ASTM D823-18(2022)
(Practice)Standard Practices for Producing Films of Uniform Thickness of Paint, Coatings and Related Products on Test Panels
Standard Practices for Producing Films of Uniform Thickness of Paint, Coatings and Related Products on Test Panels
SIGNIFICANCE AND USE
4.1 This practice should be used for those coatings that are designed for spray applications of objects in the factory or in the field. It is particularly important that it be used in the evaluation of metallic coatings for appearance properties, such as gloss and color.
4.2 Coatings applied by this test method may exhibit a slight orange-peel or spray wave.
SCOPE
1.1 Five practices are given for preparing films of uniform thickness of coatings on test panels. These practices are:
Practice A—Automated Spray Machine Application
Practice B—Motor-Driven Dip Coater Application
Practice C—Motor-Driven Blade Film Application
Practice D—Hand-Held Spray Gun Application
Practice E—Hand-Held Blade Film Application
1.2 The use of wire-wound drawdown bars as described in Practice D4147 may also be an appropriate method for producing films of uniform coating thickness.
1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.
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 use.
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: D823 − 18 (Reapproved 2022)
Standard Practices for
Producing Films of Uniform Thickness of Paint, Coatings
and Related Products on Test Panels
This standard is issued under the fixed designation D823; 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 Related Coating Products
D1005 Test Method for Measurement of Dry-Film Thick-
1.1 Five practices are given for preparing films of uniform
ness of Organic Coatings Using Micrometers
thickness of coatings on test panels. These practices are:
D1212 Test Methods for Measurement of Wet Film Thick-
Practice A—Automated Spray Machine Application
ness of Organic Coatings
Practice B—Motor-Driven Dip Coater Application
D3924 Specification for Standard Environment for Condi-
Practice C—Motor-Driven Blade Film Application
tioning and Testing Paint, Varnish, Lacquer, and Related
Practice D—Hand-Held Spray Gun Application
Materials
Practice E—Hand-Held Blade Film Application
D4147 Practice for Applying Coil Coatings Using Wire-
1.2 The use of wire-wound drawdown bars as described in
Wound Drawdown Bars
Practice D4147 may also be an appropriate method for
D4285 Test Method for Indicating Oil or Water in Com-
producing films of uniform coating thickness.
pressed Air
1.3 The values stated in SI units are to be regarded as the D4414 Practice for Measurement of Wet Film Thickness by
Notch Gages
standard. The values given in parentheses are for information
only. D7091 Practice for Nondestructive Measurement of Dry
Film Thickness of Nonmagnetic Coatings Applied to
1.4 This standard does not purport to address all of the
Ferrous Metals and Nonmagnetic, Nonconductive Coat-
safety concerns, if any, associated with its use. It is the
ings Applied to Non-Ferrous Metals
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
PRACTICE A—AUTOMATED SPRAY MACHINE
mine the applicability of regulatory limitations prior to use.
APPLICATION
1.5 This international standard was developed in accor-
dance with internationally recognized principles on standard-
3. Summary of Practices
ization established in the Decision on Principles for the
3.1 A liquid material is applied to a test panel by means of
Development of International Standards, Guides and Recom-
anautomatedspraymachineconsistingofamountedspraygun
mendations issued by the World Trade Organization Technical
and a panel holder. This machine can (1) move the panel
Barriers to Trade (TBT) Committee.
holder, with test panel, at a uniform speed through the
atomized spray produced by a fixed spray gun, or (2)itcan
2. Referenced Documents
move the gun, with atomized spray, at a uniform speed past the
2.1 ASTM Standards:
test panel(s) mounted on a fixed panel holder. A machine
D609 Practice for Preparation of Cold-Rolled Steel Panels
equipped with a programmable system can index the spray gun
for Testing Paint, Varnish, Conversion Coatings, and
vertically for multiple passes and for multiple coats with
selective time delay.
3.2 The thickness of coating applied is controlled by the
These practices are under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, and Applications and are the direct responsibility traverse speed of the panel or gun, the fluid delivery rate of the
of Subcommittee D01.23 on Physical Properties of Applied Paint Films.
gun,thesprayguntipsize,theviscosityofthematerial,andthe
Current edition approved June 1, 2022. Published June 2022. Originally
amount of nonvolatile matter in the material.
approved in 1945. Last previous edition approved in 2018 as D823 – 18. DOI:
10.1520/D0823-18R22.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or 4. Significance and Use
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
4.1 This practice should be used for those coatings that are
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. designed for spray applications of objects in the factory or in
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D823 − 18 (2022)
the field. It is particularly important that it be used in the spray gun. Reduce the material to a viscosity suitable for
evaluation of metallic coatings for appearance properties, such spraying using the coating manufacturer’s recommended thin-
as gloss and color. ner.
