RWANDA STANDARD DRS 495-1

RWANDA DRS
STANDARD
 495-1

 First edition

 2022-mm-dd

Organic pigments for paints —

Specification —

Part 1:

Azo pigments

ICS 87.060.10

 Reference number

 DRS 495-1: 2022

 © RSB 2022

DRS 495-1: 2022

 In order to match with technological development and to keep continuous progress in industries,
 standards are subject to periodic review. Users shall ascertain that they are in possession of the latest
 edition

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 in any form or by any means, electronic or mechanical, including photocopying and microfilm, without
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DRS 495-1: 2022

Contents Page

Foreword ............................................................................................................................................................ iv

1 Scope ...................................................................................................................................................... 1

2 Normative references ............................................................................................................................ 1

3 Terms and definitions ........................................................................................................................... 2

4 Requirements ......................................................................................................................................... 2
4.1 General requirements ........................................................................................................................... 2
4.2 Specific requirements ........................................................................................................................... 2

5 Packaging and labelling........................................................................................................................ 3
5.1 Packaging ............................................................................................................................................... 3
5.2 Labelling ................................................................................................................................................. 3

6 Sampling ................................................................................................................................................ 4

Annex A (normative) Determination of sulphated ash .................................................................................. 5
A.1 Procedure ............................................................................................................................................... 5
A.2 Calculation ............................................................................................................................................. 5

Annex B (normative) Determination of resistance to acid, alkali and lime ................................................. 6
B.1 Outline of the method ........................................................................................................................... 6
B.2 Reagents ................................................................................................................................................ 6
B.3 Procedure ............................................................................................................................................... 6

iii ©RSB 2022 - All rights reserved

DRS 495-1: 2022

Foreword

Rwanda Standards are prepared by Technical Committees and approved by Rwanda Standards Board (RSB)
Board of Directors in accordance with the procedures of RSB, in compliance with Annex 3 of the WTO/TBT
agreement on the preparation, adoption and application of standards.

The main task of technical committees is to prepare national standards. Final Draft Rwanda Standards
adopted by Technical committees are ratified by members of RSB Board of Directors for publication and
gazettment as Rwanda Standards.

DRS 495-1 was prepared by Technical Committee RSB/TC 056, Paints, Varnishes, Adhesives and Related
Products.

In the preparation of this standard, reference was made to the following standard:

IS 3574: Specification for organic pigments for paints – Part 1: Azo Pigments (Toluidine red; chlorinated p-
 Nitroaniline red; arylamide yellows; and para red)

The assistance derived from the above source is hereby acknowledged with thanks.

DRS 495 consists of the following parts, under the general title Organic pigments for paints — Specification:

⎯ Part 1: Azo pigments

⎯ Part 2: Phthalocyanines

Committee membership

The following organizations were represented on the Technical Committee on Paint, Varnishes, Adhesives
and related Products (RSB/TC 056) in the preparation of this standard.

University of Rwanda/College of Sciences and Technology (UR/CST)

University of Rwanda/College of Education (UR/CE)

EARTHENABLE

Standards for Sustainability (SfS)

AMACO Paints

Rwanda Inspectorate, Competition and Consumer Protection Authority (RICA)

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DRS 495-1: 2022

REX Paints

Star Construction and Consultancy Ltd

IPRC Kigali

MEI Paints

Rwanda Standards Board (RSB) – Secretariat

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DRS 495-1: 2022

Introduction

Among the most important organic pigments used in paint industry are toluidine red, chlorinated p-nitroaniline
red (commercially known as signal red or permanent red), arylamide yellow G and 10 G (commercially known
as fast yellow or hansa yellow) and to some extent para red. Dinitro-aniline red (permanent orange) is not
included as the production of this pigment has been prohibited. The colour index number of these pigments
are as follows:

 i) Toluidine red – colour index No 12120; C.I. pigment red 3.
 ii) Chlorinated p-nitroaniline red – colour index No 12085; C.I. pigment red 4.
 iii) Arylamide yellow G – colour index No 11680; C.I. pigment yellow 1.
 iv) Arylamide yellow 10 G – colour index No 11710; C.I. pigment yellow 3.
 v) Para red – colour index No 12070; C.I. pigment red 1.

