1、Reference number ISO 18915:2000(E) ISO 2000 INTERNATIONAL STANDARD ISO 18915 First edition 2000-12-15 Imaging materials Methods for the evaluation of the effectiveness of chemical conversion of silver images against oxidation Matriaux pour image Mthodes dvaluation de lefficacit de la conversion chim
2、ique des images argentiques contre loxydationISO 18915:2000(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on
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5、form the Central Secretariat at the address given below. ISO 2000 All rights reserved. Unless otherwise specified, 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 permission in writing from
6、 either ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.ch Web www.iso.ch Printed in Switzerland ii ISO 2000 All rights reservedISO 18915:2000(E) ISO
7、2000 All rights reserved iii Contents Page Foreword.iv Introduction.v 1 Scope 1 2 Normative references 1 3 Terms and definitions .1 4 Dichromate bleach test .2 5 Hydrogen peroxide incubation test .3 Annex A (informative) Numbering system for related International Standards8 Annex B (informative) Var
8、iable in silver stabilizing treatments .10 Annex C (informative) Significance of the test methods.11 Annex D (normative) Correction of density values .14 Bibliography16 Figure 1 Drawing of collar and baffles.4 Figure 2 Desiccator jar components5 Figure 3 Assembled desiccator jar.5ISO 18915:2000(E) i
9、v ISO 2000 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body intere
10、sted 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 closely with the International Electrotechnical
11、Commission (IEC) on all matters of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. Draft International Standards adopted by the technical committees are circulated to the member bodies for voting. Publication
12、 as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this International Standard may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such
13、patent rights. International Standard ISO 18915 was prepared by Technical Committee ISO/TC 42, Photography. This first edition cancels and replaces ISO 12206:1995, of which it constitutes a minor revision. This International Standard is one of a series of International Standards dealing with the phy
14、sical properties and stability of imaging materials. To facilitate identification of these International Standards, they are assigned a number within the block from 18900 18999 (see annex A). Annex D forms a normative part of this International Standard. Annexes A, B and C are for information only.I
15、SO 18915:2000(E) ISO 2000 All rights reserved v Introduction Silver-gelatin photographs have been used extensively for recording and preserving information of lasting value in all fields of human activity. The long-term stability of these records has become of increasing concern in recent years, bec
16、ause image and support degradation have been found with accelerating frequency in photographic collections and archives. ISO has published documents on various aspects of the stability and preservation of black-and-white silver-gelatin photographic materials. ISO 18901: 1) Imaging materials Processe
17、d silver-gelatin type black-and-white film Specifications for stability, provides test methods and criteria for the physical properties, permissible residual processing chemicals, and the image quality of films. ISO 18911:2000, Imaging materials Processed safety photographic films Storage practices,
18、 deals with the conditions required for maintaining and preserving the integrity of photographic films during storage. ISO 18902 2) , Imaging materials Processed photographic films, plates and papers Filing enclosures and storage containers, pertains to the materials used in contact with stored phot
19、ographic materials. If photographic film meets the material and processing specifications of ISO 18901 and is stored in accordance with ISO 18902 and ISO 18911, excellent stability will be obtained. Similarly, photographic paper prints should be stored in accordance with ISO 18920:2000, Imaging mate
20、rials Processed photographic reflection prints Storage practices, and processed photographic plates in accordance with ISO 18918:2000, Imaging materials Processed photographic plates Storage practices. However, in practical situations it is not always possible to control the storage conditions, part
21、icularly with respect to contaminants. Atmospheric pollutants such as peroxides, sulfur dioxide, ozone and nitrogen dioxide are very detrimental to silver images (see 1 in the bibliography). Such environmental pollutants are of increasing concern in our industrial society. They can cause oxidation o
22、f the silver with consequent silver migration. This results in image fading, silver mirroring and redox blemishes (see 2 and 3 in the bibliography). Oxidizing agents that diffuse out of enclosure materials cause similar defects. Recent studies have shown that silver images can be made resistant to o
23、xidizing pollutants by chemically treating the silver to form silver sulfide (see 4 in the bibliography) or silver selenide (see 5 in the bibliography), or by substitution of the silver by gold (see 6 in the bibliography). Such treatments are recommended when it is not possible to ensure the absence
24、 of contaminants, or when the importance of the image justifies the added expense. This International Standard is an adjunct to the processing requirements and describes methods for evaluating the effectiveness of various treatments which impart greater stability to silver images. 1) To be published
25、. (Revision of ISO 10602:1995) 2) To be published. (Revision of ISO 10214:1991)INTERNATIONAL STANDARD ISO 18915:2000(E) ISO 2000 All rights reserved 1 Imaging materials Methods for the evaluation of the effectiveness of chemical conversion of silver images against oxidation 1 Scope 1.1 This Internat
26、ional Standard describes methods for evaluating the effectiveness of chemical conversion treatments intended to increase the resistance of wet-processed silver images to oxidation. The treatment may be applied as part of the original processing, or it may be a post-processing treatment. This Interna
27、tional Standard does not recommend general or specific treatments for silver images. Likewise, treatment temperature, times and replenishment rates are outside the scope of this International Standard. Factors to be considered in a stabilizing treatment are discussed in informative annex B. Two test
28、 methods are described: the “dichromate bleach test“ and the “hydrogen peroxide incubation test“ (see 7 in the bibliography). The significance of each is discussed in informative annex C. 1.2 This International Standard is applicable to silver-gelatin images coated on supports of either plastic, pap
