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IS0
I NT ERN AT I ON AL ORGAN I Z AT1 O N FOR STAND A RD I ZAT I O N
IS0 RECOMMENDATION
R 591
TITANIUM DIOXIDE FOR PAINTS
1st EDITION
July 1967
COPYRIGHT RESERVED
The copyright of IS0 Recommendations and IS0 Standards
belongs to IS0 Member Bodies. Reproduction of these
documents, in any country, may be authorized therefore only
by the national standards organization of that country, being
a member of ISO.
For each individual country the only valid standard is the national standard of that country.
Printed in Switzerland
Also issued in French and Russian. Copies to be obtained through the national standards organizations.
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BRIEF HISTORY
The IS0 Recommendation R 591, Titanium Dioxide for Paints, was drawn up by Technical
Committee ISO/TC 35, Paints, Varnishes and related Products and their Raw Materials, the
Secretariat of which is held by the Stichting Nederlands Normalisatie-instituut ("1).
Work on this question by the Technical Committee began in 1950 and led, in 1963, to the
adoption of a Draft IS0 Recommendation.
In April 1965, this Draft IS0 Recommendation (No. 798) was circulated to all the IS0
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Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial
nature, by the following Member Bodies:
Argentina Germany Net herlands
Austria India Portugal
Brazil Ireland Spain
Canada Israel Sweden
Chile Italy Turkey
Czechoslovakia Japan U.A.R.
Denmark Korea, Rep. of United Kingdom
France Morocco Yugoslavia
No Member Body opposed the approval of the Draft.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council,
which decided, in July 1967, to accept it as an IS0 RECOMMENDATION.
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ISQ/R 591 - 1967 (E)
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IS0 Recommendation R 591
July 1967
TITANlUM DIOXIDE FOR PAINTS
1. SCOPE
This IS0 Recommendation relates to titanium dioxide pigments, for use in paints, of the following
types :
Type A - Anatase type titanium dioxide,
Type R - Rutile type titanium dioxide.
2. DESCRIPTION
2.1
Type A - Anatase type titanium dioxide
The material should consist essentially of titanium dioxide (TiO,) of the anatase crystal
structure as determined by X-ray examination or, as an indication only, by the determination
of relative density.
The relative density of pure titanium dioxide of anatase crystal structure is 3.9, but most
commercial pigments have densities lower than this. The material should be in the form of
a soft dry powder or in such a condition that it may be readily reduced thereto by crushing
under a palette knife, without any grinding action.
2.2
Type R - Rutile type titanium dioxide
The material should consist essentially of titanium dioxide (TiO,) of the rutile crystal struc-
ture as determined by X-ray examination or, as an indication only, by the determination of
relative density.
The relative density of pure titanium dioxide of rutile crystal structure is 4.2, but most com-
mercial pigments have densities lower than this. The material should be in the form of a
soft dry powder or in such a condition that it may be readily reduced thereto by crushing
under a palette knife, without any grinding action.
3. REQUIRED CHARACTERISTICS AND THEIR TOLERANCES
Both types of titanium dioxide should have the following characteristics :
TABLE
describing
Clause
Characteristics Requirements
test method
Titanium dioxide content % min. 90 I 5. I
Colour Equal to that of an agreed reference
1 5.2
sample
Lightening power Equal to that of an agreed reference
5.3
sample
Matter volatile at 105 OC X max. 0.75 5.4
Matter soluble in water max. 0.5, or not more than that of the
5.5
agreed reference sample
Acidity or alkalinity of the aqueous 20 ml of 0.1 N solution per 100 g
5.6
extract, max. of pigment
Oil absorption value, grammes per Within 10% of that of an agreed
100 g of pigment reference sample or, alternatively, 5.7
between 12 and 35 g
Residue on sieve (63 pm) ”/, max. o. 1 I 5.8
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ISO/R 591 - 1967 (E)
4. SAMPLING
See IS0 Recommendation R . . . *, Sampling Raw Materials for Paints and Varnishes.
5. METHODS OF TEST
5.1 Determination of titanium dioxide content
5.1.1 Interferences. Chromium, vanadium, molybdenum and niobium impurities may
affect the results of this determination; these impurities may be present in commercial
pigments, but normally in very small quantities only.
5.1.2 Reagents. All reagents should be of analytical quality. The water used should be
distilled water or water of equal purity.
5.1.2.1 Ammonium sulphate.
5.1.2.2 Carbon dioxide or nitrogen.
5.1.2.3 Sulphuric acid, concentrated (d = 1.84).
5.1.2.4 Sulphuric acid, 40 g per litre.
5.1.2.5 Sulphuric acid, 20 g per litre.
5.1.2.6 Zinc amalgam, 3 % m/m prepared as below:
Place 50 ml of mercury in a small porcelain dish on a steam bath, covering the
surface of the mercury with sulphuric acid (5.1.2.5). Add 21 g of zinc in small
granules. Stir from time to time and replenish the dilute acid with water as required.
When all the solid zinc has disappeared, allow the amalgam to cool and stand for
sev
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