Toluidine reds may differ in mass tone. The most office red colour characteristically produced by this pigment
is obtained by using either a single pigment or more often by a blend of two or more pigments. The blending of
toluidine reds of varying mass tones is usually necessary in order to get a close match to Indian Standard
Colour No 538 of IS 5-1961.

Unlike toluidine reds, chlorinated p-nitroaniline red is usually produced in order to get a close match to IS
Colour No 537 of IS 5-1961, directly without further bending. Sometimes, manufacturers of chlorinated p-
nitroaniline red in two mass tones, namely one a little lighter and the other a little deeper in colour to IS Colour
No 537 of IS 5-1961. A judicious blending of these two results in a close match to the standard colour desired.

Arylamide yellow G and 10 G differ in mass tones (G denotes pure yellow and 10 G denotes greenish yellow).
A suitable blend of arylamide yellow G and 10 G will produce arylamide yellow 3G and arylamide yellow 7G.

Para red is usually produced only in one mass tone and used in cheaper type of paints on account of its lower
cost.

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DRS 495-1: 2022

Organic pigments for paints — Specification — Part 1: Azo Pigments

1 Scope

This Draft Rwanda Standard specifies the requirements, sampling and test methods for five (5) organic
pigments, namely, toluidine red, chlorinated p-nitroaniline red, arylamide yellow G and 10 G and para red
used in paint industry.

2 Normative references

The following documents are referred to in the text in such a way that some or all of their content constitutes
requirements of this document. For dated references, only the edition cited applies. For undated references,
the latest edition of the referenced document (including any amendments) applies.

ISO 18451-1, Pigments, dyestuffs and extenders — Terminology — Part 1: General terms

ISO 18451-2, Pigments, dyestuffs and extenders — Terminology — Part 2: Classification of colouring
materials according to colouristic and chemical aspects

ISO 787-7, General methods of test for pigments and extenders — Part 7: Determination of residue on sieve
— Water method — Manual procedure

ISO 787-2, General methods of test for pigments and extenders — Part 2: Determination of matter volatile at
105 degrees C

ISO 787-3, General methods of test for pigments and extenders — Part 3: Determination of matter soluble in
water — Hot extraction method

ISO 787-5, General methods of test for pigments and extenders — Part 5: Determination of oil absorption
value

ISO 787-25, General methods of test for pigments and extenders — Part 25: Comparison of the colour, in full-
shade systems, of white, black and coloured pigments — Colorimetric method

ISO 787-16, General methods of test for pigments and extenders — Part 16: Determination of relative tinting
strength (or equivalent colouring value) and colour on reduction of coloured pigments — Visual comparison
method

ISO 787-15, General methods of test for pigments and extenders — Part 15: Comparison of resistance to light
of coloured pigments of similar types

ISO 787-22, General methods of test for pigments and extenders — Part 22: Comparison of resistance to
bleeding of pigments

1 ©RSB 2022 - All rights reserved

ISO 787-21, General methods of test for pigments and extenders — Part 21: Comparison of heat stability of
pigments using a stoving medium

RS OIML R 87, Quantity of product in pre-packages

ISO 15528, Paints, varnishes and raw materials for paints and varnishes — Sampling

3 Terms and definitions

For the purposes of this standard, the terms and definitions given in ISO 18451-1, ISO 18451-2 and the
following apply.

3.1

term

text of the definition

4 Requirements

4.1 General requirements

4.1.1 The pigment shall be in the form of a fine, dry, soft powder or in such a condition that it can be readily
reduced to the powder form by crushing under a palette knife, without grinding action

4.1.2 The pigment shall be free from grit.

4.2 Specific requirements

The pigments shall comply with the requirements given in table 1 when tested in accordance with the methods
prescribed therein.

