ASTM D2793-99(2024)

Standard Test Method for Block Resistance of Organic Coatings on Wood Panel Substrates

SIGNIFICANCE AND USE
4.1 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.  
4.2 Degrees of hardness or degrees of cure of organic coatings, or both, can be evaluated using a blocking test.  
4.3 The rate of volatile loss (drying speed) of organic coatings can be evaluated using a blocking test.  
4.4 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 D2091 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.6 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

• Status: Published
• Publication Date: 31-Jan-2024
• ICS: 25.220.60 - Organic coatings
• Technical Committee: D01 - Paint and Related Coatings, Materials, and Applications
• Drafting Committee: D01.52 - Factory Coated Wood Products

Relations

• Replaces: ASTM D2793-99(2017) - Standard Test Method for Block Resistance of Organic Coatings on Wood Panel Substrates
• Effective Date: 01-Feb-2024
• Refers: ASTM D2091-96(2024) - Standard Test Method for Print Resistance of Lacquers
• Effective Date: 01-Feb-2024
• Refers: ASTM D2091-96(2017) - Standard Test Method for Print Resistance of Lacquers
• Effective Date: 01-Jul-2017
• Referred By: ASTM D4946-89(2017) - Standard Test Method for Blocking Resistance of Architectural Paints
• Effective Date: 01-Feb-2024
• Referred By: ASTM D3732-23 - Standard Practice for Reporting Cure Times of Ultraviolet-Cured Coatings
• Effective Date: 01-Feb-2024
• Referred By: ASTM D3451-06(2017) - Standard Guide for Testing Coating Powders and Powder Coatings
• Effective Date: 01-Feb-2024

Overview

ASTM D2793-99(2024), titled Standard Test Method for Block Resistance of Organic Coatings on Wood Panel Substrates, establishes a recognized laboratory procedure for evaluating the block resistance of organic coatings such as paints, varnishes, and lacquers applied to wood and wood-based panel substrates. Block resistance refers to a coating’s ability to resist sticking to another surface under conditions of pressure, heat, moisture, and time, which could otherwise lead to surface damage or impaired finish.

Correct assessment of a coating’s block resistance is essential for manufacturers, suppliers, and end-users of finished wood products. This ensures that coatings maintain their appearance and integrity during critical phases such as factory finishing, warehousing, packaging, transportation, and end-use, where stacked panels may experience prolonged contact.

Key Topics

• Block Resistance Testing: This standard outlines laboratory methods for testing the tendency of coated panels to stick together or transfer appearance defects when subjected to stacking pressure, elevated temperature, and humidity.
• Test Variables: Key factors assessed include pressure, heat, time, and moisture, simulating real-world handling and storage conditions for coated wood products.
• Evaluation of Coating Performance: The method also evaluates the degree of cure or hardness of the organic coating, as well as the drying rate (volatile loss) and the effectiveness of protective packaging materials such as slip sheets.
• Flexible Methodology: The standard allows users to adjust testing conditions to closely reflect their particular materials and procedures, with guidelines for reproducibility and result rating systems.
• Reporting and Safety: Detailed reporting requirements ensure transparency, while users remain responsible for observing applicable health, safety, and environmental protocols.

Applications

This ASTM test method provides practical value across a wide range of industries where coated wood products are produced, finished, transported, or assembled, such as:

• Furniture Manufacturing: Ensuring finished surfaces of tables, cabinets, and case goods are resistant to sticking and marking when stored in stacks.
• Flooring and Architectural Panels: Maintaining surface integrity of factory-coated wood panels during shipment and installation.
• Wood Product Packaging: Assessing and selecting effective slip sheets and interleaving materials to minimize surface damage during storage and transit.
• Quality Control in Coating Production: Providing reliable procedures for R&D, product qualification, and routine quality inspection of organic coatings.
• Performance Evaluation: Offering a basis to compare different coating formulations, curing methods, and application techniques for optimal block resistance and product durability.

By following ASTM D2793-99(2024), manufacturers and specifiers can safeguard product quality, reduce claims and rework, and satisfy customer expectations for visually flawless finished wood substrates.

Related Standards

• ASTM D2091 - Standard Test Method for Print Resistance of Lacquers (particularly applicable for evaluating pressure mottling or print resistance on coated wood case goods)
• ASTM Standards for Paints and Coatings - Additional methods exist for evaluating various performance aspects, including adhesion, hardness, and chemical resistance.
• ISO Standards for Wood and Coatings - International guidance on finished wood product evaluation.
• WTO TBT Principles - Developed in alignment with the World Trade Organization’s Technical Barriers to Trade Committee’s recognized standardization principles.

Keywords: block resistance, organic coatings, wood substrates, ASTM D2793, paint, lacquer, varnish, slip sheets, quality control, coating performance, finished wood panels, packaging materials.

