ASTM D7433-19

Standard Test Method for Measuring Surface Water Absorption of Overlaid Wood-Based Panels

SIGNIFICANCE AND USE
3.1 Water absorptiveness through the surface of an overlaid panel is a function of various characteristics of the overlay and substrate, including overlay resin content, thickness of the overlay, porosity, and permeability.  
3.2 This test method is useful in comparing the water absorption characteristics of different overlaid panel products. The results from this test method are influenced by both the performance of the overlay system and the panel substrate. Therefore, the results are appropriate for comparison of the relative performance of an overlay system when tested over similar or matched panel substrates.
Note 1: Panel attributes that may influence water absorption include, but are not limited to, panel type, wood species, face veneer thickness and grade, preoverlay surface treatment such as sanding, particle geometry and compaction ratio.
SCOPE
1.1 This test method covers the determination of the quantity of water absorbed in a specified time through the surface of an overlaid wood-based panel. The test method measures the rate of water gain within a controlled surface area of the overlaid panel surface when exposed to standing water. The method was adapted from the principles of Test Method D5795.  
1.2 This test method is applicable to various overlaid wood-based panels including, but not limited to, plywood (such as MDO grades and HDO grades referenced in PS 1–09), oriented strand board, medium density fiberboard, particleboard, and hardboard.  
1.3 This test method does not address sampling procedures, number of replications nor performance criteria since those details vary depending upon the purpose of the testing and the type of product. The method is specific to the panel surface and does not evaluate water absorption or edge swell that may occur along panel edges. The method does not consider the variables related to in-service moisture conditions and therefore does not claim to directly relate to water absorption that may occur in actual panel use situations.  
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.  
1.5 This test method 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 test method 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-Mar-2019
• ICS: 79.060.01 - Wood-based panels in general
• Technical Committee: D07 - Wood
• Drafting Committee: D07.03 - Panel Products

Relations

• Replaces: ASTM D7433-13 - Standard Test Method for Measuring Surface Water Absorption of Overlaid Wood-Based Panels
• Effective Date: 01-Apr-2019
• Refers: ASTM D5795-16(2024) - Standard Test Method for Determination of Liquid Water Absorption of Coated Wood and Wood Based Products Via “Cobb Ring” Apparatus
• Effective Date: 01-Feb-2024
• Refers: ASTM D4442-20 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
• Effective Date: 01-Mar-2020
• Refers: ASTM D4442-16 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
• Effective Date: 15-Nov-2016
• Refers: ASTM D5795-16 - Standard Test Method for Determination of Liquid Water Absorption of Coated Wood and Wood Based Products Via “Cobb Ring” Apparatus
• Effective Date: 15-Jul-2016
• Refers: ASTM D4442-15 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
• Effective Date: 01-Jun-2015
• Refers: ASTM D5795-95(2008) - Standard Test Method for Determination of Liquid Water Absorption of Coated Hardboard and Other Composite Wood Products Via<br> <span class='unicode'>&#x201C;</span>Cobb Ring<span class='unicode'>&#x201D;</span> Apparatus
• Effective Date: 01-Jun-2008
• Refers: ASTM D4442-07 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials
• Effective Date: 15-Nov-2007
• Refers: ASTM D5795-95(2000) - Standard Test Method for Determination of Liquid Water Absorption of Coated Hardboard and Other Composite Wood Products Via "Cobb Ring" Apparatus
• Effective Date: 10-May-2000
• Refers: ASTM D4442-92(1997)e1 - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials
• Effective Date: 10-Mar-1997
• Refers: ASTM D4442-92(2003) - Standard Test Methods for Direct Moisture Content Measurement of Wood and Wood-Base Materials
• Effective Date: 15-Feb-1992

Overview

ASTM D7433-19: Standard Test Method for Measuring Surface Water Absorption of Overlaid Wood-Based Panels provides a reliable procedure to determine the quantity of water absorbed through the surface of wood-based panels with overlays when exposed to standing water for a specified period. This widely referenced ASTM standard is essential for evaluating the surface water resistance of products such as plywood, oriented strand board (OSB), medium density fiberboard (MDF), particleboard, and hardboard with various overlay types.

Water absorption performance is critical for wood-based panels used in environments where moisture exposure can occur. ASTM D7433-19 offers manufacturers, specifiers, and quality assurance professionals a standardized approach to compare different products and overlay systems under controlled laboratory conditions.