 Table 1 — Specific requirements for Azo Pigments
 S/N Parameters Requirements Test methods
 1 Residue on sieve, % by mass, max. 0.5 ISO 787-7
 Toluidine red 2.5
 Chlorinated p-
 2.5
 nitroaniline red
 Sulphated ash, % by
 2 Annex A
 mass, max. Arylamide yellow G 3.5
 Arylamide yellow 10 G 3.5
 Para red 10.0
 3 Matter volatile at 100 ˚C, % by mass, max. 1.0 ISO 787-2
 4 Matter soluble in water, % by mass, max. 1.0 ISO 787-3
 5 Oil absorption values 1 Toluidine red 35 – 65 ISO 787-5

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DRS 495-1: 2022

 Chlorinated p-
 45 – 65
 nitroaniline red
 Arylamide yellow G 40 – 60
 Arylamide yellow 10 G 40 – 60
 Para red 35 – 65
 Colour Close match to the
 6 ISO 787-25
 approved sample
 7 Staining power and colour on reduction Do ISO 787-16
 Fastness to light Not inferior to the
 8 ISO 787-15
 approved sample
 10 Bleeding Do ISO 787-22
 11 Heat stability Do ISO 787-21
 12 Resistance to acids and alkalis Do Annex B
 1 The value of oil absorption shall be within ± 5% of the approved sample, if any.

5 Packaging and labelling

5.1 Packaging

6.1.1 The pigment shall be packaged in a suitable container that prevents it from deterioration during
storage, transportation and normal handling.

6.1.2 The quantity of product packaged in a container shall be in accordance with the requirements of RS
OIML R 87.

5.2 Labelling

6.2.1 Each container shall be labelled legibly and indelibly with the following information in any of the three
languages officially accepted in the Republic of Rwanda namely: Kinyarwanda, French and English:

a) name of the product;

b) name and address of the manufacturer and/or registered trader mark;

c) net content;

d) organic/inorganic colouring matter, % by mass, if added;

e) batch number

f) manufacture and expiry dates;

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g) instructions for use and disposal;

h) special precautions, if any; and

i) storage condition

6 Sampling

Sampling shall be done in accordance with RS ISO 15528.

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DRS 495-1: 2022

 Annex A
 (normative)

 Determination of sulphated ash

A.1 Procedure

Cool a previously ignited and weighed crucible in a desiccator and weigh accurately into it about 2 g of the test
sample. Heat gently i the flame of a Bunsen burner until burning and charring is complete. Moisten with a few
drops of concentrated sulphuric acid and heat gently until fuming ceases. Ignite strongly and cool in a
desiccator. Repeat ignition until constant mass is obtained.

A.2 Calculation

 ( 1− 2)
Matter volatile, % by mass = 100 1

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Annex B
 (normative)

 Determination of resistance to acid, alkali and lime

B.1 Outline of the method

Resistance to acid, alkali and lime is determined by finding out the degree of bleeding of the solutions
prepared from material under test and the approved sample in hydrochloric acid, sodium hydroxide and
calcium hydroxide solution respectively. Additionally, the treated pigment is washed, dried and tested against
pigment for full colour and reduction.

B.2 Reagents

B.2.1 Standard Hydrochloric Acid – 0.5 N

B.2.2 Standard Sodium Hydroxide Solution – 0.25

B.2.3 Calcium Hydroxide Solution – 10%

B.3 Procedure

B.3.1 Resistance to acid – Take about 1g of the pigment in a 100-mL flask and shake with about 50 mL of
standard hydrochloric acid. Allow the contents to stand for one hour. In another flask treat an equal quantity of
the approved sample in a similar manner. Note the colour change in the supernatant liquid of the material
under test as compared with that of the approved sample. Wash the pigment free from acid, filter and dry in an
oven at 100 ± 2 ˚C. Determine the change in colour and staining power of the pigment. Compare the change
in the test sample with that obtained in the case of the approved sample, when similarly treated and tested.

B.3.2 Resistance to lime – Repeat the above test (see B.3.1) but using calcium hydroxide solution in
place of standard hydrochloric acid.

B.3.3 Resistance to alkali – Repeat the above test (see B.3.1) but using standard sodium hydroxide
solution in place of hydrochloric acid.

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DRS 495-1: 2022

 Bibliography

[1] IS 3493, Method of sampling and test for organic pigments for paints, 1978

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DRS 495-1: 2022

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