ASTM D823-95

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Designation: D 823 – 95
AMERICAN SOCIETY FOR TESTING AND MATERIALS
100 Barr Harbor Dr., West Conshohocken, PA 19428
Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Practices for
Producing Films of Uniform Thickness of Paint, Varnish,
and Related Products on Test Panels
This standard is issued under the fixed designation D 823; 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 (e) indicates an editorial change since the last revision or reapproval.
This standard has been approved for use by agencies of the Department of Defense.
1. Scope PRACTICE A—AUTOMATIC SPRAY MACHINE
APPLICATION
1.1 Five practices are given for preparing films of uniform
thickness of coatings on test panels. These practices are:
3. Summary of Practices
Practice A—Automatic Spray Machine Application
3.1 A liquid material is applied to a test panel by means of
Practice B—Motor-Driven Dip Coater Application
an automatic spray machine consisting of a mounted spray gun
Practice C—Motor-Driven Blade Film Application
and a panel holder. This machine can (1) move the panel
Practice D—Hand-Held Spray Gun Application
holder, with test panel, at a uniform speed through the
Practice E—Hand-Held Blade Film Application
atomized spray produced by a fixed spray gun, or (2)itcan
1.2 The values stated in inch-pound units are to be regarded
move the gun, with atomized spray, at a uniform speed past the
as the standard. The values given in parentheses are for
test panel mounted on a fixed panel holder. A machine
information only.
equipped with a programmable system can index the spray gun
1.3 This standard does not purport to address all of the
vertically for multiple passes and for multiple coats with
safety concerns, if any, associated with its use. It is the
selective time delay.
responsibility of the user of this standard to establish appro-
3.2 The thickness of coating applied is controlled by the
priate safety and health practices and determine the applica-
traverse speed of the panel or gun, the fluid delivery rate of the
bility of regulatory limitations prior to use.
gun, the viscosity of the material, and the amount of nonvola-
2. Referenced Documents tile matter in the material.
2.1 ASTM Standards:
4. Significance and Use
D 609 Practice for Preparation of Cold-Rolled Steel Panels
4.1 These practices should be used for those coatings that
for Testing Paint, Varnish, Conversion Coatings, and
2 are designed for spray applications of objects in the factory or
Related Coating Products
in the field. It is particularly important that it be used in the
D 1005 Test Methods for Measurement of Dry Film Thick-
2 evaluation of metallic coatings for appearance properties, such
ness of Organic Coatings Using Micrometers
as gloss and color.
D 1186 Test Methods for Nondestructive Measurement of
4.2 Coatings applied by this test method may exhibit a slight
Dry Film Thickness of Nonmagnetic Coatings Applied to
orange-peel or spray wave.
a Ferrous Base
D 1212 Test Methods for Measurement of Wet Film Thick-
5. Apparatus
ness of Organic Coatings
5.1 Test Panels, of any smooth, planar material of a size that
D 1400 Test Method for Nondestructive Measurement of
can be accommodated by the panel holder of the automatic
Dry Film Thickness of Nonconductive Coatings Applied to
spray machine.
a Nonferrous Metal Base
5.1.1 When steel panels are used, they should be prepared in
D 3924 Specification for Standard Environment for Condi-
accordance with the appropriate method in Practice D 609.
tioning and Testing Paint, Varnish, Lacquer and Related
2 5.2 Automatic Spray Machine, equipped with a panel
Materials
holder and a mounting for a spray gun. The machine shall be
designed to move the panel holder at a uniform speed past the
fixed gun mount, or designed to move the gun mount at a
These practices are under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, and Applications and are the direct responsibility
of Subcommittee D01.23 on Physical Properties of Applied Paint Films.
Machines suitable for this purpose are manufactured by Eclipse Systems, Inc.,
Current edition approved Nov. 10, 1995. Published January 1996. Originally
12 Cork Hill Rd., Franklin, NJ 07416; Spraymation, Inc., 5320 N.W. 35th Ave., Ft.
published as D 823 – 45 T. Last previous edition D 823 – 92a.
Lauderdale, FL 33309-6314; and Sheen Instruments Ltd., 8 Waldegrave Road,
Annual Book of ASTM Standards, Vol 06.01.
Teddington, Middlesex, TW118LD, England.
D 823
that can improve the uniformity of film preparation. Some examples are:
uniform speed past the fixed panel holder. The panel holder or
a z-bar panel holder; indexing of the panel holder at right angles to the gun
the gun mount traverse speed shall be adjustable from 25 to
to provide uniform lapping; and automatic control of number of passes,
100 ft (7.5 to 30 m)/min. Typical machines are shown in
time between passes, and lapping distance.