Key Topics

• Purpose and Scope: This test method is used to measure the rate and quantity of water absorbed into the surface of overlaid panels by simulating exposure to standing water, focusing solely on the surface and not the edges.
• Procedure: The standard describes the preparation of test specimens, the use of sealants, and the measurement of water absorption using a specified ring apparatus and precise weighing techniques.
• Influencing Attributes: Absorptiveness is affected by overlay resin content, overlay thickness, porosity, permeability, panel type, wood species, veneer characteristics, and surface preparation.
• Applicable Panel Types: Covers a range of overlaid wood-based panels, including but not limited to:
  • Medium and high-density overlay (MDO/HDO) plywood (referenced in PS 1-09)
  • Oriented strand board (OSB)
  • Medium density fiberboard (MDF)
  • Particleboard
  • Hardboard
• Limitations: This test evaluates only surface water absorption, not edge swell or total panel performance under in-service moisture exposure. Factors such as sample selection and in-service conditions are not addressed in this method.

Applications

• Quality Control: manufacturers and quality control professionals use the ASTM D7433-19 method to benchmark the performance of different overlay and substrate combinations, ensuring consistency in product water resistance across production batches.
• Product Development: R&D teams employ this test to assess new overlays or treatments aimed at improving moisture resistance, allowing for effective comparison against existing solutions.
• Specification and Procurement: Architects, engineers, and specifiers reference the results of this test when selecting wood-based panels for construction projects where surface water exposure is a concern, such as in exterior or wet-area applications.
• Third-Party Certification: Testing agencies and certifiers utilize ASTM D7433-19 in certification programs, supporting claims related to water resistance on product labels or literature.

Related Standards

• ASTM D5795: Test Method for Determination of Liquid Water Absorption of Coated Wood and Wood-Based Products via Cobb Ring Apparatus – provides foundational principles adapted in ASTM D7433-19.
• ASTM D4442: Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials – referenced for determining initial moisture content before testing.
• PS 1–09: U.S. Voluntary Product Standard for Structural Plywood – referenced for panel types.
• ISO Standards: Related ISO standards for wood-based panel testing may provide complementary guidance for international projects.

Practical Value

Applying ASTM D7433-19 ensures objective evaluation of overlaid wood-based panel products’ resistance to surface water penetration. By following this standard, industry professionals can:

• Obtain comparative and repeatable results across different products
• Document panel performance for regulatory, quality, or specification purposes
• Enhance end-user confidence by verifying moisture resistance through ASTM methods

In summary, ASTM D7433-19 is a key tool for anyone involved in the production, selection, or assessment of overlaid wood-based panels where water resistance and structural integrity are essential.

