ASTM D50-90(2023)
(Test Method)Standard Test Methods for Chemical Analysis of Yellow, Orange, Red, and Brown Pigments Containing Iron and Manganese
Standard Test Methods for Chemical Analysis of Yellow, Orange, Red, and Brown Pigments Containing Iron and Manganese
SIGNIFICANCE AND USE
3.1 These test methods compile in one place, recommended procedures for analyzing inorganic colored pigments. These pigments are used extensively in paints, and for this reason their compositions are important to the formulators and user.
SCOPE
1.1 These test methods cover procedures for the chemical analysis of yellow, orange, red, and brown pigments containing iron and manganese. The test methods apply specifically to the following pigments: synthetic hydrated yellow iron oxide, yellow ocher, red and brown iron oxides, raw and burnt umber, raw and burnt sienna, and venetian red.
1.2 The analytical procedures appear in the following order:
ASTM
Method
Refer-
Dry Pigments
Sections
ences
Moisture and Other Volatile Matter
6
D280
Loss on Ignition
7
Coarse Particles
8
D185
Matter Soluble in Water
9
D1208
Organic Coloring Matter
10
Iron Oxide
11 and 12
Calcium Compounds (Reported as CaO)
13 and 14
Sulfates Soluble in Hydrochloric Acid
15 and 16
Lead Chromate (in Ochers)
17
Calcium Carbonate (in Venetian Red)
18
C25
Manganese (in Siennas and Umbers)
19 and 20
Pigment Pastes in Oil
Pigment Content
21
D1208
Moisture and Other Volatile Matter
22
D1208
Nonvolatile Matter in Vehicle
23
Moisture by Distillation
24
D1208
Coarse Particles and Skins
25
D185
Consistency (Stormer)
26
D562
1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to us.
1.5 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
General Information
Relations
Standards Content (Sample)
This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D50 − 90 (Reapproved 2023)
Standard Test Methods for
Chemical Analysis of Yellow, Orange, Red, and Brown
Pigments Containing Iron and Manganese
This standard is issued under the fixed designation D50; the number immediately following the designation indicates the year of original
adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A superscript
epsilon (´) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use.
1.1 These test methods cover procedures for the chemical
1.5 This international standard was developed in accor-
analysis of yellow, orange, red, and brown pigments containing
dance with internationally recognized principles on standard-
iron and manganese. The test methods apply specifically to the
ization established in the Decision on Principles for the
following pigments: synthetic hydrated yellow iron oxide,
Development of International Standards, Guides and Recom-
yellow ocher, red and brown iron oxides, raw and burnt umber,
mendations issued by the World Trade Organization Technical
raw and burnt sienna, and venetian red.
Barriers to Trade (TBT) Committee.
1.2 The analytical procedures appear in the following order:
2. Referenced Documents
ASTM
Method
2.1 ASTM Standards:
Refer-
Dry Pigments Sections ences C25 Test Methods for Chemical Analysis of Limestone,
Quicklime, and Hydrated Lime
Moisture and Other Volatile Matter 6 D280
D185 Test Methods for Coarse Particles in Pigments
Loss on Ignition 7
Coarse Particles 8 D185
D280 Test Methods for Hygroscopic Moisture (and Other
Matter Soluble in Water 9 D1208
Matter Volatile Under the Test Conditions) in Pigments
Organic Coloring Matter 10
D562 Test Method for Consistency of Paints Measuring
Iron Oxide 11 and 12
Calcium Compounds (Reported as CaO) 13 and 14
Krebs Unit (KU) Viscosity Using a Stormer-Type Viscom-
Sulfates Soluble in Hydrochloric Acid 15 and 16
eter
Lead Chromate (in Ochers) 17
D1193 Specification for Reagent Water
Calcium Carbonate (in Venetian Red) 18 C25
Manganese (in Siennas and Umbers) 19 and 20 D1208 Test Methods for Common Properties of Certain
Pigments
Pigment Pastes in Oil
E11 Specification for Woven Wire Test Sieve Cloth and Test
Pigment Content 21 D1208
Sieves
Moisture and Other Volatile Matter 22 D1208
Nonvolatile Matter in Vehicle 23
3. Significance and Use
Moisture by Distillation 24 D1208
Coarse Particles and Skins 25 D185
3.1 These test methods compile in one place, recommended
Consistency (Stormer) 26 D562
procedures for analyzing inorganic colored pigments. These
1.3 The values stated in SI units are to be regarded as
pigments are used extensively in paints, and for this reason
standard. No other units of measurement are included in this
their compositions are important to the formulators and user.
standard.