Fig. 1.
5.3 Spray Gun, any that will provide a uniform fan-type
NOTE 1—Some automatic spray machines provide additional features
(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
D 823
spray pattern at least 6 in. (150 mm) in width is satisfactory. 8.1.5 Number of spray passes,
The gun may be triggered manually or automatically. 8.1.6 Traverse speed,
5.4 Pressure Gage, covering the range of 0 to 100 psi (0 to 8.1.7 Temperature and relative humidity at time of applica-
690 kPa). tion, and
5.5 Air Pressure Regulator. 8.1.8 Film thickness values obtained for applied coating.
5.6 Air Supply, oil-free, under pressure.
PRACTICE B—MOTOR-DRIVEN DIP COATER
6. Preparation of Apparatus
APPLICATION
6.1 Mount the spray gun on the automatic spray machine.
9. Summary of Practice
Connect the air line hose from the regulator to the air pressure
gage which in turn is connected to the air inlet of the spray gun.
9.1 A motor-driven device is employed to withdraw the test
6.2 Set the gun so that its tip is at the desired distance from
panel from a container of the coating material at a desired
the test panel surface, usually in the range from 8 to 12 in. (200
uniform rate.
to 300 mm).
9.2 The thickness of coating applied is controlled by the
6.3 With the gun trigger fully open, adjust the air regulator
speed of panel withdrawal, the viscosity of the material, and
to provide the desired reading on the air pressure gage.
the percent of solids in the material.
NOTE 2—A suitable air pressure is usually from 40 to 75 psi (275 to 520
10. Significance and Use
kPa).
10.1 This test method is limited to those materials that flow
6.4 Set the automatic spray machine controls to provide the
out to smooth films when test panels are dipped into the
desired traverse speed of the panel holder or the gun mount,
material and withdrawn.
whichever is pertinent to the type of machine being used.
11. Apparatus
NOTE 3—Suitable traverse speeds for automative coatings usually
range from 700 to 900 in./min (17.5 to 22.5 m/min). 4
11.1 Dip Coater, consisting of a mechanism that will
withdraw a panel from a container of the coating material at a
7. Procedure
predetermined rate. Suitable apparatus, is shown in Fig. 2(a)
7.1 Strain the material to be sprayed into the container to be
and 2(b):
used with the spray gun. Reduce the material to a viscosity
11.1.1 The apparatus shown in Fig. 2(a) uses a cord wound
suitable for spraying.
around a step-cone pulley on the shaft of a motor to provide
7.2 Connect the container to the gun and test the spray gun
panel withdrawal rate of 2, 3, and 4-in. (50, 75, and 100-mm)/
operation while stationary, for correct spray pattern and uni-
min. Prior to withdrawal, the panel, attached to the cord, is
formity by allowing a momentary spray to be deposited on a
lowered by hand into the container holding the material.
piece of paper placed in the panel position. Adjust the air
11.1.2 The apparatus shown in Fig. 2(b) uses a cord driven
pressure material flow, and spray fan width controls until the
by a variable-speed device that can provide panel immersion
desired pattern and uniformity are obtained. Further refine-
and withdrawal rates that are continuously variable from 2.5 to
ments may be made in the spray pattern by modifying the air
20 in. (65 to 510 mm)/min.
pressure, the type of thinning agent, and the consistency of the
NOTE 5—Rectangular containers (F-style can with lid cut off) are useful
material.
because the smaller exposed surfaces of the liquid coating reduces volatile
NOTE 4—The width of the spray pattern should be considerably wider
loss.
than the width of the test panel to assure spray uniformity on the test
11.2 Test Panels, of any clean, smooth, rigid substrate of a
panel.
size that can be accommodated by the dip coater and the
7.3 Place a test panel on the panel holder and start the
container.
machine. Operate the spray gun so that it will begin spraying a
11.2.1 When steel panels are used they shall be prepared in
few seconds before the test panel enters the spray pattern and
accordance with the appropriate method in Methods D 609.
continue spraying a few seconds after the test panel leaves the
NOTE 6—The test panels should not exceed 12 in. (300 mm) in length,
spray pattern.
but the width may be varied up to 12 in. if a suitable counterweight is used
7.4 Remove the coated panel and bake, force-dry, or air-dry
and a dip tank of adequate size is provided. Use of a multiple hook will
it, in accordance with its type, in a vertical position in a
permit dipping several panels at one time.
dust-free atmosphere, as described in Specification D 3924.