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: D7433 − 19
Standard Test Method for
Measuring Surface Water Absorption of Overlaid Wood-
Based Panels
This standard is issued under the fixed designation D7433; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
1.1 This test method covers the determination of the quan-
tityofwaterabsorbedinaspecifiedtimethroughthesurfaceof
2. Referenced Documents
an overlaid wood-based panel. The test method measures the
2.1 ASTM Standards:
rate of water gain within a controlled surface area of the
D5795Test Method for Determination of Liquid Water
overlaid panel surface when exposed to standing water. The
Absorption of Coated Wood and Wood Based Products
method was adapted from the principles of Test Method
Via “Cobb Ring” Apparatus
D5795.
D4442Test Methods for Direct Moisture Content Measure-
1.2 This test method is applicable to various overlaid
ment of Wood and Wood-Based Materials
wood-based panels including, but not limited to, plywood
2.2 Other Standards:
(suchasMDOgradesandHDOgradesreferencedinPS1–09),
PS 1–09U.S. Voluntary Product Standard, Structural Ply-
oriented strand board, medium density fiberboard,
wood
particleboard, and hardboard.
3. Significance and Use
1.3 This test method does not address sampling procedures,
3.1 Water absorptiveness through the surface of an overlaid
number of replications nor performance criteria since those
panel is a function of various characteristics of the overlay and
details vary depending upon the purpose of the testing and the
substrate, including overlay resin content, thickness of the
typeofproduct.Themethodisspecifictothepanelsurfaceand
overlay, porosity, and permeability.
does not evaluate water absorption or edge swell that may
occur along panel edges. The method does not consider the
3.2 This test method is useful in comparing the water
variables related to in-service moisture conditions and there-
absorption characteristics of different overlaid panel products.
fore does not claim to directly relate to water absorption that
The results from this test method are influenced by both the
may occur in actual panel use situations.
performance of the overlay system and the panel substrate.
Therefore, the results are appropriate for comparison of the
1.4 The values stated in SI units are to be regarded as
relative performance of an overlay system when tested over
standard. The values given in parentheses are for information
similar or matched panel substrates.
only.
1.5 This test method does not purport to address all of the NOTE 1—Panel attributes that may influence water absorption include,
butarenotlimitedto,paneltype,woodspecies,faceveneerthicknessand
safety concerns, if any, associated with its use. It is the
grade,preoverlaysurfacetreatmentsuchassanding,particlegeometryand
responsibility of the user of this test method to establish
compaction ratio.
appropriate safety, health, and environmental practices and
determine the applicability of regulatory limitations prior to 4. Test Apparatus and Materials
use.
4.1 Rings, formed by cut sections of metal or plastic pipe
1.6 This international standard was developed in accor- withinsidediameterofapproximately108mm(4.25in.)which
dance with internationally recognized principles on standard-
can be sealed to the overlaid panel with silicone or elastomeric
ization established in the Decision on Principles for the sealant.
Development of International Standards, Guides and Recom-
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
This test method is under the jurisdiction ofASTM Committee D07 on Wood Standards volume information, refer to the standard’s Document Summary page on
and is the direct responsibility of Subcommittee D07.03 on Panel Products. the ASTM website.
Current edition approved April 1, 2019. Published June 2019. Originally Available from National Institute of Standards and Technology (NIST), 100
approved in 2008. Last previous edition approved in 2013 as D7433–13. DOI: Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov/
10.1520/D7433-19. standards
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7433 − 19
4.2 Scale, to measure the depth of water column within 0.5 5.2.3 Measure and record the height of the water column
mm(0.020in.)accuracy.Thecrosssectionofthescaleshallbe after soaking for 24 h, +0.2/-0.0 h. Add water if needed to
as small as practical to minimize interference with the water return the water level to 25.4 mm with a tolerance of +0.5/-0.0
depth. mm (1.00 in., +0.02/-0.00 in.).
5.2.4 Measure and record the height of the water column
NOTE 2—A steel p
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D7433 − 13 D7433 − 19
Standard Test Method for
Measuring Surface Water Absorption of Overlaid Wood-
Based Panels
This standard is issued under the fixed designation D7433; 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
1.1 This test method covers the determination of the quantity of water absorbed in a specified time through the surface of an
overlaid wood-based panel. The test method measures the rate of water gain within a controlled surface area of the overlaid panel
surface when exposed to standing water. The method was adapted from the principles of Test Method D5795.
1.2 This test method is applicable to various overlaid wood-based panels including, but not limited to, plywood (such as MDO
grades and HDO grades referenced in PS 1–09), oriented strand board, medium density fiberboard, particleboard, and hardboard.
1.3 This test method does not address sampling procedures, number of replications nor performance criteria since those details
vary depending upon the purpose of the testing and the type of product. The method is specific to the panel surface and does not
evaluate water absorption or edge swell that may occur along panel edges. The method does not consider the variables related to
in-service moisture conditions and therefore does not claim to directly relate to water absorption that may occur in actual panel
use situations.
1.4 The values stated in SI units are to be regarded as standard. The values given in parentheses are for information only.
1.5 This test method 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 test method to establish appropriate safety safety, health, and healthenvironmental 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.
2. Referenced Documents
2.1 ASTM Standards:
D5795 Test Method for Determination of Liquid Water Absorption of Coated Wood and Wood Based Products Via “Cobb Ring”
Apparatus
D4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
2.2 Other Standards:
PS 1–09 U.S. Voluntary Product Standard, Structural Plywood
3. Significance and Use
3.1 Water absorptiveness through the surface of an overlaid panel is a function of various characteristics of the overlay and
substrate, including overlay resin content, thickness of the overlay, porosity, and permeability.
3.2 This test method is useful in comparing the water absorption characteristics of different overlaid panel products. The results
from this test method are influenced by both the performance of the overlay system and the panel substrate. Therefore, the results
are appropriate for comparison of the relative performance of an overlay system when tested over similar or matched panel
substrates.
This test method is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.03 on Panel Products.
Current edition approved Aug. 1, 2013April 1, 2019. Published September 2013June 2019. Originally approved in 2008. Last previous edition approved in 20082013 as
D7433D7433 – 13.–08. DOI: 10.1520/D7433-13.10.1520/D7433-19.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
Available from National Institute of Standards and Technology (NIST), 100 Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov/standards
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D7433 − 19
NOTE 1—Panel attributes that may influence water absorption include, but are not limited to, panel type, wood species, face veneer thickness and grade,
preoverlay surface treatment such as sanding, particle geometry and compaction ratio.
4. Test Apparatus and Materials
4.1 Rings, formed by cut sections of metal or plastic pipe with inside diameter of approximately 108 mm (4.25 in.) which can
be sealed to the overlaid panel with silicone or elastomeric sealant.
4.2 Scale, to measure the depth of water column within 0.5 mm (0.020 in.) accuracy. The cross section of the scale shall be as
small as practical to minimize interference with the water depth.
NOTE 2—A steel pocket scale with etched graduations at 0.01 in. is suitable.
4.3 MixtureSealant, of equal parts beeswax and rosin, to create a coating for for coating the exterior of the specimen in order
to prevent weight change due to absorption or desorption of moisture from the panel specimen in areas other than the test area.
Other sealants that provide equivalent water repellency are permitted.
...