ASTM D8090-24

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
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Designation: D8090 − 17 D8090 − 24
Standard Test Method for
Particle Size Distribution and Shape Analysis of Paints and
Pigments Using Dynamic Imaging Methods
This standard is issued under the fixed designation D8090; 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.
1. Scope
1.1 This test method covers the determination of particle size distribution and particle shape of liquid paints and pigmented liquid
coatings by Dynamic Image Analysis. This method includes the reporting of particles ≥1 μm in size and up to 300 μm in size.
NOTE 1—Shape is used to classify particles, droplets and bubbles and is not a reporting requirement.
NOTE 2—The term paint(s) as used in this document includes liquid paint and liquid pigmented coatings.
1.1.1 Some paints may be too viscous to flow through the imaging instrument without dilution which may be used to help the paint
flow as long as significant contamination is not introduced into the paint.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 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 and healthsafety, health, and environmental practices and determine
the applicability of regulatory limitations prior to use.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
D16 Terminology for Paint, Related Coatings, Materials, and Applications
D3925 Practice for Sampling Liquid Paints and Related Pigmented Coatings
2.2 Other Documents:
NIST SRM 1982 Thermal Spray Powder – Particle Size Distribution
ISO12103-1 Medium Test Dust
3. Terminology
3.1 For the definition of terms used in this standard refer to Terminology D16.
This test method is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.24 on Physical Properties of Liquid Paints and& Paint Materials.
Current edition approved June 1, 2017Feb. 1, 2024. Published July 2017February 2024. DOI: 10.1520/D8090-17.Originally approved in 2017. Last previous edition
approved in 2017 as F3261 – 17. DOI: 10.1520/D8090-24.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D8090 − 24
3.2 Definitions:
3.2.1 bubble, n—a non paint, gaseous formation within the paint, generally spherical in shape and visible as a thick walled ring
with a transparent center.
3.2.2 droplet, n—a non paint, liquid formation within the paint, generally spherical in shape and visible as a thin walled ring with
a transparent center.
3.2.3 projected equivalent particle diameter, n—the diameter calculated from the projected area o fa of a particle if that area
formed a circle, and in equation form isis:
Projected Equivalent Particle Diameter ~D! 5 SQRT~Area/ ~π ⁄ 4!!5=~Area/0.785!
3.2.4 projected equivalent particle volume (V ), n—the particle volume based on the projected equivalent particle diameter, and
D
in equation form is
Projected Equivalent Particle Volume V 5 πD ⁄6 (1)
~ !
D
3.2.4 volumecount fraction, n—the fraction of the total volumecount of particles measured which are below a given
percent,percent value, and are denoted as follows:
3.2.4.1 Dv10—Dn10—the projected equivalent diameter below which 10 % of the total volumecount of all particles analyzed
is represented.
3.2.4.2 Dv50—Dn50—the projected equivalent diameter below which 50 % of the total volumecount of all particles analyzed
is represented.
3.2.4.3 Dv90—Dn90—the projected equivalent diameter below which 90 % of the total volumecount of all particles analyzed
is represented.
4. Summary of Test Method
4.1 Test specimenspecimens are fed through the dynamic imaging instrument which is comprised of a camera sensor and
illumination source opposing each other to form a measurement zone where the fluid image is captured and then analyzed for
particle size and distribution. The particle size and size distribution values are based on the projected equivalent particle diameter.
Shape parameters can be used to identify air bubbles that may be present and eliminate them from the reported data. Other
appropriate parameters may be used as well. Likewise for undiluted paints (for example, clear paints), shape parameters can be
used to eliminate air bubbles and water droplets that may be present from the reported data. Shape parameter formulations may
differ from instrument to instrument.
5. Significance and Use
5.1 By following this test method, the particle size, particle size distribution and particle shape of particulates in liquid paint and
pigment dispersions can be measured.
5.2 Particle size, particle size distribution and particle shape have a great effect on the color, opacity and gloss of paints.
Reproducing these characteristics is critical to the quality and performance of the paint produced.
5.3 The dynamic imaging instrument is useful during manufacturing to detect oversize particles as well as the required size
distribution of particles in order to provide quality and consistency from batch to batch.
6. Interferences
6.1 Contaminated environmental conditions and poor handling techniques can easily contaminate the sample. Care must be taken
to ensure test results are not biased by introduced particles.
6.2 High concentrations of air bubbles, resulting from violent agitation, should be avoided. The software is designed to detect and
eliminate them from the data, however high concentrations can mask other particles.
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6.3 Steps should be taken to prevent the introduction of water into the paint. In undiluted paints, water droplets can be detected
and counted as particles giving false positive readings. The software is designed to identify free water droplets and eliminate them
from the data.