7.5 Determine the thickness of the coating in accordance
12. Procedure
with Test Methods D 1005, D 1186, D 1212, or D 1400,
12.1 Adjust the coating material to the proper percentage of
whichever is appropriate.
solids and viscosity. Measure the temperature of the material in
the container at the time of application.
8. Report
8.1 Report the following information:
8.1.1 Type of coating material,
Suitable dip coaters are the Gardco Dip Coater obtainable from Paul N. Gardner
8.1.2 Viscosity and percent of nonvolatile coating material,
Co., Inc., 316 N.E. First St., P.O. Box 10688, Pompano Beach, FL 33061-6688 and
8.1.3 Distance of test panel from gun tip,
the Dipcoater obtainable from Technical Equipment Co., P.O. Box 208, Willoughby,
8.1.4 Air pressure, OH 44094.
D 823
(a) Dip-Coater With Motor-Driven Step-Cone Pulley (b) Dip-Coater With Continuously Variable Speed Drive
FIG. 2 Dip-Coater, Practice B
NOTE 7—The operating conditions (viscosity, percent of nonvolatile
type, in a vertical position in a dust-free atmosphere in
matter, and rate of withdrawal) are specific for a given coating material
accordance with Specification D 3924.
and film thickness and need to be determined by trial. Subsequent
12.4 Determine the thickness of the coating in accordance
reproduction of the same operating conditions should give the same film
with Test Methods D 1005, D 1186, or D 1400, whichever is
thickness. Data are available on a variety of materials and film thickness
appropriate.
to indicate the range required. The viscosity range for normal film
12.5 If the coating thickness is too low, coat another panel
thickness of 0.5 to 2.0 mil (13 to 50 mm) has been shown to be 1 to
2.5 P. using a slower rate of panel withdrawal. If the coating
thickness is too high, coat another panel using a faster rate of
12.2 Place the prepared test panel on the hook attached to
panel withdraw.
the cord and lower it into the container holding the coating
12.6 Continue in this manner until a test panel having the
material. Wind the cord once completely around the pulley of
desired film thickness is produced. Measure thickness on at
the correct size to give the desired rate of withdrawal.
least three different areas of the test panel to determine coating
12.2.1 For the stepped-cone pulley apparatus, wind the cord
uniformity.
once completely around the pulley of the correct size to give
the desired weight of withdrawal.
NOTE 8—With the dip coater, non-uniform thickness on a panel is
12.2.2 For the continuously variable speed apparatus set the frequently obtained. Hence, if the film thickness is greater at the bottom
than the top, the viscosity should be increased or the panel withdrawal
desired panel immersion and withdrawal rates on the control
speed should be reduced, or both.
panel.
12.3 Start the motor and withdraw the panel at the desired
13. Report
rate, with a smooth movement entirely free of vibration. Bake,
13.1 Report the following information:
force-dry, or air-dry the coated panel, in accordance with its
13.1.1 Type of coating material,
13.1.2 Viscosity, temperature, and percent nonvolatile of
coating material,
Information covering viscosity, percent of solids, rates of withdrawal and film
13.1.3 Rate of withdrawal,
thickness for a variety of finishing materials is given in the paper by Payne, H. F.,
13.1.4 Air temperature and relative humidity at time of
“The Dip Coater, An Instrument For Making Uniform Films by the Dip Method,”
Industrial and Engineering Chemistry, Analytical Edition, Vol 15, 1943, p. 48. application, and
D 823
FIG. 3 Blade Film Applicator, Motor-Driven, Practice C
13.1.5 Mean and range of dry film thickness values ob- 16.3 Applicator Blade, any common type, either with ad-
tained. justable or fixed clearances.
16.4 Test Panels, any clean, smooth, rigid substrate or may
PRACTICE C—MOTOR-DRIVEN BLADE FILM
be paper charts or similar materials.
APPLICATION
NOTE 9—Rigid panels shall be cleaned in an approved manner. Steel
panels shall be prepared in accordance with the appropriate method in
14. Summary of Practice
Practice D 609.
14.1 A uniform film is produced by an applicator blade that
17. Procedure
is pushed across the test panel at a uniform speed by a
motor-driven device.
17.1 Clean the base plate and place the test panel on it.
14.2 The thickness of coating applied is controlled by the
17.2 If a vacuum is needed to hold the test panel flat,
clearance of the applicator blade and the viscosity and percent-
connect the vacuum source to the base plate and turn it on.
age of solids of the material.
NOTE 10—When films are being applied to paper charts or tin foil, a
sheet of paper should first be placed on the vacuum plate to prevent
15. Significance a
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