ISO 3624:1994

INTERNATIONAL
ISO
STANDARD
3624
Second edition
1994-11-01
Photography - Processing chemicals -
Specifications for potassium ferricyanide
Photographie - Produits chimiques de traitemen t - Spkifica tions pour Ie
ferricyanure de po tassium
Weference nurnber
OS0 3624:1994(E)

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ISO 3624: 1994(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
technical committees. Esch 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. 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
a vote.
International Standard ISO 3624 was prepared by Technical Committee
lSO/TC 42, Photography.
This second edition cancels and replaces the first edition (ISO 3624:i 976)
which has been technically revised.
0 ISO 1994
All rights reserved. Unless otherwise specified, no part of this publication may be reproduced
or utilized in any form or by any means, electronie or mechanical, including photocopyrng and
mrcrofilm, without Permission in writing from the publisher.
International Organization for Standardization
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Printed in Switzerland
ii

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0 ISO
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 ISO 10349-1.
This International Standard is intended for use by individuals with a
working knowledge of analytical techniques which is possibly not always
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
should 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.
0.2 This International Standard provides Chemical and physical require-
ments for the suitability of a photographit-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.

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ISO 3624: 1994(E) 0 ISO
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
tests which require highly specialized equipment or techniques.
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. Correlatio
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