1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 18907:2013Imaging materials Photographic films and papers Wedge test for brittlenessBS ISO 18907:2013 BRITISH STANDARDNational forewordThis British Standard is the UK impl
2、ementation of ISO 18907:2013.It supersedes BS ISO 18907:2000, which is withdrawn.The UK participation in its preparation was entrusted toTechnical Committee CPW/42, Photography.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not
3、 purport to include all the necessary provisions of a contract. Users are responsible for its correct application. The British Standards Institution 2013. Published by BSI Standards Limited 2013ISBN 978 0 580 80498 4 ICS 37.040.20 Compliance with a British Standard cannot confer immunityfrom legal o
4、bligations.This British Standard was published under the authority of the Standards Policy and Strategy Committee on 28 February 2013.Amendments issued since publicationDate Text affectedBS ISO 18907:2013 ISO 2013Imaging materials Photographic films and papers Wedge test for brittlenessMatriaux pour
5、 limage Films et papiers photographiques Dtermination de la mthode dite INTERNATIONAL STANDARDISO18907Second edition2013-02-01Reference numberISO 18907:2013(E)BS ISO 18907:2013ISO 18907:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All rights reserved. Unless otherwise s
6、pecified, no part of this publication may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below o
7、r ISOs member body in the country of the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 18907:2013ISO 18907:2013(E) ISO 2013 All rights reserved iiiContents PageForeword iv
8、Introduction v1 Scope . 12 Normative references 13 Terms and definitions . 14 Principle 15 Apparatus . 15.1 Wedge tester for brittleness 15.2 Test chamber 26 Sampling 26.1 Preparation of specimens 26.2 Selection of specimens . 26.3 Size of specimens 27 Conditioning and test conditions 47.1 Condition
9、ing of specimens . 47.2 Test conditions 58 Procedure. 59 Test report . 69.1 Test data 69.2 Significance 6Bibliography 7BS ISO 18907:2013ISO 18907:2013(E)ForewordISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The wo
10、rk 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-governm
11、ental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2.The ma
12、in task of technical committees is to prepare International Standards. 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.Att
13、ention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights.ISO 18907 was prepared by Technical Committee ISO/TC 42, Photography.This second edition cancels and repl
14、aces the first edition (ISO 18907:2000), of which it constitutes a minor revision with the following changes: Clause 2 has been updated; Annex A has been removed.iv ISO 2013 All rights reservedBS ISO 18907:2013ISO 18907:2013(E)IntroductionIn the case of photographic films and papers, brittleness is
15、an undesirable property since satisfactory performance in equipment or in handling requires sufficient flexibility (or lack of brittleness) to ensure good tolerances to bending stresses under the atmospheric conditions likely to be encountered in practice.Photographic films and papers are laminates
16、of two or more different materials, usually a plastic or paper support and firmly bonded gelatin layers that contain image forming and other substances. These laminate structures must have sufficient flexibility to withstand the stresses imposed by bending and flexing during use. However, under low
17、relative humidity and low temperature conditions, the gelatin layers and/or support tend to become brittle. This can cause the formation of cracks and/or breaks when the laminate is stressed beyond its diminished capacity to withstand bending and flexing.Different types of brittle failure occur when
18、 film and paper are subjected to stress in different ways. For example, failure can consist of very fine cracks in the emulsion (without a break in the support) which are objectionable when the photograph is viewed. Under different conditions or with different materials, failure can consist of crack
19、s in the support or a complete break of all components of the laminate.Brittleness is not an absolute physical property. The apparent brittleness of photographic material is very dependent upon the manner in which it is mechanically treated as well as the ambient conditions of temperature and relati
20、ve humidity. As a result, no one test for brittleness is capable of ranking a variety of types of photographic material as they would behave under widely different practical conditions.The wedge test for brittleness specified in this International Standard subjects the photographic material to a hig
21、h rate of strain in a simple folding action. It has been an accepted method of rating brittleness for many years and has correlated with product behaviour under many practical applications. It is a widely accepted method in the photographic industry. Other methods used have consisted of flex tests i
22、n which the specimen is subjected to a repeated folding action until it breaks, or the bending over mandrels of different diameters. There are a considerable number of flexibility tests available and standardization is not possible at this time.Brittleness is affected adversely by both reduced tempe
23、rature and reduced relative humidity. Brittleness at low relative humidity is encountered more frequently than brittleness at low temperature in most applications. Moreover, a marked change in brittleness can occur with only a very small change in relative humidity below a level of about 25 %. Conse
24、quently, brittleness tests are carried out only in an atmosphere which is very accurately controlled with respect to both temperature and relative humidity.Brittleness is also very dependent on the sample thickness, increasing with increasing thickness of either support or emulsion. For this reason,
25、 the thickness of the layers must be considered when comparing the behaviour of different materials. The thermal and moisture exposure history of the material between manufacture and testing can also affect the brittleness even though the sample is reconditioned to a standard temperature and humidit
26、y.Gelatin is generally more brittle than the support, so that photographic products having a gelatin layer on only one side are usually more brittle when bent with the gelatin side out (that is, gelatin under tension).Brittleness can vary with the bend axis depending upon the orientation of the supp
27、ort. There is generally no directional effect in the brittleness of the emulsion. ISO 2013 All rights reserved vBS ISO 18907:2013BS ISO 18907:2013Imaging materials Photographic films and papers Wedge test for brittleness1 ScopeThis International Standard specifies a method for determining and expres