4. Preparation of Sample
1.4 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the
4.1 Mix the sample thoroughly and take a representative
responsibility of the user of this standard to establish appro-
portion for analysis. Reduce any lumps or coarse particles to a
fine powder by grinding. Grind extracted pigments to pass a
No. 80 (180 μm) sieve (see Specification E11 for detailed
These test methods are under the jurisdiction of ASTM Committee D01 on
Paint and Related Coatings, Materials, and Applications and are the direct
responsibility of Subcommittee D01.31 on Pigment Specifications. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved June 1, 2023. Published June 2023. Originally contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
approved in 1917. Last previous edition approved in 2019 as D50 – 90 (2019). DOI: Standards volume information, refer to the standard’s Document Summary page on
10.1520/D0050-90R23. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D50 − 90 (2023)
requirements). Discard any skins that do not pass through the of ethyl alcohol (95 %) and decant as before. Boil the residue
sieve. Mix the finely ground pigment thoroughly. with 25 mL of 1 N alcoholic sodium hydroxide (NaOH)
solution and again decant. Boil another 2 g portion of the
5. Purity of Reagents
sample with 25 mL of chloroform, let settle, and decant the
5.1 Purity of Reagents—Unless otherwise indicated, it is supernatant liquid. If any one of the above solutions is colored,
intended that all reagents shall conform to the specifications of
organic coloring matter is indicated (Note 2). If the solutions
the Committee on Analytical Reagents of the American Chemi- remain colorless, organic colors are probably absent, but may
cal Society, where such specifications are available. Other
be tested for by reference to procedures given in standard
grades may be used, provided it is first ascertained that the reference works, taking into account the nature of the pigment
reagent is of sufficiently high purity to permit its use without
involved.
lessening the accuracy of the determination.
NOTE 2—With this class of pigments indication of presence of an
5.2 Purity of Water—Unless otherwise indicated, references organic color may often be noted by the characteristic odor given off on
ignition.
to water shall be understood to mean Type II reagent water
conforming to Specification D1193.
Iron Oxide
DRY PIGMENTS
11. Reagents
Moisture and Other Volatile Matter
11.1 Stannous Chloride Solution (SnCl ·2H O)—Dissolve
2 2
6. Procedure
50 g of SnCl ·2H O in 300 mL of hydrochloric acid (HCl) (sp
2 2
gr 1.19) and dilute with water to 500 mL. Keep the clear
6.1 Determine moisture and other volatile matter in accor-
solution in a tightly stoppered bottle containing some metallic
dance with Method A of Test Methods D280.
tin.
Loss on Ignition
11.2 Mercuric Chloride Solution (HgCl )—Prepare a satu-
rated solution of HgCl (60 g ⁄L to 100 g ⁄L).
7. Procedure
7.1 Weigh accurately approximately 1 g of pigment into a 11.3 Sulfuric-Phosphoric Acid Mixture—Mix 150 mL of
sulfuric acid (H SO ) (sp gr 1.84) with 150 mL of phosphoric
previously weighed and ignited porcelain crucible (Note 1).
2 4
Cover and ignite to constant weight over a bunsen or Meker acid (H PO ) (85 %) and dilute with water to 1 L.
3 4
burner or in an electric furnace at a temperature of approxi-
11.4 Diphenylamine Indicator—Dissolve 1 g of diphe-
mately 900 °C. Cool in a desiccator, weigh, and calculate the
nylamine in 100 mL of H SO (sp gr 1.84).