6.4 Samples may be diluted with an appropriate diluent per the instrument’sinstrument manufacturer’s instructions. This situation
may arise due to high viscosity levels or high concentrations of particles, droplets and bubbles present in the view which may cause
reporting errors. The software shall provide an alarm or error message if particle populations are too high for the instrument to
accurately measure particle size, particle size distribution or particle shape.
7. Apparatus
7.1 Dynamic Imaging Particle Analyzer, a particle counter, shape and size measuring instrument consisting of a flow through cell,
an image capture device, means of illumination and software and readout capabilities. Fig. 1 shows a typical gravity feed system.
7.2 Paint Shaker—any device manufactured to agitate and mix paints in their containers.
7.3 Instrument Stand.
7.4 Reservoir—to contain and mix paint in diluted or undiluted state. Holds up to two litres (2 L) of volume.
7.5 Agitator—to mix contents of reservoir. Should be capable of mixing paints with viscosities up to 1 kg/m s.
7.6 Inlet/Outlet Lines w/full flow shut off valves.
7.7 Drain Line.
Alternate Configurations
7.8 InjectionMetering Pump—a dilution fluid supply can be plumbed in at the location of the upstream shut off valve and used
as a counter flow to dilute and mix the paint in the reservoir. Controlling the flow of diluent dictates the degree of dilution of the
specimen that flows through the instrument.software controlled pump to supply dilution fluid to the sample leaving the reservoir
and prior to entering the analyzer. The software signals the metering pump to increase or decrease the diluent flow depending on
the particle area per image.
FIG. 1 Example Arrangement of a Flow Cell
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Alternate Configurations
7.9 Syringe Pump—where smaller sample volumes can be effectively analyzed due to transparency of the paint a syringe can be
used to sample the paint and a syringe pump can be used to propel it through the instrument.
7.10 Luer-Lok Syringe—a sterile syringe that can be easily and quickly connected into the feed line to the instrument.
7.11 These alternate configurations can be reviewed in Annex A1Appendix X1.
8. Reagents and Materials
8.1 Reticle, traceable to NIST or other widely recognized standards body. A 19 mm diameter reticle with 100 μm grids and 10 μm
subdivisions has been found to work well for use in calibrating instruments, however various size reticles may be used as
appropriate for the particular manufacturer’s instrument.
8.2 Solvent, preferably a fast drying reagent, filtered to 0.45 micron and compatible withfast drying, reagent grade, and suitable
for the particular paints being tested. For oil based paints mineral spirit has been found to work well for dilution and cleaning. For
water based paints water (8.3) has been found to work well for dilution and cleaning. Other common reagent grade solvents may
be used.
8.3 Water, ultra-pure, reagent grade.
8.4 Mono-Disperse Bead Standard, vendor certified to be >95%>95 % spherical and a coefficient of variance <10%. Ten micron
(10 μm) have been found to work well, however other sizes may also be used.<10 %. Sizes can be selected to represent the
expected range of particle distributions
8.4 NIST SRM 1982, or similar particle size distribution standard traceable to NIST or similar widely known body.
9. Sample Collection and Handling
9.1 Refer to Practice D3925 for proper sampling of paint and pigmented coatings for analysis.
9.2 Sample containers should be clearly marked identifying their contents at a minimum.
9.3 Sample volume should be per instrument manufacturer’s instructions. If particle concentration is too high (see 6.4) the
specimen may be diluted using an appropriate diluent filtered to(see 8.2 0.45or 8.3μm to remove contaminants.).
10. Preparing the Instrument
10.1 Clean the instrument with a compatible solvent, filtered to 0.45 μm, solvent by flushing the solvent through the instrument
under normal operating conditions. As solvent passes through the instrument measure it for particle content. Continue to flush with
fresh solvent until the particle count per mL of the solvent, as measured by the instrument, is well below normal particulate levels
for the paint to be tested.
11. Calibration and Verification
11.1 Calibration
11.1.1 Instruments must be calibrated by use of a reticle traceable to NIST or other similar standard body (see 8.1). If a difference
to the nominal size of particle size standard is recognized the instrument should be recalibrated. Calibration shall be performed
per the instrument’s manufacturer’s instructions at least every 12 months.
11.2 Verification
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11.2.1 Instrument calibration for size shall be verified at least every 12 months using mono-disperse beads to check (see 8.38.4).
The standard may be diluted with water, or other appropriate diluent (see 8.2), filtered to 0.45 μm, to to create a test specimen of
the correct volume for the instrument. Flow the specimen through the instrument analyzing particle size for the recommended
number of frames for analysis per the manufacturer’s instructions. Result of mean particle size analysis must be within 3%3 % of
the particle size standard’s manufacturer’s certified mean
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