29、er or glass. 2 Normative references The following normative documents contain provisions which, through reference in this text, constitute provisions of this International Standard. For dated references, subsequent amendments to, or revisions of, any of these publications do not apply. However, part
30、ies to agreements based on this International Standard are encouraged to investigate the possibility of applying the most recent editions of the normative documents indicated below. For undated references, the latest edition of the normative document referred to applies. Members of ISO and IEC maint
31、ain registers of currently valid International Standards. ISO 5-2: 3 , Photography Density measurements Part 2: Geometric conditions for transmission density. ISO 5-3:1995, Photography Density measurements Part 3: Spectral conditions. ISO 5-4:1995, Photography Density measurements Part 4: Geometric
32、conditions for reflection density. 3 Terms and definitions For the purposes of this International Standard, the following terms and definitions apply. 3.1 treated silver images silver images that have been given a specific treatment, either during or after processing, to increase their stability 3 T
33、o be published. (Revision of ISO 5-2:1991)ISO 18915:2000(E) 2 ISO 2000 All rights reserved 3.2 toned silver images silver images that have been given a specific treatment, either during or after processing, to modify their colour 4 Dichromate bleach test 4.1 Principle This test consists of dissolvin
34、g the treated silver image and measuring the retained density. This retained density is proportional to the silver that has been chemically converted to a non-bleachable compound, or has been substituted by a non-bleachable element. 4.2 Reagents 4.2.1 Bleach solution A bleach solution shall be prepa
35、red by dissolving 90 g of anhydrous potassium dichromate in 1 litre of water. Subsequently, 96 ml of concentrated sulfuric acid shall be slowly added with constant stirring. WARNING Avoid contact with the eyes, skin, and clothing. Wash thoroughly after handling. In case of contact, flush eyes and sk
36、in with water. Obtain medical attention immediately. Take care to dispose of dichromate bleach solution in accordance with national and local regulations for hazardous waste disposal. 4.2.2 Clearing solution The clearing solution shall be prepared by dissolving 100 g of sodium sulfite in 1 litre of
37、water. 4.3 Specimen preparation Six uniform-density patches shall be prepared on the treated silver material with densities (D) ranging in approximately equal increments from 0,1 above D min to D max . The exact size of the patches is not critical, provided they cover the aperture of the densitomete
38、r and are easy to handle. 4.4 Procedure Measure the treated silver image on the six uniform-density patches and on the D min for status A blue density. Densities shall be measured on a densitometer having spectral conformance to ISO 5-3. The densitometer shall have geometric conformance to ISO 5-2 f
39、or photographic films and plates, and geometric conformance to ISO 5-4 for photographic papers. Then immerse the specimen in the bleach solution (4.2.1) for 30 s at (20 5) o C, rinse it in water for 2 s, and clear for 30 s in the clearing solution (4.2.2). Then rinse the specimen in water, dry it an
40、d remeasure the status A blue density. 4.5 Calculation The percent density retention is calculated by dividing the blue density after bleaching by the original blue density (after treatment, but before bleaching) and multiplying by 100. Make this calculation for all six uniform-density patches. With
41、 some photographic materials, particularly photographic paper prints, bleaching can cause an increase in the D min . The percent density retention shall be corrected for any D min increase, as shown in normative annex D.ISO 18915:2000(E) ISO 2000 All rights reserved 3 4.6 Significance The retained d
42、ensity is an approximation of the percentage of silver image that has been converted into substances which are not affected by oxidants or pollutants. A treatment that results in 65 % density retention or more after bleaching for all six density patches is considered a stable image. NOTE This densit
43、y retention value is based on the fact that since two-thirds of the image will not be affected by oxidants, there would be no loss of information. Treatments that result in a lower percent density retention may also be very stable, depending upon the image density and type of chemical conversion. 5
44、Hydrogen peroxide incubation test 5.1 Principle This test consists of exposing the treated silver images to hydrogen peroxide vapour and measuring the resultant change in density. A small change in density represents an image that is resistant to peroxides. 5.2 Reagents 5.2.1 Hydrogen peroxide, reag
45、ent grade, 2 % (m/m) solution, freshly prepared from a 30 % stock solution. WARNING Hydrogen peroxide is very corrosive. Caution should be used in handling hydrogen peroxide solutions. The stock solutions should be kept refrigerated in vertical vented bottles and kept away from combustibles. Gloves
46、and protective clothing should be worn. Take care to dispose of hydrogen peroxide solutions according to national and local waste disposal regulations. 5.2.2 Potassium chloride, saturated solution. 5.2.3 Potassium chloride, dry solid. 5.3 Apparatus 5.3.1 Glass desiccator jar, having a nominal inside
47、 diameter of 150 mm and a capacity of 2 litres. 5.3.2 Ground plastic desiccator lid 4 ,fi t t edw i t hafa n . The fan motor is attached to the top surface of the desiccator lid with the shaft going through the lid to the fan mounted on the inside surface. There shall be four fan blades, each approx
48、imately 25 mm in length. The fan shall rotate at approximately 2 000 r/min. 5.3.3 Plastic collar 4) , that shall fit snugly inside the desiccator on which the specimens are mounted. The collar shall be roughly 80 mm in height with an inside diameter of 135 mm and a wall thickness of approximately 7
49、mm. The collar shall be fitted with three baffles, each approximately 80 mm in length, 20 mm in depth, and 25 mm in width. NOTE The baffles serve to provide more turbulent air movement and ensure uniform distribution of the hydrogen peroxide vapour. They may be constructed of a hydrogen-peroxide-resistant plastic, such as polycarbonate. 4 Poly(methyl metachrylate) has proven to be an acceptable plastic.ISO 18915:2000(E) 4 ISO 2000 All rights reserved A drawing of the collar
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