28、sing quantitatively the brittleness of photographic film and papers. It does not, however, specify a universal brittleness test for all types of stress encountered for which special tests can be required to correctly rate the material for brittleness.The method is applicable to films with or without
29、 a gelatin backing and to fibre-based or resin-coated (RC) photographic papers. It may also be applied to either raw or processed materials although the brittleness level can be quite different after processing from that before processing.2 Normative referencesThe following documents, in whole or in
30、 part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 483, Plastics Small enclosures for conditio
31、ning and testing using aqueous solutions to maintain the humidity at a constant value3 Terms and definitionsFor the purposes of this document, the following terms and definitions apply.3.1brittlenessproperty of materials that causes them to break or crack when deformed by bending4 PrincipleMeasureme
32、nt of the opening of a wedge at which a specimen loop fails when subjected to high strains.5 Apparatus5.1 Wedge tester for brittlenessThe wedge tester for brittleness consists of two non-parallel metal plates or jaws, which form a wedge or V as shown in Figures 1 and 2. A clamp is attached to one ja
33、w at the narrow end of the wedge to hold one end of the specimen. A scale is provided which gives the wedge separation between the two jaws at any point (see Reference1).The dimensions for the wedge tester are standardized for both a narrow and a wide tester. The narrow wedge (see Figure 1) has a we
34、dge angle of 9 and a maximum wedge opening of 25 mm. It is generally satisfactory for most films. For more brittle films and papers, a wide wedge (see Figure 2) is recommended. It has a wedge angle of 28 and a maximum wedge opening of 74 mm.INTERNATIONAL STANDARD ISO 18907:2013(E) ISO 2013 All right
35、s reserved 1BS ISO 18907:2013ISO 18907:2013(E)5.2 Test chamberAn air-conditioned box or walk-in room shall be used for both conditioning and testing. The temperature shall be controlled within 1 C and the relative humidity to within 1 % of the specified values. The linear air velocity shall be at le
36、ast 15 cm/s.NOTE To control the relative humidity to this accuracy usually requires a dew point method.If a walk-in conditioned room is used, the air velocity shall be adequate to maintain the conditions specified. The number of personnel permitted in the room during testing shall be limited and pre
37、cautions shall be taken to prevent the operators breath reaching the material.6 Sampling6.1 Preparation of specimensSpecimens shall be cut in an atmosphere of 20 C to 23 C and from 40 % to 55 % relative humidity.NOTE If the specimens are cut at relative humidities lower than 40 %, it can be difficul
38、t to obtain smooth edges. Handling under these conditions can also cause emulsion cracking, which will affect the subsequent brittleness results. Exposure to relative humidities greater than 55 % can permanently alter the subsequent brittleness behaviour of some films and photographic papers.The cut
39、ter shall be of a precision type and shall be kept sharp so that the specimens edges are smooth and free of nicks. Rubber gloves shall be worn by the operator when handling the specimens, both in their preparation and testing.6.2 Selection of specimensA set of 10 specimens shall be prepared for each
40、 test. If there is sufficient material, one set of specimens should be cut in the machine direction and a second set in the transverse (cross) direction. If the film has a discrete backing layer, a separate set of specimens shall be cut in at least one of the two principal directions to enable testi
41、ng with the backing convex.6.3 Size of specimensThe standard specimen size shall be 350 mm long by 15 mm to 16 mm wide. If the sample size available does not permit a 350 mm specimen length, the length can be effectively increased by taping a film or paper leader to the specimen and placing the spec
42、imen end in the clamp.Although not recommended, 16 mm perforated film may be tested for comparative purposes only, by cutting off the perforated edges and testing a specimen 9 mm wide. Similarly, 35 mm film may be tested, but the results are not necessarily comparable to the standard 15 mm to 16 mm
43、width.2 ISO 2013 All rights reservedBS ISO 18907:2013ISO 18907:2013(E)Dimensions in millimetresKey1 clamp2 wedge opening scale3 wedge openingaThis dimension may vary from 2,5 mm to 25 mm.Figure 1 Narrow-wedge tester for brittleness ISO 2013 All rights reserved 3BS ISO 18907:2013ISO 18907:2013(E)Dime
44、nsions in millimetresKey1 clamp2 wedge opening scale3 wedge openingaThis dimension may vary from 2,5 mm to 25 mm.Figure 2 Wide-wedge tester for brittleness7 Conditioning and test conditions7.1 Conditioning of specimensSpecimens shall be conditioned in the test chamber until practicable moisture equi
45、librium has been reached. This may be determined by weighing the specimens at regular intervals and determining the time at which further conditioning does not appreciably change the mass. In many instances, this time will 4 ISO 2013 All rights reservedBS ISO 18907:2013ISO 18907:2013(E)be in the vic
46、inity of 4 h for photographic film, 1 d for fibre-based papers, and 7 d for RC papers. However, actual times will vary due to access of the conditioning air and the type and thickness of the material.The specimens shall be held in racks permitting free circulation of air.7.2 Test conditionsThe stand
47、ard relative humidity for testing shall be (15 1) %. However, other relative humidities such as 10 %, 20 %, and 35 %, or approximations thereof, utilizing stable saturated solutions in a closed box, can prove useful (see ISO 483).The standard temperature for testing shall be 23 C 1 C. However, other
48、 temperatures may be used where the effect of temperature is to be investigated.The specimen shall not be removed from the conditioning atmosphere for testing except at a temperature of 0 C. For testing film at 0 C or below, the specimens shall be conditioned at the desired relative humidity at 23 C
49、, sealed in small, taped cans, cooled long enough to reach the test temperature, and then removed, one at a time, for testing.NOTE Direct control of relative humidity at temperatures of 0 C or below is impracticable, but once photographic material is conditioned, the rate of gain or loss of moisture is much lower at low temperatures.8 ProcedureFasten one end of the specimen in the clamp at the narrow end of the wedge. Loop the material, emulsion side out, within the wedge, with a sufficient length at the free