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: D2793 − 99 (Reapproved 2024)
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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This test method covers the determination of the block
D2091 Test Method for Print Resistance of Lacquers
resistance of organic coatings on wood and wood-based panel
substrates. Block resistance is the ability of a coating to resist
3. Summary of Test Method
sticking to another surface and to resist any change in
3.1 The coatings are prepared for testing in a manner
appearance when it is pressed against that surface for a
duplicating production application and curing conditions as
prolonged period of time.
nearly as possible on the specified wood substrate. Then a stack
1.2 General methods for determining block resistance are
of these painted substrates is formed and subjected to a
outlined in Sections 6 and 7. Variations inherent in user
specified pressure and temperature for a sufficient time to
materials and procedures, however, may dictate adjustments to
develop any sticking tendencies that exist. The pressure is
the general method to improve accuracy. Paragraphs 7.3 and
released and the painted surfaces are examined for any signs of
7.4 provide guidelines for tailoring the general procedure to a sticking or pressure mottling. If blocking (forming a block by
user’s specific application. Paragraph 7.5 offers a rating meth-
panels sticking together) occurs, the material is unsatisfactory.
odology. If no sticking or damage to the film surface occurs, the material
is satisfactory.
1.3 Test Method D2091 should be used for the determina-
3.2 When the conditions of production finishing are estab-
tion of print resistance or pressure mottling of organic coatings,
lished and known, the method of application, the substrate, film
particularly lacquers, applied to wood-based case goods such
thickness, and cure of the film should duplicate these condi-
as furniture.
tions as closely as possible. However, some acceleration of the
1.4 The values stated in SI units are to be regarded as the
test may be possible with more severe conditions.
standard. The values given in parentheses are for information
4. Significance and Use
only.
4.1 Coated wood panel products must be stacked face to
1.5 This standard does not purport to address all of the
face or face to back during warehousing, packaging, and
safety concerns, if any, associated with its use. It is the
transportation without the coated finish sticking (blocking) and
responsibility of the user of this standard to establish appro-
becoming damaged. This test method describes a laboratory
priate safety, health, and environmental practices and deter-
means of evaluating conditions of blocking using factors of
mine the applicability of regulatory limitations prior to use.
pressure, heat, time and moisture.
1.6 This international standard was developed in accor-
4.2 Degrees of hardness or degrees of cure of organic
dance with internationally recognized principles on standard-
coatings, or both, can be evaluated using a blocking test.
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- 4.3 The rate of volatile loss (drying speed) of organic
mendations issued by the World Trade Organization Technical coatings can be evaluated using a blocking test.
Barriers to Trade (TBT) Committee.
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, and Applications and is the direct responsibility of
Subcommittee D01.52 on Factory Coated Wood Products. For referenced ASTM standards, visit the ASTM website, www.astm.org, or
Current edition approved Feb. 1, 2024. Published February 2024. Originally contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
approved in 1969. Last previous edition approved in 2017 as D2793 – 99 (2017). Standards volume information, refer to the standard’s Document Summary page on
DOI: 10.1520/D2793-99R24. the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D2793 − 99 (2024)
5. Apparatus substrates. Where no procedure exists, approximations may be
made using a calculation of production stacking pressure, as
5.1 Hydraulic Press (preferably constant pressure), capable
follows:
of maintaining the agreed upon stacking pressure.
DHA /A × F (1)
~ !
1 2
5.2 Rigid Platens, at least 4 in. (100 mm) square, capable of
being maintained at the desired test temperature.
where:
D = board density,
6. Test Specimens
H = stack height,
6.1 For those cases where the intended use conditions are A = stack area,
A = support area, and
not established or known, the following specifications or some
F = safety factor.
set of specifications agreed upon between the purchaser and
seller apply:
Support area is difficult to establish precisely. In practice,
6.1.1 The test coating shall be applied by spray to a panel.
stacking may be directly on the floor, or support stringers may
6.1.2 The panel shall be a piece of 6.4 mm ( ⁄4 in.) smooth
be used. As stringers increase stacking pressures substantially,
two side (S2S) standard hardboard or other thickness and type
this should be compensated for by use of higher platen
of wood substrate.
pressures or by the inclusion of stringer rods in the sample
6.1.3 The dry film thickness of pigmented coatings shall be
stack.
1.5 mils 6 0.2 mils (38 μm 6 5 μm), and of clear coatings,
7.4 If the presence of water between substrate surfaces can
shall be 30 μm 6 5 μm (1.2 mils 6 0.2 mils) or other agreed
be logically anticipated as a result of the manufacturing process
upon film thickness. Cure of the coating shall be as agreed and
or storage conditions, include it in the procedure, as blocking
should be standardized for each coating.
tendencies may be altered. Systematic coated surface wetting
NOTE 1—Film thickness can be measured by weight differences before
prior to test such as contact with saturated toweling, or
and after painting, but this requires careful conditioning of the substrate
conditioning at elevated relative humidity conditions, can be
under standard temperature and humidity conditions prior to each weigh-
useful in improving test efficacy.
ing. Film thickness can also be determined by using an aluminum tab
alon
...