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First series
IS0
FOR STAN DA RD I2 AT1 ON
I NT ERN AT1 ON A L ORGAN IZATl O N
IS0 RECOMMENDATION
R 787
GENERAL METHODS OF TEST FOR PIGMENTS
FIRST SERIES
I 50 U\
1st EDITION
July 1968
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
relating to the First Series
The IS0 Recommendation R 787, General methods of test for pigments, was drawn up by
Technical Committee ISO/TC 35, Paints, varnishes and related products and their raw matmals,
the Secretariat of which is held by the Nederlands Normalisatie-institut ("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 October 1965, this Draft IS0 Recommendation (No. 832) was circulated to all the IS0
Member Bodies for enquiry. It was approved, subject to a few modifications of an editorial nature, by
the following Member Bodies :
Argentina Czechoslovakia Spain
Australia India Switzerland
Austria Iran U.A.R.
Belgium Ireland United Kingdom
Brazil Israel U.S.S.R.
Canada Japan Yugoslavia
Chile Netherlands
Colombia Portugal
In addition, the Member Body of Denmark disapproved Part 2, the Member Body of France
disapproved Part 1, the Member Body of Italy disapproved Parts 6 and 7 and the Member Body of
Sweden disapproved Part 4.
The Draft IS0 Recommendation was then submitted by correspondence to the IS0 Council
which decided, in July 1968, to accept it as an IS0 RECOMMENDATION.
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FOREWORD
The purpose of this IS0 Recommendation is to establish a series of general test methods for pigments
which are suitable for all or many of the individual pigments for which specifications might be .
required. In such cases, a cross-reference to the general method should be included in the IS0 Recom-
mendation relating to that pigment, with a note of any detailed modifications which might be needed
in view of the special properties of the pigment in question.
Committee ISO/TC 35 decided that all the general methods should be published in convenient
groups as they become available, as parts of a single IS0 Recommendation, in order to emphasize the
relationship of each to the whole series.
The Committee also decided that, where two or more procedures were widely used for determining
t.
the same or a similar characteristic of a pigment, there would be no objection to including more than
one of them in the IS0 series. In such cases it will, however, be essential to state clearly in a
specification which method is to be used, and in the test report, which method has been used.
CONTENTS
Page
1. Part1 : Comparison of colour . 5
2. Part II : Determination of matter volatile at 105 "C . . 9
L 3. Part III : Determination of matter soluble in water
(Hot extraction method) . 11
4. Part IV : Determination of acidity or alkalinity of the
aqueous extract .
13
5. Part V : Determination of oil absorption value .
15
6. Part VI : Determination of residue on sieve
(Oil method) .
19
7. Part VI1 : Determination of residue on sieve
(Water method) . 21
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ISO/R 787/1-1968 (E
July 1968
IS0 Recommendation R 787
GENERAL METHODS OF TEST FOR PIGMENTS
PART I
COMPARISON OF COLOUR
INTRODUCTION
This document is a part of ISO/R 787, General methods of test forpigments.
1. SCOPE
1.1
Part I of this IS0 Recommendation describes a general method of test for comparing the colour
of a coloured pigment with that of an agreed sample of the pigment.
1.2
Either of the procedures described in section 5 is acceptable, but whenever an automatic muller
is available, its use is recommended.
NOTE. - When this general method is applicable to a given pigment, only a cross-reference to it need be
included in the IS0 Recommendation relating to that pigment, with a note of any detailed modification
which may be needed in view of the special properties of the pigment in question. Only when this general
method is not applicable to a particular pigment should a special method for comparison of colour be
specified.
2. REAGENT
2.1 Refined linseed oil, complying with IS0 Recommendation R 150, Raw, refined and boiled
linseed oil, and having an acid value of 5.0 to 7.0 mg of KOH per gramme.
3. APPARATUS
3.1 Palette knife, steel knife with a tapered blade of the approximate dimensions 140 to 150 mm
long, 20 to 25 mm wide at its widest point and not less than 12.5 mm wide at its narrowest
point.
3.2
Glass slide, clear and colourless, 150 mm X 50 mm or other suitable size.
3.3 Burette, with a delivery such that 35 drops equal 1 ml of refmed linseed oil.
3.4 Automatic muller, plates with a diameter of about 20 cm, speed of rotation about 120 rev/min.
Alternatively, there may be used either a hand muller with a diameter of 70 to 75 mmor a
palette knife complying with clause 3.1.
3.5 Plate, of grounddass or marble, for use when an automatic muller is not available.
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lSOlR 78711-1968 (E
4. SAMPLING
The sample of pigment used for the test should be taken in accordance with the provisions of IS0
Recommendation R 842, Sampling raw materials for paints and varnishes.
5. PROCEDURE
5.1 Test portion
The quantity of pigment taken for the test should be that indicated in the Table below, the oil
absorption value of the pigment having been determined in accordance with Part V of this
IS0 Recommendation.