2 4
percent loss on ignition. This figure may include combined
11.5 Standard Potassium Dichromate Solution (K Cr O )
2 2 7
water, carbon dioxide (CO ), organic matter, and some sulfuric
(0.1 N)—Dissolve 4.904 g of K Cr O in water and dilute to
2 2 7
oxide (SO ) if much calcium sulfate (CaSO ) is present. The
3 4
1 L. Standardize against the National Institute of Standards and
CO may be determined on a separate portion if desired.
Technology standard sample No. 27 of Sibley iron ore.
NOTE 1—It is inadvisable to use platinum unless it is known that
11.6 Potassium Ferricyanide Solution (K Fe(CN) )—
3 6
attacking substances are absent.
Optional. Dissolve approximately 0.01 g of K Fe(CN) in
3 6
Coarse Particles
50 mL of water. This solution must be made fresh when wanted
because it does not keep.
8. Procedure
8.1 Determine coarse particles in accordance with Test
12. Procedure
Methods D185.
12.1 According to the amount of iron in the pigment, weigh
0.3 g to 1.0 g of the pigment and ignite in a porcelain crucible
Matter Soluble in Water
at a dull red heat to destroy organic matter. Transfer to a
9. Procedure
400 mL beaker and add 25 mL of HCl (sp gr 1.19). Cover with
a watchglass and digest just short of boiling (80 °C to 90 °C)
9.1 Determine matter soluble in water in accordance with
until no dark specks can be seen in the insoluble residue. The
Test Methods D1208.
addition of a few drops of SnCl solution after adding the acid
Organic Coloring Matter greatly assists dissolving of the iron. When the residue is light
in color, the solution of iron may be considered complete. This
10. Procedure
may take from 15 min to 1 h, or longer.
10.1 Boil 2 g of the sample with 25 mL of water, let settle,
12.2 Add 25 mL to 50 mL of water and heat to gentle
and decant the supernatant liquid. Boil the residue with 25 mL
boiling (avoid vigorous prolonged boiling). Slowly add SnCl
solution dropwise until the last drop makes the solution
Reagent Chemicals, American Chemical Society Specifications, American
colorless or free from any tinge of yellow, then add 1 or 2 drops
Chemical Society, Washington, DC. For suggestions on the testing of reagents not
listed by the American Chemical Society, see Analar Standards for Laboratory
Chemicals, BDH Ltd., Poole, Dorset, U.K., and the United States Pharmacopeia
and National Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, Reference may be made to the following: Payne, H. F., “Organic Coatings
MD. Technology,” Vol II, John Wiley & Sons, Inc., New York, N. Y., 1961.
D50 − 90 (2023)
in excess. It is best to keep the watchglass on the beaker while the beaker to stand on a small hot plate during the titration.)
adding the SnCl solution, with agitation of the hot iron The use of a small thermometer (nonmercury type) as a stirring
solution after each addition. If too much SnCl is added by rod is most convenient. Keep the KMnO solution in a
2 4
mistake, add potassium permanganate (KMnO ) to the solution glass-stoppered bottle painted black to keep out light, or in a
until a yellow color appears, then again add SnCl dropwise brown glass bottle stored in a dark place.
until the yellow color just disappears, again adding one or two
13.4 Calculate the calcium oxide (CaO) value of the solu-
drops in excess. Dilute with 200 mL of cold water; then add all
tion as follows:
at once with vigorous stirring 15 mL of HgCl solution. Let
C 5 W × V × 0.4185 (2)
~ !
1 1
stand 3 min to 4 min. A slight white precipitate should form. If
none, or a heavy grayish precipitate forms, the determination
where:
should be discarded and repeated.
C = CaO equivalent of the KMnO solution, g/mL,
W = sodium oxalate used, g, and
12.3 Add 15 mL of H SO -H PO mixture and 3 drops of
2 4 3 4
V = KMnO solution required for the titration, mL.
diphenylamine indicator solution. Titrate with K Cr O
1 4
2 2 7
solution, taking the sudden change of the dark green color to a
0.4185 5 CaO/Na C O 5 56.08/134.01 (3)
2 2 4
blue-black color as the end point.
