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Designation: D 4946 – 89 (Reapproved 1999)
AMERICAN SOCIETY FOR TESTING AND MATERIALS
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Reprinted from the Annual Book of ASTM Standards. Copyright ASTM
Standard Test Method for
Blocking Resistance of Architectural Paints1
This standard is issued under the fixed designation D 4946; 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.
1. Scope 5. Significance and Use
1.1 This test method describes an accelerated procedure for 5.1 Dry paint often comes in contact with itself especially in
evaluating the face-to-face blocking resistance of trades sales window and door areas and, depending on its hardness, the
paints. This is not to be confused with blocking resistance Test pressure, temperature, humidity, and duration of time the
Method D 3003 which is concerned with blocking of industrial surfaces are in contact, sometimes sticks to itself (blocks). This
coatings on metal substrates, nor with Test Method D 2793 stringent test method can be used to compare and rate
which is concerned specifically with wood product finishes and subjectively the resistance of paints to blocking.
reports results on a satisfactory or not satisfactory basis, rather
than by the degree of blocking tendency as in this test method. 6. Apparatus
1.2 The values stated in the SI units of measurement are to 6.1 Conditioned Room, at 18 to 29.5°C (65 to 85°F ) and 40
be regarded as the standard. The values given in parentheses to 60 % relative humidity.
are for information only. 6.2 Sealed Paper Test Charts, approximately 190 by 280
1.3 This standard does not purport to address all of the mm (7.5 by 11 in.).
safety concerns, if any, associated with its use. It is the 6.3 Applicator Blade, 13 to 15 cm (5 to 6 in.) wide,
iTeh Standards
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica-
0.15–mm (6–mil) clearance.
6.4 Oven, 48 to 52°C (115 to 125°F ).
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bility of regulatory limitations prior to use. 6.5 Rubber Stoppers, No. 8, 3.2 cm (1.25 in.) smaller
diameter.
2. Referenced Documents 6.6 Weights, 1000 g.
2.1 ASTM Standards:
Document Preview
D 2793 Test Method for Block Resistance of Organic Coat-
6.7 Scissors.
6.8 Aluminum Tray or Pan, flat.
ings on Wood Substrates2
D 3003 Test Method for Pressure Mottling and Blocking 7. Procedure
ASTM 2
D4946-89(1999)
Resistance of Organic Coatings on Metal Substrates 7.1 Cast the paint to be tested on a sealed test chart using the
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applicator blade. Condition coated panels in the conditioned
3. Terminology room for seven days. All painted panels should be kept free of
3.1 Definition: grease, oil, or fingerprints since these will affect block resis-
3.1.1 blocking—The undesirable sticking together of two tance.
painted surfaces when pressed together or placed in contact 7.2 After the panels have been conditioned, cut out six 3.8
with each other for an extended period of time. by 3.8-cm (11⁄2 by 11⁄2-in. ) sections from the painted chart.
Start the cut at least 1.3 cm (1⁄2 in. ) away from the edge of the
4. Summary of Test Method drawdown.
4.1 Dried paint films are placed face-to-face and a pressure 7.3 Place the cut sections with the paint surfaces face-to-
of about 127 g/cm2(1.8 psi ) is applied. These paint films are face for each paint to be tested.
put into an oven for 30 min to make the test more stringent. 7.4 The weights, stoppers, and tray should be temperature
After cooling, the blocked panels are peeled apart. The degree equilibrated in the oven prior to running the test.
of blocking is rated subjectively for tack or seal using a series 7.5 Place the face-to-face specimens in the oven on a flat
of standard descriptive terms corresponding to numerical aluminum tray. Place a No. 8 stopper on top, with the small
ASTM values of 10 to 0. diameter in contact with the specimens, then place a 1000-g
weight on top of the stopper. This results in a pressure of 127
1
g/cm2(1.8 psi) on the specimens. One weight and stopper is to
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
and Related Coatings, Materials, and Applications and is the direct responsibility of
be used for each specimen to be tested. It is recommended that
Subcommittee D01.42 on Architectural Finishes. “pass’’ and “fail’’ paint controls be used in each test run and
Current edition approved May 26, 1989. Published July 1989. that the tests be run in triplicate.
2
Annual Book of ASTM Standards, Vol 06.02.