4.2 Coatingsappliedbythistestmethodmayexhibitaslight 7.3 Connect the container to the gun and test the spray gun
orange-peel or spray wave. operation while stationary, for correct spray pattern and uni-
formity by allowing a momentary spray to be deposited on a
5. Apparatus
piece of paper placed in the panel position. Adjust the air
pressure, material flow, and spray fan width controls until the
5.1 Test Panels, of any clean, planar rigid substrate with a
desired pattern and uniformity are obtained. Further refine-
uniform surface of a size that can be accommodated by the
ments may be made in the spray pattern by modifying the air
panel holder of the automated spray machine.
pressure, and the type and amount of thinner.
5.1.1 Whensteelpanelsareused,theyshouldbepreparedin
accordance with the appropriate method in Practice D609.
NOTE 4—The width of the spray pattern should be considerably wider
than the width of the test panel to assure spray uniformity on the test
5.2 Automated Spray Machine, equipped with a panel
panel.
holder and a mounting for a spray gun. The machine shall be
7.4 Place a test panel on the panel holder and start the
designed to move the panel holder at a uniform speed past the
machine. Operate the spray gun so that it will begin spraying a
fixed gun mount or designed to move the gun mount at a
few inches before the test panel enters the spray pattern and
uniform speed past the fixed panel holder. The panel holder or
continue spraying a few inches after the test panel leaves the
the gun mount traverse speed shall be adjustable from
spray pattern.
7.5 to 30 m (25 to 100 ft)/min. Examples of automated spray
machines are shown in Fig. 1.
7.5 Measure the wet film thickness in accordance with Test
Methods D1212 or Practice D4414. Additional passes may be
NOTE 1—Some automated spray machines provide additional features
that can improve the uniformity of film preparation. Some examples are: made until the desired wet film thickness has been achieved.
az-barpanelholder;indexingofthepanelholderatrightanglestothegun
7.6 Remove the coated panel and bake, force-dry, or air-dry
to provide uniform lapping; and automatic control of number of passes,
it, in accordance with its type, in a vertical position in a
time between passes, and lapping distance.
dust-free atmosphere (if required), as described in Specifica-
5.3 Spray Gun, any that will provide a uniform fan-type
tion D3924.
spray pattern at least 150 mm (6 in.) in width is satisfactory.
7.7 Measure the dry film thickness of the coating in accor-
The gun may be triggered manually or automatically.
dance with Test Methods D1005 or Practice D7091, whichever
5.4 Air Pressure Gage, covering the range of 0 to 690 kPa
is appropriate.
(0 to 100 psi).
5.5 Air Pressure Regulator.
8. Report
5.6 Air Supply, water and oil-free, under pressure.
8.1 Report the following information:
8.1.1 Type of coating material,
6. Preparation of Apparatus
8.1.2 Type and amount of thinner added as a percentage by
6.1 Mount the spray gun on the automated spray machine.
weight or volume of the total mixed coating, if applicable,
Connect the air line hose from the regulator to the air pressure
8.1.3 Temperature of coating material,
gagewhichinturnisconnectedtotheairinletofthespraygun.
8.1.4 Wet film thickness,
8.1.5 Distance of test panel from gun tip,
6.2 Set the gun so that its tip is at the desired distance from
the test panel surface, usually in the range from 200 to 300 mm 8.1.6 Type of spray gun and spray tip size,
8.1.7 Air pressure,
(8 to 12 in.).
8.1.8 Number of spray passes,
6.3 With the gun trigger fully open, adjust the air regulator
8.1.9 Traverse speed,
to provide the desired reading on the air pressure gage.
8.1.10 Air temperature, relative humidity and temperature
NOTE 2—A suitable air pressure is usually from 275 to 520 kPa (40 to
of test panel at time of application, and
75 psi).
8.1.11 Mean and range of dry film thickness values ob-
6.4 Set the automated spray machine controls to provide the
tained.
desired traverse speed of the panel holder or the gun mount,
PRACTICE B—MOTOR-DRIVEN DIP COATER
whichever is pertinent to the type of machine being used.
APPLICATION
NOTE3—Suitabletraversespeedsforautomotivecoatingsusuallyrange
from 17.5 to 22.5 m/min (700 to 900 in./min).
9. Summary of Practice
7. Procedure
9.1 Amotor-driven device is employed to withdraw the test
panel from a container of the coating material at a desired
7.1 If compressed air is used to atomize the coating, verify
that the air is clean and dry according to Test Method D4285. uniform rate.