14. Procedure
12.4 If preferred, K Fe(CN) may be used as an external
3 6
indicator. In this case omit the addition of the H SO -H PO 14.1 Weigh 2.5 g of sample, transfer to a porcelain crucible,
2 4 3 4
mixture and the diphenylamine indicator. Titrate with the and ignite at a dull red heat to destroy organic matter. Cool,
K Cr O solution as in 12.3, except toward the end take out a transfer to a 600 mL beaker, and add 100 mL of HCl (1 + 1).
2 2 7
very small drop of the solution being titrated and touch this to Digest just short of boiling until no dark specks can be seen in
a drop of the K Fe(CN) solution, best placed on a paraffined the insoluble residue. Add ammonium hydroxide (NH OH) (sp
3 6
surface. Toward the end point the blue is replaced by a gr 0.90) in slight excess and about 2 mL of H O (30 %). Cool,
2 2
bluish-green coloration, perceptible at the junction of the two transfer to a 500 mL graduated flask, and dilute to 500 mL. Mix
solutions. Take as the end point when no trace of the bluish- thoroughly and filter through a dry paper.
green coloration can be detected.
14.2 Take 100 mL of the filtrate (corresponding to 0.5 g of
sample), add a few drops of NH OH, heat to boiling, and add
12.5 Calculation—Calculate the percent of iron oxide
(Fe O ), A, as follows: an excess of saturated ammonium oxalate solution. Continue
2 3
the boiling until the precipitate becomes granular. Let stand
A 5 ~FV/S! × 100 (1)
about 30 min, filter, and wash three times with 20 mL aliquots
where:
of hot water until free of ammonium oxalate.
F = Fe O equivalent of the K Cr O solution, g/mL,
2 3 2 2 7
14.3 Place the beaker in which precipitation was made
V = K Cr O solution required, mL, and
2 2 7
under the funnel, pierce the apex of the filter with a stirring rod,
S = sample used, g.
and wash the precipitate into the beaker with hot water. Pour
warm H SO (1 + 4) through the paper and wash a few times.
Calcium Compounds (Reported as CaO) 2 4
Add about 30 mL of H SO (1 + 4) and dilute to about 250 mL.
2 4
Heat to 90 °C and titrate at once with KMnO solution. (The
13. Reagents
temperature of the solution should not be below 60 °C when
13.1 Ammonium Oxalate Saturated Solution—Heat to boil-
the end point is reached.)
ing 5 g powdered ammonium oxalate [(NH ) C O ·H O] and
4 2 2 4 2
14.4 Calculation—Calculate the percent of calcium
100 mL of water. Allow to cool.
compounds, A, in terms of CaO, as follows:
13.2 Hydrogen Peroxide (H O ) (30 %).
2 2
A 5 V C/0.5 × 100 (4)
~ !
13.3 Potassium Permanganate, Standard Solution—
where:
(KMnO ) (0.1 N)—Dissolve 3.16 g of KMnO in water and
4 4
V = KMnO solution required by the specimen, mL, and
dilute to 1 L. Let stand 8 days to 14 days, siphon off the clear
2 4
C = CaO equivalent of the KMnO solution, g/mL.
solution (or filter through a medium-porosity fritted disk), and
standardize against the National Institute of Standards and
Sulfates Soluble in Hydrochloric Acid
Technology (NIST) standard sample No. 40 of sodium oxalate
(Na C O ) as follows: In a 400 mL beaker dissolve 0.2500 g to
2 2 4
15. Reagent
0.3000 g of the NIST Na C O in 250 mL of hot water (80 °C
2 2 4
15.1 Barium Chloride Solution—Dissolve 117 g of barium
to 90 °C) and add 15 mL of H SO (1 + 1). Titrate at once with
2 4
chloride (BaCl ·2H O) in water and dilute to 1 L.
KMnO solution, stirring the liquid vigorously and continu- 2 2
ously. The KMnO must not be added more rapidly than
16. Procedure
10 mL ⁄min to 15 mL ⁄min, and the last 0.5 mL to 1 mL must be
added dropwise with particular care to allow each drop to be 16.1 Weigh 1 g of the sample and add 30 mL of HCl (sp gr
fully decolorized before the next is introduced. The solution 1.19). Boil 10 min, add about
...
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