logarithmically. This pro- cedure is still valid. However, experience during the life of the 1978 edition has shown that the interpretation of logarithmic results has caused con fusion and consequently results are frequently quoted as the number of double folds. In view of this, this International Standard allows the results to be reported as either folding endurance [the logarithm (to the base 10) of the number of double foldsj or the fold number (the antilogarithm of the folding endurance). therefore different to the understanding of fold number which existed prior to 1978 and which stll persists in some countries. for Standardizatior ili No reproduction or networking permitted without license from IHS Not for Resale