ISO 3624:1994

Photography - Processing chemicals - Specifications for potassium ferricyanide

Cancels and replaces the first edition (1976). Lays down criteria for the purity of photographic-grade potassium ferricyanide and describes the tests to be used to determine the purity.

Photographie — Produits chimiques de traitement — Spécifications pour le ferricyanure de potassium

General Information

• Status: Published
• Publication Date: 12-Oct-1994
• ICS: 37.040.30 - Photographic chemicals
• Technical Committee: ISO/TC 42 - Photography
• Drafting Committee: ISO/TC 42 - Photography
• Current Stage: 9093 - International Standard confirmed
• Start Date: 05-Jun-2021
• Completion Date: 13-Dec-2025

Relations

• Revises: ISO 3624:1976 - Photographic grade potassium ferricyanide - Specification
• Effective Date: 15-Apr-2008

Overview

ISO 3624:1994 is an international standard established by the International Organization for Standardization (ISO) that defines the specifications and purity criteria for photographic-grade potassium ferricyanide. This second edition, published in 1994, cancels and replaces the original 1976 version. It provides detailed guidelines for the chemical’s physical and chemical properties, focusing on ensuring its suitability in photographic processing chemicals.

The standard outlines test methods to determine the purity and quality of potassium ferricyanide, emphasizing safety measures for handling this moderately toxic chemical. It is an essential reference for manufacturers, quality control laboratories, and photographic chemical users who require consistent and reliable chemicals for developing photographic materials.

Key Topics

• Purity Requirements: The potassium ferricyanide used in photographic processing must meet a minimum assay of 99.0% (mass/mass) to ensure high-quality photographic results. The standard sets limits on inert impurities that might affect chemical performance.

• Test Methods: ISO 3624 specifies analytical procedures for verifying the purity of potassium ferricyanide. This includes titration with sodium thiosulfate using potassium iodide and zinc sulfate reagents, supported by visual inspections for clarity and the absence of insoluble matter.

• Physical Properties: The chemical appears as red crystals or crystalline powder and must dissolve in water to form a clear solution, free from insoluble impurities aside from minimal flocculence.

• Safety and Handling: Due to its moderate toxicity and potential to emit highly toxic cyanide fumes when heated or exposed to acid, strict safety protocols are recommended. The use of protective equipment like safety glasses, gloves, and proper ventilation is advised.

• Sampling and Compliance: The standard recommends sample collection procedures and notes that all tests should be conducted on the material "as received" to accurately reflect supplier quality.

Applications

ISO 3624:1994 is primarily used in the photographic industry where potassium ferricyanide serves as a processing chemical. Its applications include:

• Photographic Film and Paper Processing: Potassium ferricyanide is key for bleaching and toning photographic materials, influencing image quality and archival stability.

• Quality Control: Laboratories use the standard test methods to verify chemical purity before use in production, ensuring consistent photographic processing outcomes.

• Chemical Manufacturing: Producers of photographic chemicals apply the ISO specifications to formulate and guarantee the purity of their potassium ferricyanide products.

• Research and Development: Organizations developing new photographic processes or chemicals rely on the standard for benchmarking chemical specifications and conducting analytical assessments.

Related Standards

ISO 3624 references several crucial standards relevant to photographic chemical testing and safety:

• ISO 10349-1: General test methods and procedures for photographic-grade chemicals, providing guidance on laboratory techniques, reagent standards, and hazard warnings relevant to ISO 3624 testing.

• ISO/TC 42 (Photography Technical Committee): The ISO committee responsible for developing standards related to photography, including chemical specifications and testing methods.

Additional national or international standards concerning handling hazardous materials and laboratory safety should complement ISO 3624 compliance to ensure safe usage and environmental protection.

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Keywords

ISO 3624, potassium ferricyanide specifications, photographic chemicals standard, potassium ferricyanide purity, photographic processing chemicals, chemical assay methods, ISO photography standards, photographic chemical quality control, potassium ferricyanide safety, photographic-grade chemicals

Standards Content (Sample)

INTERNATIONAL
ISO
STANDARD
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)
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
Case postale 56 l CH-l 211 Geneve 20 l Switzerland
Printed in Switzerland
ii
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.
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
...