ISO INTERNATIONAL STANDARD 423 Second edition 1994-05-01 Photography Processing chemicals - Specifications for hydroquinone Photographie - Produits chimiques pour traitement - Spécifications relativesaT'hydroquinone ISO Reference number SO423:1994(E) No reproduction or networking permited without license from IHS Not for Resale ISO 423:1994(E) Foreword ISO (the International Organization for Standardization) is a worldwide of preparing International Standards is normally carried out through IsO 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. 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 423 was prepared by Technical Committee ISO/TC 42,Photography. This second edition cancels and replaces the first edition (iSO 423:1976) which has been technically revised. AnnexAofthisInternationalStandardisforinformationonly ISO1994 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced microfilm, without permission in writing from the publisher International Organizationfor Standardization Case Postale 56 . CH-1211 Geneve 20 : Switzerland Printed in Switzerland Copyright Intenational Organization for Standardization No reproduction or networking pemited without license from IHS Not fr Resale ISO ISO 423:1994(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, 4 and 5 of Is0 10349. This International Standard is intended for use by individuals with a work- case. Some of the procedures utilize caustic, toxic or otherwise hazardous chemicals. Safe laboratory practice for the handling of chemicals requires the use of safety glasses or goggles, rubber gloves and other protective apparel such as face masks or aprons where appropriate. Normal pre- 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 hand- ling operations and are defined in ISO 10349-1. More detailed information regarding hazards, handing and use of these chemicals may be available fromthe manufacturer. o.2 This International Standard provides chemical and physical require- ments for the suitability of a photographic-grade chemical. The tests cor- relate with undesirable photographic effects. Purity requirements are set as low as possible consistent with these photographic effects. These cri- teria are considered the minimum requirements necessary to assure suf- the purity of a commonly available grade of chemical exceeds photo- graphic processing requirements and if there is no economic penalty in its use, the purity requirements have been set to take advantage of the keep the number of requirements to a minimum. Inert impurities are lim- ited to amounts which will not unduly reduce the assay. All tests are per- 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. method is available. An effective assay requirement serves not only as a safeguard of chemical purity but also as a valuable complement to the identity test. ldentity tests have been included whenever a possibility ex- ists that another chemical or mixture of chemicals could pass the other tests. ii Not for Resale