7.2 If recommended by the coating manufacturer, strain the 9.2 The wet film thickness of the applied coating is influ-
material to be sprayed into the container to be used with the encedbymanyvariablesincluding,butnotlimitedtothespeed
D823 − 18 (2022)
(a) Fixed Gun, Traveling Panel Machine (b) Fixed Panel, Traveling Gun Machine
(c) Fixed Panel Programmable Indexing Traveling Gun Machine
FIG. 1 Automatic Spray Machines, Practice A
D823 − 18 (2022)
because the smaller exposed surfaces of the liquid coating reduces volatile
of withdrawal, rheological characteristics of the coating at the
loss.
test temperature and the temperature of the test panel.
11.2 Test Panels, of any clean, rigid substrate with a
10. Significance and Use
uniform surface of a size that can be accommodated by the dip
10.1 This test method is limited to those materials that flow coater and the container.
out to smooth films when test panels are dipped into the 11.2.1 When steel panels are used they shall be prepared in
material and withdrawn.
accordance with the appropriate method in Practice D609.
NOTE 6—The test panels should not exceed 300 mm (12 in.) in length,
11. Apparatus
but the width may be varied up to 300 mm (12 in.) if a suitable
11.1 Dip Coater, consisting of a mechanism that will with-
counterweight is used and a dip tank of adequate size is provided. Use of
a multiple hook will permit dipping several panels at one time.
draw a panel from a container of the coating material at a
predetermined rate. Suitable apparatus, is shown in Fig. 2(a)
12. Procedure
and 2(b):
11.1.1 The apparatus shown in Fig. 2(a) uses a cord wound
12.1 Adjust the coating material to the desired viscosity
around a step-cone pulley on the shaft of a motor to provide
using thinner as necessary. Measure the temperature of the
panel withdrawal rate of 50, 75, and 100-mm (2, 3, and
material in the container at the time of application.
4-in.)/min. Prior to withdrawal, the panel, attached to the cord,
NOTE 7—The operating conditions (viscosity, percent of nonvolatile
is lowered by hand into the container holding the material.
matter, and rate of withdrawal) are specific for a given coating material
11.1.2 The apparatus shown in Fig. 2(b) uses a cord driven
and film thickness and need to be determined by trial. Subsequent
by a variable-speed device that can provide panel immersion
reproduction of the same operating conditions should yield a similar film
and withdrawal rates that are continuously variable from 65 to
thickness.
510 mm (2.5 to 20 in.)/min.
12.2 Place the prepared test panel on the hook attached to
NOTE 5—Rectangular containers (F-style can with lid cut off) are useful the cord and lower it into the container holding the coating
(a) Dip-Coater With Motor-Driven Step-Cone Pulley (b) Dip-Coater With Continuously Variable Speed Drive
FIG. 2 Dip-Coater, Practice B
D823 − 18 (2022)
material. Wind the cord once completely around the pulley of 13.1.5 Air temperature, relative humidity and temperature
the correct size to give the desired rate of withdrawal. of test panel surface at time of application, and
12.2.1 For the stepped-cone pulley apparatus, wind the cord 13.1.6 Mean and range of dry film thickness values ob-
once completely around the pulley of the correct size to give tained.
the desired weight of withdrawal.
PRACTICE C—MOTOR-DRIVEN BLADE FILM
12.2.2 For the continuously variable speed apparatus set the
APPLICATION
desired panel immersion and withdrawal rates on the control
panel.
14. Summary of Practice
12.3 Start the motor and withdraw the panel at the desired
14.1 Auniform film is produced by an applicator blade that
rate, with a smooth movement entirely free of vibration.
is pushed or pulled across the test panel at a uniform speed by
12.4 MeasurethewetfilmthicknessinaccordancewithTest
a motor-driven device.
Methods D1212 or Practice D4414.
14.2 The wet film thickness of the coating applied may be
12.5 Bake, force-dry, or air-dry the coated panel, in accor-
affected by the speed at which the applicator blade is moved,
dance with its type, in a vertical position in a dust-free
the clearance of the applicator blade, the design of the
atmosphere in accordance with Specification D3924. Measure
applicator blade, and the viscosity of the coating.
the dry film thickness of the coating in accordance with Test
Method D1005 or Practice D7091.
15. Significance and Use
12.6 If the coating thickness is too low, coat another panel
15.1 This test method is applicable to substrates consisting
using a slower rate of panel withdrawal. If the coating
of uniform rigid materials, such as metal or glass, and of
thickness is too high, coat another panel using a faster rate of
non-rigid materials, such as paper charts. The motor-driven
panel withdrawal.
film applicator may offer advantages over the use of hand-held
12.7 Continue in this manner until a test panel having the
film applicator blade, due to the constant speed of application.
desired film thickness is produced. Measure thickness on at
least three different areas of the test panel to determine coating
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