TABLE
Oil absorption value of pigment
Mass of the test portion
mi/ 1 oog
g
25 or less
1 26 to 65 1 1
66 upward
5.2 Procedure using automatic mulier
Weigh, to the nearest milligramme, the amount indicated in the Table above O .e pigment
under test, and transfer it-to the clean lower plate of the automatic muller (3.4). Add by
means of the palette knife blade (3.1) the number of drops of refined linseed oil sufficient to
obtain a satisfactory dispersion so that, when mixed, a smooth pigment-oil paste is obtained.
When the pigment has been wetted, spread the paste in a circle of approximately 50 mm in
diameter around the centre of the lower plate and clean the palette knife by drawing it across
the top plate. Close the muller plates, apply a pressure of 68 kgf and grind the paste in four
stages of fifty revolutions for each stage, picking up the paste with the same palette knife and
transferring it to the centre of the plate after each stage.
When the grinding has been completed, add a further number of drops of the oil sufficient to
obtain a suitable painting consistency, close the muller plates and grind the paste for a further
twenty-five revolutions, then remove the paint from the plate and store it on a palette.
Prepare a paint immediately from the agreed sample of the pigment, using the same procedure.
Compare the colour of the test portion with that of the agreed sample by spreading the two
mixtures so prepared in the same direction on the giass slide (3.2) in opaque strips not less than
25 mm wide with touching edges not less than 40 mm long. Make the colour comparison by
examining the strips in diffused daylight through the giass, and on the surface, immediately
after application. Where good daylight is not available make the comparison in artifical daylight.
By agreement between purchaser and vendor, a suitable colorimeter may also be used for
making the comparison.
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ISO/R 78711-1968 (E)
5.3 Procedure using hand muller or palette knife
Weigh, to the nearest milligramme, the amount indicated in the Table of the pigment under test,
and transfer it to the glass or marble plate (3.5). Collect, on the end of the palette knife (3.1),
the number of drops of oil sufficient to obtain a suitable consistency for spreading out with the
palette knife, and mix it with the pigment on the plate (3.5).
When the pigment has become uniformly wetted with oil, start rubbing with the palette knife
(3.1) or hand muller (3.4), using a backwards and forwards motion. Rubbing should spread the
mixture over an area approximately 200 mm X 75 mm. After one hundred rubs (one rub
consists of one forward plus one backward stroke of the knife), scrape the pigment-oil mixture
into a heap at the centre of the plate, making sure that any unground pigment is removed from
the knife blade outside the area which has been in contact with the plate.
Repeat the rubbing-out operation using a further hundred rubs; after which add a further number
of drops of oil sufficient to obtain a suitable painting consistency. Mix well until the mixture is
homogeneous, then transfer the mixture to one corner of the plate and clean the rest of the
plate thoroughly.
Rub out the agreed sample of the pigment in the same way, using the same rubbing consistency
as that used in treating the test portion, even though this may involve adding a larger or smaller
number of drops of oil than used with the test portion to bring the agreed sample to the
required consistency.
NOTE. - In each case, a total of between ten and forty-five drops of oil will be required to produce a con-
sistency which allows the mixture to be painted out.
Compare, as described in clause 5.2, the colour of the test portion with that of the agreed
sample of the pigment.
6. TEST REPORT
The test report should include the following information :
A reference to IS0 Recommendation R 787, Part I, or to a corresponding national
(U)
standard.
Type and identification of the pigment under test.
(b)
Any deviation, by agreement or otherwise, from the test procedures described above.
(c)
The procedure used (automatic muller, hand muller or palette knife).
(d)
The result of the test (equal to, or better or worse than, the agreed sample of pigment).
(e)
The date of the test.
U>
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ISOlR 787111-1968 (E
I SO Recommendation R 787 July 1968
GENERAL METHODS OF TEST FOR PIGMENTS
PART II
DETERMINATION OF MATTER VOLATILE AT 105" C
INTRODUCTION
This document is a part of ISO/R 787, General methods of test for pigments.
1. SCOPE
Part II of this IS0 Recommendation describes a general method of test for determining the percentage
by mass of matter volatile at a temperature of 105 OC, in a sample of pigment.
NOTE. - When this general method is applicable to a given pigment, only a cross-reference to it need be included in
the IS0 Recommendation relating to that pigment, with a note of any detailed modification which may be needed in
view of the special properties of the pigment in question. Only when this general method is not applicable to a
particular pigment should a special method for determination of volatile matter be specified.
2. APPARATUS
2.1 Weighing bottle, short, wide-mouthed, with ground-glass stopper.
2.2 Oven, capable of being maintained at a temperature of 105 I2 OC.
2.3 Balance, sensitivity 1 mg.
2.4 Desiccator.
3. SAMPLING
The sample of pigment used for the test should be taken in accordance with the provisions of IS0
Recommendation R 842, Sampling raw materials for paints and varnishes.
