ASTM D1844-86(2020)

Standard Test Methods for Chemical Analysis of Basic Lead Silicochromate

SIGNIFICANCE AND USE
3.1 These test methods may be used to confirm the stated lead oxide, chromium trioxide and silica content of basic lead silicochromate and is useful for quality control.
SCOPE
1.1 These test methods cover the chemical analysis of the pigment commercially known as basic lead silicochromate and are applicable to pigment supplied by the manufacturer and to pigment, but not mixed pigments, separated from liquid coatings. The presence of basic lead silicochromate species shall be confirmed by X-ray diffraction analysis (see Specification D1648).  
1.2 For liquid coatings the pigment must first be separated from the vehicle before conducting the analysis.  
1.3 The analytical procedures appear in the following order:    
Sections    
Lead oxide  
6 to 14  
Chromium trioxide  
15 to 23  
Silica  
24 to 27  
Moisture and other volatile matter  
28  
Coarse particles  
29  
Oil absorption  
30  
Mass color and tinting strength  
31  
1.4 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.  
1.5 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 use.  
1.6 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

• Status: Published
• Publication Date: 31-May-2020
• ICS: 87.060.10 - Pigments and extenders
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.31 - Pigment Specifications

Relations

• Replaces: ASTM D1844-86(2014) - Standard Test Methods for Chemical Analysis of Basic Lead Silicochromate
• Effective Date: 01-Jun-2020
• Refers: ASTM D1648-86(2020) - Standard Specification for Basic Lead Silicochromate Pigment
• Effective Date: 01-Jun-2020
• Refers: ASTM D2371-19 - Standard Test Method for Pigment Content of Solvent-Reducible Paints
• Effective Date: 15-Dec-2019
• Refers: ASTM D1648-86(2014) - Standard Specification for Basic Lead Silicochromate Pigment
• Effective Date: 01-Dec-2014
• Refers: ASTM D280-01(2012) - Standard Test Methods for Hygroscopic Moisture (and Other Matter Volatile Under the Test Conditions) in Pigments
• Effective Date: 01-Nov-2012
• Refers: ASTM D281-12 - Standard Test Method for Oil Absorption of Pigments by Spatula Rub-out
• Effective Date: 15-Apr-2012
• Refers: ASTM D2371-85(2010) - Standard Test Method for Pigment Content of Solvent-Reducible Paints (Withdrawn 2019)
• Effective Date: 01-Dec-2010
• Refers: ASTM D1648-86(2008) - Standard Specification for Basic Lead Silicochromate Pigment
• Effective Date: 01-Jul-2008
• Refers: ASTM D387-00(2008) - Standard Test Method for Color and Strength of Chromatic Pigments with a Mechanical Muller
• Effective Date: 01-Feb-2008
• Refers: ASTM D185-07 - Standard Test Methods for Coarse Particles in Pigments
• Effective Date: 01-Jul-2007
• Refers: ASTM D281-95(2007) - Standard Test Method for Oil Absorption of Pigments by Spatula Rub-out
• Effective Date: 01-Jul-2007
• Refers: ASTM D280-01(2007) - Standard Test Methods for Hygroscopic Moisture (and Other Matter Volatile Under the Test Conditions) in Pigments
• Effective Date: 01-Feb-2007
• Refers: ASTM D1193-06 - Standard Specification for Reagent Water
• Effective Date: 01-Mar-2006
• Refers: ASTM D2371-85(2005) - Standard Test Method for Pigment Content of Solvent-Reducible Paints
• Effective Date: 01-Jan-2005
• Refers: ASTM D1648-86(2003) - Standard Specification for Basic Lead Silicochromate Pigment
• Effective Date: 01-Dec-2003

Overview

ASTM D1844-86(2020): Standard Test Methods for Chemical Analysis of Basic Lead Silicochromate provides established procedures for determining the chemical composition of basic lead silicochromate pigments. Developed by ASTM International, this standard is essential for manufacturers, laboratories, and quality assurance professionals working with basic lead silicochromate pigments used in paint and coatings applications. Its methods confirm the presence and specific content of lead oxide, chromium trioxide, and silica, supporting consistent product quality and regulatory compliance.

The standard applies to both pigment supplied by manufacturers and pigment separated from liquid coatings (but not from pigment mixtures). Before analysis, the pigment from liquid coatings must be isolated, and the identity of the pigment is confirmed via X-ray diffraction per ASTM D1648.

