ASTM D2793-99(2005)
(Test Method)Standard Test Method for Block Resistance of Organic Coatings on Wood Panel Substrates
Standard Test Method for Block Resistance of Organic Coatings on Wood Panel Substrates
SIGNIFICANCE AND USE
Coated wood panel products must be stacked face to face or face to back during warehousing, packaging, and transportation without the coated finish sticking (blocking) and becoming damaged. This test method describes a laboratory means of evaluating conditions of blocking using factors of pressure, heat, time and moisture.
Degrees of hardness or degrees of cure of organic coatings, or both, can be evaluated using a blocking test.
The rate of volatile loss (drying speed) of organic coatings can be evaluated using a blocking test.
The effectiveness of protective packaging materials (slip sheets) for organic coatings on wood substrates can be evaluated using a blocking test.
SCOPE
1.1 This test method covers the determination of the block resistance of organic coatings on wood and wood-based panel substrates. Block resistance is the ability of a coating to resist sticking to another surface and to resist any change in appearance when it is pressed against that surface for a prolonged period of time.
1.2 General methods for determining block resistance are outlined in Sections 6 and 7. Variations inherent in user materials and procedures, however, may dictate adjustments to the general method to improve accuracy. Paragraphs 7.3 and 7.4 provide guidelines for tailoring the general procedure to a user's specific application. Paragraph 7.5 offers a rating methodology.
1.3 Test Method D 2091 should be used for the determination of print resistance or pressure mottling of organic coatings, particularly lacquers, applied to wood-based case goods such as furniture.
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 and health practices and determine the applicability of regulatory limitations prior to use.
General Information
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Standards Content (Sample)
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Designation:D2793–99(Reapproved2005)
Standard Test Method for
Block Resistance of Organic Coatings on Wood Panel
Substrates
This standard is issued under the fixed designation D2793; 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 3. Summary of Test Method
1.1 This test method covers the determination of the block 3.1 The coatings are prepared for testing in a manner
resistance of organic coatings on wood and wood-based panel duplicating production application and curing conditions as
substrates. Block resistance is the ability of a coating to resist nearlyaspossibleonthespecifiedwoodsubstrate.Thenastack
sticking to another surface and to resist any change in of these painted substrates is formed and subjected to a
appearance when it is pressed against that surface for a specified pressure and temperature for a sufficient time to
prolonged period of time. develop any sticking tendencies that exist. The pressure is
1.2 General methods for determining block resistance are released and the painted surfaces are examined for any signs of
outlined in Sections 6 and 7. Variations inherent in user sticking or pressure mottling. If blocking (forming a block by
materials and procedures, however, may dictate adjustments to panels sticking together) occurs, the material is unsatisfactory.
the general method to improve accuracy. Paragraphs 7.3 and If no sticking or damage to the film surface occurs, the material
7.4 provide guidelines for tailoring the general procedure to a is satisfactory.
user’s specific application. Paragraph 7.5 offers a rating meth- 3.2 When the conditions of production finishing are estab-
odology. lishedandknown,themethodofapplication,thesubstrate,film
1.3 Test Method D2091 should be used for the determina- thickness, and cure of the film should duplicate these condi-
tionofprintresistanceorpressuremottlingoforganiccoatings, tions as closely as possible. However, some acceleration of the
particularly lacquers, applied to wood-based case goods such test may be possible with more severe conditions.
as furniture.
4. Significance and Use
1.4 The values stated in SI units are to be regarded as the
4.1 Coated wood panel products must be stacked face to
standard. The values given in parentheses are for information
only. face or face to back during warehousing, packaging, and
transportation without the coated finish sticking (blocking) and
1.5 This standard does not purport to address all of the
safety concerns, if any, associated with its use. It is the becoming damaged. This test method describes a laboratory
means of evaluating conditions of blocking using factors of
responsibility of the user of this standard to establish appro-
priate safety and health practices and determine the applica- pressure, heat, time and moisture.
4.2 Degrees of hardness or degrees of cure of organic
bility of regulatory limitations prior to use.
coatings, or both, can be evaluated using a blocking test.
2. Referenced Documents
4.3 The rate of volatile loss (drying speed) of organic
2.1 ASTM Standards: coatings can be evaluated using a blocking test.
D2091 Test Method for Print Resistance of Lacquers 4.4 The effectiveness of protective packaging materials (slip
sheets) for organic coatings on wood substrates can be evalu-
ated using a blocking test.
This test method is under the jurisdiction of ASTM Committee D01 on Paint
and Related Coatings, Materials, andApplications and is the direct responsibility of
5. Apparatus
Subcommittee D01.52 on Factory Coated Wood Products.
Current edition approved May 15, 2005. Published June 2005. Originally
5.1 Hydraulic Press (preferably constant pressure), ca-
approved in 1969. Last previous edition approved in 1999 as D2793 – 99. DOI:
pable of maintaining the agreed upon stacking pressure.
10.1520/D2793-99R05.
2 5.2 Rigid Platens, at least 4 in. (100 mm) square, capable of
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 being maintained at the desired test temperature.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
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D2793–99 (2005)
6. Test Specimens
A = stack area,
A = support area, and
6.1 For those cases where the intended use conditions are 2
F = safety factor.
not established or known, the following specifications or some
set of specifications agreed upon between the purchaser and Support area is difficult to establish precisely. In practice,
seller apply: stacking may be directly on the floor, or support stringers may
6.1.1 The test coating shall be applied by spray to a panel. be used. As stringers increase stacking pressures substantially,
6.1.2 The panel shall be a piece of 6.4 mm ( ⁄4 in.) smooth this should be compensated for by use of higher platen
two side (S2S) standard hardboard or other thickness and type pressures or by the inclusion of stringer rods in the sample
of wood substrate. stack.
6.1.3 The dry film thickness of pigmented coatings shall be
7.4 If the presence of water between substrate surfaces can
1.5 6 0.2 mils (38 6 5 µm), and of clear coatings, shall be 30
belogicallyanticipatedasaresultofthemanufacturingprocess
6 5 µm (1.2 6 0.2 mils) or other agreed upon film thickness.
or storage conditions, include it in the procedure, as blocking
Cure of the coating shall be as agreed and should be standard-
tendencies may be altered. Systematic coated surface wetting
ized for each coating.
prior to test such as contact with saturated toweling, or
conditioning at elevated relative humidity conditions, can be
NOTE 1—Film thickness can be measured by weight differences before
and after painting, but this requires careful conditioning of the substrate useful in improving test efficacy.
under standard temperature and humidity conditions prior to each weigh-
7.5 At test conclusion, open the press and pick up the stack
ing. Film thickness can also be determined by using an aluminum tab
in such a fashion that first the bottom panel, then the next to
alongside the test panel and measuring the film thickness with a standard
bottom panel, and eventually all the panels are allowed to free
eddy-current gage or using a steel panel with a magnetic film thickness
fall of their own weight. Sample pairs that do not separate via
ga
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