4. PROCEDURE
4.1 Test portion
Spread 10 k 1 g of the pigment under test in a uniform layer on the bottom of the tared
weighing bottle (2.1), insert the stopper and weigh to the nearest milligramme.
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ISO/R 787/11-1968 (E)
4.2 Determination
Heat the weighing bottle (2.1) and contents, with the stopper removed, in an oven at a tempera-
ture of 105 f 2 OC. Cool the bottle in the desiccator to room temperature, insert the stopper
and weigh to the nearest milligramme.
Repeat the heating and cooling until constant mass is attained, i.e. until the results of two
successive weighmgs, at an interval including at least 30 minutes heating, do not differ by
more than 5 mg.
NOTE. - If the pigment under test is unstable at a temperature of 105 OC, the testing conditions should be
agreed between purchaser and vendor and indicated in the test report.
5. EXPRESSION OF RESULTS
Calculate the matter volatile at a temperature of 105 OC, in percentage .>ss by mass, i.e.
100(m-m,)
m
where
m is the original mass, in grammes, of the test portion,
is the final mass, in grammes, of the test portion after heating.
mi
0.1
Report the result to the nearest
6. TEST REPORT
The test report should include the foilowing information :
A reference to IS0 Recommendation R 787, =drt II, or to a corresponding nationa
(a)
standard.
Type and identification of the pigment under test.
(b)
Any deviation, by agreement or otherwise, from the test procedures described above.
(e)
The result of the test as indicated in section 5.
(d)
The date of the test.
(e)
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ISO/R 787/111-1968 (E)
IS0 Recommendation R 787 July 1968
GENERAL METHODS OF TEST FOR PIGMENTS
PART III
DETERMINATION OF MATTER SOLUBLE IN WATER
(HOT EXTRACTION METHOD)
INTRODUCTION
This document is a part of ISO/R 787, General methods of test for pigments.
1. SCOPE
1.1 Part III of this IS0 Recommendation describes a general method of test for Ldtermining LLe
percentage by mass of matter soluble in boiling water, in a sample of pigment.
1.2 Part VI11 of this IS0 Recommendation* describes a method for determining the percentage of
matter soluble in cold water. For most pigments, these two test methods will give different
results, and it is therefore essential to state clearly in a specification, which method is to be
used, and in a test report, which method has been used.
NOTE. - When this general method is applicable to a given pigment, only a cross-reference to it need be
included in the IS0 Recommendation relating to that pigment, with a note of any detailed modification
of the special properties of the pigment in question. Only when neither of
which may be needed in view
these general methods is applicable to a particular pigment should a special method for determination of
water-soluble matter be specified.
2. APPARATUS
2.1 One-mark volumenic flask, of 250 ml.
2.2 Filter paper, fine-textured, or diaphragm, or colloid filter,
2.3 Evaporation dish, flat bottomed, of glass, platinum, glazed porcelain or silica.
2.4 Oven, capable of being maintained at a temperature of 105 f 2 OC.
2.5 Balance, sensitivity 1 mg.
2.6 Desiccator.
3. SAMPLING
The sample of pigment used for the test should be taken in accordance with the provisions of IS0
Recommendation R 842, Sampling raw materials for paints and varnishes.
*
At present, Draft IS0 Recommendation No. 125 1.
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ISO/R 787/III-1%8 (E)
4. PROCEDURE
4.1 Test portion
Weigh 2 to 20 g of the sample, to the nearest 0.01 g, into a beaker.
NOTE. - The mass of pigment used should be chosen according to the amount of water-soluble matter in the
pigment. This is particularly important for pigments that contain large amounts of matter soluble in water.
4.2 Determination
Wet the pigment in the beaker with a few millilitres of water or other suitable liquid.
NOTE. - If the pigment does not disperse easily in water, a wetting agent may be used; in the cas of pig-
ments not soluble in ethanol, 5 ml of ethanol may be used; in the case of pigments soluble in ethanol, a non-
ionic wetting agent such as, for example, 10 ml of a 0.01 oL solution of a polyethylene oxide condensate
should be used. If the wetting agent is non-volatile under the conditions of test an appropriate correction
should be made to the fmal water-soluble matter figure.
Add 200 ml of freshly distilled water, stir, and boil for 5 minutes unless another period is
specified. A coagulating agent can be used if the semi-colloidal nature of the pigment makes
this desirable, provided the agent selected is not such as to affect the subsequent determination
of the acidity or alkalinity of the aqueous extract,* and provided only the minimum quantity is
use d.
Cool rapidly to room temperature, transfer to the volumetric flask (2.1) and dilute to the mark
with neutral distilled water. Mix thoroughly by shaking and inversion, and filter through the
filter paper (2.2) or, in the case of pigments which are difficult to fil
...