Key Topics

• Chemical Composition Analysis: Methods to determine lead oxide, chromium trioxide, and silica percentages in basic lead silicochromate pigments.
• Sample Preparation: Procedures for preparing pigment samples, including separation from coatings and grinding to a fine powder for accurate testing.
• Quality Assurance: Useful for confirming that a pigment meets the composition specifications required for its intended performance in coatings.
• Test Procedures Include:
  • Lead oxide (PbO) determination: gravimetric and titrimetric methods.
  • Chromium trioxide (CrO₃) analysis with safeguards against interferences.
  • Silica (SiO₂) quantification.
  • Moisture and other volatile matter measurement.
  • Assessment of coarse particles, oil absorption, mass color, and tinting strength.
• Precision and Reliability: Guidelines on repeatability for analytical results within laboratories, ensuring consistent and reliable outcomes.
• Safety and Compliance: Users are responsible for implementing appropriate health, safety, and environmental controls when using reagents and conducting these analyses.

Applications

ASTM D1844-86(2020) is critical for:

• Pigment Manufacturers: To certify product specifications and support customer quality requirements for basic lead silicochromate.
• Paint and Coatings Industry: To verify pigment content and properties in coatings formulations, ensuring color consistency and performance standards.
• Quality Control Laboratories: To conduct routine chemical analyses of pigment samples-either as supplied or extracted from coatings-to ensure conformity with manufacturing and industry standards.
• Regulatory Compliance: To provide documented proof of compliance with safety and environmental regulations regarding pigment composition, especially where specific limits for lead, chromium, or silica are set by authorities.

Proper use of these standardized test methods ensures batch-to-batch consistency and enables traceability when investigating quality or performance issues in finished coatings. Additionally, the standard’s alignment with international trade practices facilitates global acceptance and reduces technical barriers.

Related Standards

• ASTM D1648 - Specification for Basic Lead Silicochromate Pigment (includes identity confirmation by X-ray diffraction).
• ASTM D185 - Test Methods for Coarse Particles in Pigments.
• ASTM D2371 - Test Method for Pigment Content of Solvent-Reducible Paints (for pigment separation).
• ASTM D280 - Test Methods for Hygroscopic Moisture and Other Volatile Matter in Pigments.
• ASTM D281 - Test Method for Oil Absorption of Pigments.
• ASTM D387 - Test Method for Color and Strength of Chromatic Pigments.
• ASTM D1193 - Specification for Reagent Water.

For organizations analyzing pigments, referencing these related ASTM standards ensures comprehensive and harmonized laboratory practices throughout testing and quality control processes.

Keywords: basic lead silicochromate, pigment analysis, ASTM D1844, lead oxide, chromium trioxide, silica content, coatings quality control, pigment testing standard.

