ISO INTERNATIONAL STANDARD 3626 Second edition 1996-10-15 Photography - Processing chemicals - Specificationsforpotassiumthiocyanate Photographie-Produits chimiques de traitement-Spécifications relativesauthiocyanatedepotassium ISO Referencenumber ISO3626:1996(E) ISO3626:1996(E) 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 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 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 avote. International Standard ISO 3626 was prepared by Technical Committee ISO/TC 42, Photography. This second edition cancels and replaces the first edition (IS0 3626:1976), whichhasbeentechnicallyrevised @ISO1996 All rights reserved. Unless otherwise specified, no part of this publication may be photocopying and microfilm, without permission in writing from the publisher. International OrganizationforStandardization Case Postale 56.CH-1211 Geneve 20·Switzerland Printed in Switzerland ii C ISO ISO3626:1996(E) Introduction 0.1 This International Standard is one of a series that establishes criteria of purity for chemicals used in processing photographic materials. General test methods and procedures cited in this International Standard are compiled in parts 1, 5 and 6 of ISO 10349. This International Standard is intended for use by individuals switha working knowledge of analytical techniques, which may not always be the case. Some of the procedures utilize caustic, toxic or otherwise hazardous chemicals. Safe laboratory practice for the handling of chemicals requires apparel such as face masks or aprons where appropriate. Normal precautions required in the performance of any chemical procedure are to be exercised at all times but care has been taken to provide warnings for hazardous materials. Hazard warnings designated by a letter enclosed in angle brackets "< >" are used as a reminder in those steps detailing handling, operations and are defined in ISO 10349-1. More detailed information regarding hazards, handling and use of these chemicals may be available from the manufacturer. 0.2This International Standard provideschemical and physical requirements for the suitability of a photographic-grade chemical. The tests correlate with undesirable photographic effects. Purity requirements are set as low as possible consistent with these photographic effects. These criteria are considered the minimum requirements necessary to assure sufficient purity for use in photographic processing solutions, except that if the purity of a commonly available grade of chemical exceeds photographic processing requirements and if there is no economic penalty in its use, the purity requirements have been set to take advantage of the availability of the higher-quality material. Every effort has been made to keep the number of requirements to a minimum. Inert impurities are limited to amounts which will not unduly reduce the assay. All tests are performed on samples "as received" to reflect the condition of materials furnished for use. Aithough the ultimate criterion for suitability of such a chemical is its successful performance in an appropriate use test, the shorter, more economical test methods described in this International Standard are generally adequate. Assay procedures have been included in all cases where a satisfactory method is available. An effective assay requirement serves not only as