ISO 3629:1996
(Main)Photography — Processing chemicals — Specifications for potassium metabisulfite
Photography — Processing chemicals — Specifications for potassium metabisulfite
Photographie — Produits chimiques de traitement — Spécifications pour le potassium métabisulfite
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Standards Content (Sample)
INTERNATIONAL
STANDARD
Second edition
1996-l O-l 5
Photography - Processing chemicals -
Specifications for potassium metabisulfite
Photographie - Produits chimiques de traitement - Spkifications
relatives au mgtabisulfite de potassium
Reference number
IS0 3629:1996(E)
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IS0 3629: 1996(E)
Foreword
IS0 (the International Organization for Standardization) is a worldwide
federation of national standards bodies (IS0 member bodies). The work of
preparing International Standards is normally carried out through IS0
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. IS0
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
a vote.
International Standard IS0 3629 was prepared by Technical Committee
ISO/TC 42, Photography.
This second edition cancels and replaces the first edition (IS0 3629:I 976),
which has been technically revised.
0 IS0 1996
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 the publisher.
International Organization for Standardization
Case Postale 56 l CH-1211 Geneve 20 l Switzerland
Printed in Switzerland
II
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@ IS0 lSO3629:1996(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 9 of IS0 10349.
This International Standard is intended for use by individuals with a
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
the use of safety glasses or goggles, rubber gloves and other protective
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 IS0 10349-I. More detailed
information regarding hazards, handling and use of these chemicals may
be available from the manufacturer.
0.2 This International Standard provides chemical 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. Although 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 a
safeguard of chemical .purity but also as a valuable complement to the
identity test. Identity tests have been included whenever a possibility
exists that another chemical or mixture of chemicals could pass the other
tests.
All requirements listed in clause 4 are mandatory. The physical appearance
of the material and any footnotes are for general information only and are
not part of the requirements.
Ill
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0 IS0
IS0 3629: 1996(E)
0.3 Efforts have been made to employ tests which are capable of being
run in any normally equipped laboratory and, wherever possible, to avoid
highly specialized equipment or techniques.
tests which require
Instrumental methods have been specified only as alternative methods or
alone in those cases where no other satisfactory method is available.
Over the past few years, great improvements have been made in
instrumentation for various analyses. Where such techniques have
equivalent or greater precision, they may be used in place of the tests
described in this International Standard. Correlation of such alternative
procedures with the given method is the responsibility of the user. In case
of disagreement in results, the method called for in the specification shall
prevail. Where a requirement states “to pass test”, however, alternative
methods shall not be used.
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INTERNATIONAL STANDARD @ IS0 IS0 3629: 1996(E)
Photography - Processing chemicals - Specifications for
potassium metabisulfite
1 Scope
This International Standard estabfishes criteria for the purity of photographic-grade potassium metabisulfite and
specifies the test methods to be used to determine the purity.
2 Normative references
The following standards contain provisions which, through reference in this text, constitute provisions of this
International Standard. At the time of publication, the editions indicated were valid. All standards are subject to
revision, and parties to agreements based on this International Standard are encouraged to investigate the
possibility of applying the most recent editions of the standards indicated below. Members of IEC and IS0 maintain
registers of currently valid International Standards.
IS0 10349-I : 1992, Photography - Photographic-grade chemicals - Test methods - Part 7 . * General .
IS0 10349-5: 1992, Photography - Photographic-grade chemicals - Test methods - Part 5. . Determination of
heavy metals and iron content.
IS0 10349-g: 1992, Photography - Photographic-grade chemicals - Test methods - Part 9. . Reaction to
ammoniacal silver nitrate.
3 General
3.1 Physical properties
Potassium metabisulfite (K&05) exists in the form of white, glassy crystals. It has a relative molecular mass of
222,33.
3.2 Hazardous properties
Potassium metabisulfite is not hazardous when handled with normal precautions. Potassium metabisulfite is toxic if
ingested. Avoid contact with acids.
3.3 Storage
Potassium metabisulfite shall be stored in a closed container at room temperature.
1
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IS0 3629: 1996(E)
4 Requirements
A summary of the requirements is shown in table 1.
5 Reagents and glassware
All reagents, materials and glassware shall conform to the requirements specified in IS0 10349-I unless otherwise
noted. The hazard warning symbols used as a reminder in those steps detailing handling operations are defined in
IS0 10349-I. These symbols are used to provide information to the user and are not meant to provide
conformance with hazardous labelling requirements as these vary from country to country.
6 Sampling
See IS0 10349-I.
7 Test methods
7.1 Assay
7.1 .I Specification
Content of potassium metabisulfite shall be 95,0 % (m/m) min.
7.1.2 Reagents
7.1.2.1 Acetic acid (CH$OOH), approx. 2 mol/l solution.
Dilute 120 g of glacial acetic acid (DANGER: (C)(S)) 1) to 1 000 ml.
7.1.2.2 Neutral formaldehyde (HCHO), approx. 37 % (360 g/l) solution (DANGER: (B)(C)(S)).
Adjust the pH of formaldeh
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