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: D1844 − 86 (Reapproved 2020)
Standard Test Methods for
Chemical Analysis of Basic Lead Silicochromate
This standard is issued under the fixed designation D1844; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 These test methods cover the chemical analysis of the 2.1 ASTM Standards:
D185Test Methods for Coarse Particles in Pigments
pigment commercially known as basic lead silicochromate and
are applicable to pigment supplied by the manufacturer and to D280Test Methods for Hygroscopic Moisture (and Other
Matter Volatile Under the Test Conditions) in Pigments
pigment, but not mixed pigments, separated from liquid
D281Test Method for Oil Absorption of Pigments by
coatings. The presence of basic lead silicochromate species
Spatula Rub-out
shall be confirmed by X-ray diffraction analysis (see Specifi-
D387Test Method for Color and Strength of Chromatic
cation D1648).
Pigments with a Mechanical Muller
1.2 For liquid coatings the pigment must first be separated
D1193Specification for Reagent Water
from the vehicle before conducting the analysis.
D1648SpecificationforBasicLeadSilicochromatePigment
1.3 Theanalyticalproceduresappearinthefollowingorder:
D2371 Test Method for Pigment Content of Solvent-
Sections
Reducible Paints
Lead oxide 6 to 14
Chromium trioxide 15 to 23
3. Significance and Use
Silica 24 to 27
3.1 These test methods may be used to confirm the stated
Moisture and other volatile matter 28
Coarse particles 29
lead oxide, chromium trioxide and silica content of basic lead
Oil absorption 30
silicochromate and is useful for quality control.
Mass color and tinting strength 31
4. Purity of Reagents
1.4 The values stated in SI units are to be regarded as the
standard. The values given in parentheses are for information
4.1 Reagent grade chemicals shall be used in all tests.
only.
Unlessotherwiseindicated,itisintendedthatallreagentsshall
1.5 This standard does not purport to address all of the conform to the specifications of the Committee on Analytical
Reagents of the American Chemical Society, where such
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- specifications are available. Other grades may be used, pro-
vided it is first ascertained that the reagent is of sufficiently
priate safety, health, and environmental practices and deter-
mine the applicability of regulatory limitations prior to use. high purity to permit its use without lessening the accuracy of
the determination.
1.6 This international standard was developed in accor-
dance with internationally recognized principles on standard-
4.2 Unless otherwise indicated, references to water shall be
ization established in the Decision on Principles for the
understood to mean reagent water conforming to Type II of
Development of International Standards, Guides and Recom-
Specification D1193.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
These test methods are under the jurisdiction of ASTM Committee D01 on ACS Reagent Chemicals, Specifications and Procedures for Reagents and
Paint and Related Coatings, Materials, and Applications and are the direct
Standard-Grade Reference Materials, American Chemical Society, Washington,
responsibility of Subcommittee D01.31 on Pigment Specifications.
DC. For suggestions on the testing of reagents not listed by theAmerican Chemical
Current edition approved June 1, 2020. Published June 2020. Originally
Society, see Analar Standards for Laboratory Chemicals, BDH Ltd., Poole, Dorset,
approved in 1961. Last previous edition approved in 2014 as D1844–86(2014). U.K., and the United States Pharmacopeia and National Formulary, U.S. Pharma-
DOI: 10.1520/D1844-86R20. copeial Convention, Inc. (USPC), Rockville, MD.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D1844 − 86 (2020)
5. Preparation of Sample (1+1). Destroy the organic material by evaporating the
solution to dense white fumes, making further additions of
5.1 Thoroughly mix liquid coatings and separate in accor-
HNO until there is no charring.
dancewithTestMethodD2371sufficientpigmenttoenablethe
required analyses to be carried out.
8.3 Cool the solution, add 10 mLof water, and evaporate to
fumes. Repeat the addition of water and the evaporation. Cool
5.2 Thoroughly mix pigment supplied as such and grind
the solution, add 40 mL of water, and bring the solution to
separated pigment to a fine powder in a mortar and pestle
boiling. Cool the solution and add 50 mLof isopropyl alcohol
before taking portions for analysis.
(98%), stir, and allow the solution to stand cold for at least 4
TOTAL LEAD AS LEAD OXIDE-GRAVIMETRIC
h. Filter, using paper pulp, and wash once with cold isopropyl
METHOD
alcohol (50%) containing 10 mL of H SO (sp gr 1.84)/100
2 4
mL.
6. Apparatus
8.4 Transfer the precipitate to the original beaker with 150
6.1 Glass Filtering Crucible(medium-porosityfritteddisk),
mLofwater,add50mLoftheammoniumacetatesolution,and
dried to constant weight before use.
boilthesolutionuntiltheleadsulfatedissolves.Filterwhilehot
6.2 Platinum Dish.
through the original paper and wash well (6 to 8 washes) with
hot water. To the filtrate add 5 mL of glacial acetic acid, heat
7. Reagents
the solution to boiling, and add 20 mL of saturated K Cr O
2 2 7
7.1 Acetic Acid (Glacial). solution. Boil the solution until the precipitate turns orange,
and allow to stand on a warm plate for at least 2 h. Filter
7.2 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
through a glass filtering crucible (medium-porosity fritted
monium hydroxide (NH OH).
disk), wash three times with hot water, and finally once with
7.3 AmmoniumAcetate,Acid Solution—To300mLofwater
alcohol. Dry in an oven at 105°C for 2 h, cool, and weigh.
add an equal volume of NH OH. Neutralize with glacial acetic
acid and add 20 mL in excess.
9. Calculation
7.4 Hydrochloric Acid (sp gr 1.19)—Concentrated hydro-
9.1 Calculatethepercentoftotalleadasleadoxide(PbO)as
chloric acid (HCl).
follows:
7.5 Hydrofluoric Acid (47 %)—Concentrated hydrofluoric
PbO, % 5 P 369.06 /S
~ !
acid (HF).
where:
7.6 Hydrogen Sulfide (H S)—Handle and use H S in hood.
2 2
P = lead chromate (PbCrO ) precipitate, g,
7.7 Isopropyl Alcohol (50 and 98%).
S = sample used, g, and
7.8 Nitric Acid (sp gr 1.42)—Concentrated nitric acid
molecularweight ~PbO!
(HNO ).
molecularweight ~PbCrO !
7.9 Potassium Dichromate Solution (saturated)—Prepare a
223.21
5 0.6906 3100 forpercent 5 69.06
~ !
saturatedsolutionofpotassiumdichromate(K Cr O )inwater.
323.21
2 2 7
7.10 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
69.06 represents the gravimetric factor to convert grams of
concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
PbCrO to grams of PbO.
of water.
This gravimetric factor has led to high results due to the
presence of mixed lead chromates and an empirical factor can
8. Procedure
be used to compensate:
8.1 Weigh accurately (to 0.1 mg)1gofthe sample into a
Empiricalfactor 5 69.06 30.9944 5 68.67
platinum dish. Add 5 mL of HNO and 10 mL of HF.
Cautiously evaporate to dryness on a steam bath. Repeat the
ALTERNATIVE METHOD FOR TOTAL LEAD AS
addition of HNO and HF and again cautiously evaporate to
LEADOXIDE—TITRIMETRIC METHOD
dryness. Wash the sides of the dish with a little water and
evaporate to dryness. Wet the residue with 5 mL of HNO ,
3 10. Apparatus
warmgently,andtransfertheresiduetoa400-mLbeakerusing
10.1 Platinum Dish.
a policeman. Neutralize with NH OH, and then make the
solution just acid with HCl, adding 5 mL in excess. Dilute to
10.2 Filter Paper, ashless, medium texture, or paper pulp.
200 mL and heat to just below the boiling point until solution
is complete.
11. Reagents
8.2 Pass H S through the solution for about 20 min. Filter,
11.1 Ammonium Hydroxide (sp gr 0.90)—Concentrated am-
using paper pulp. Wash the precipitate five to six times with
monium hydroxide (NH OH).
water just acid with HCl and saturated with H S. Transfer the
paper and precipitate to the original beaker, add 25 mL of 11.2 Glacial Acetic Acid (min 99.7 %)—Concentrated gla-
HNO ,boiluntiltheresidueiswhite,thenadd10mLofH SO cial acetic acid (CH COOH).
3 2 4 3
D1844 − 86 (2020)
11.3 Acid Ammonium Acetate Buffer—Mix 400 mL of dis- 11.15 Sulfuric Acid (1 + 1)—Carefully mix 1 volume of
tilled water and 400 mLof ammonium hydroxide (sp gr 0.90). concentrated sulfuric acid (H SO , sp gr 1.84) with 1 volume
2 4
Add 375 mL of reagent grade glacial acetic acid slowly while of water.
stirring.
12. Procedure
11.4 Cupric Sulfate Solution (0.1 M)—Dissolve 25 g of
12.1 Dissolve1gof pigment in accordance with 8.1 and
CuSO ·5H O in distilled water and dilute to 1 L.
4 2
8.2.
11.5 Disodium Ethylenediaminetetracetate Dihydrate (0.05
12.2 Cool, so that the addition of 25 mL of water does not
M) (EDTA solution) —Dissolve 18.6 g of the salt in distilled
cause excessive splattering of the sulfuric acid; the solution at
water and dilute to 1 L. Standardize the solution as follows:
this point should be water white. Add ammonium hydroxide
Transfer 25 mL of lead standard (11.14) to a 400-mL beaker.
(spgr0.90)untilthepHofthesolutionis5to5.5(asindicated
Add concentrated ammonium hydroxide (11.1) dropwise until
by pH paper). Add 50 mL of acid ammonium acetate (11.3),
a permanent precipitate just forms. Add 25 mL of acid
boil 5 min, dilute to 200 mLwith water, heat to boiling, add 4
ammonium acetate (11.3), dilute to 200 mL, heat to boiling,
dropsofcopper-EDTA(11.7)and12dropsofPAN(11.13)and
add 4 drops of copper EDTA (11.7) and 12 drops of PAN
titrate while hot with standard EDTA to a clear yellow.
(11.13) and titrate with the EDTA to a clear yellow.
13. Calculation
1mLNa EDTA 5 0.2790/V g PbO
13.1 Calculate the percent lead oxide as follows:
where:
V 3L 3100
V = EDTA required for titration, mL
PbO, % 5
S
g = lead oxide, g, and
0.05 M×0.22321=0.01116gPbOin1mLofleadstandard where:
(11.14).
V = EDTA required for titration, mL,
25 mL × 0.05 M × 0.22321g/mmol =0.2790 g PbO in 25
L = lead equivalent of EDTA solution, and
mL of lead standard (11.14). S = specimen weight, g.
11.6 Murexide Indicator Tablets—Ammonium salt of pur-
14. Precision and Bias
puric acid.
14.1 On the basis of an interlaboratory study of the method
11.7 Copper-EDTA Solution—Mix equivalent amounts of
in which operators in three laboratories analyzed two paints
cupric sulfate solution (11.4) and EDTA solution (11.5) and
containing basic lead silicochromate with iron oxide the
store in a dropping bottle. The cupric sulfate EDTA equiva-
following criteria should be used for judging the acceptability
lence may be determined as follows: Pipet 10 mL of cupric
of the results at the 95% confidence level:
sulfate into a beaker, add concentrated ammonium hydroxide
14.1.1 Repeatability—Two results, each the mean of dup
...