ASTM D4933-16

Standard Guide for Moisture Conditioning of Wood and Wood-Based Materials

SIGNIFICANCE AND USE
4.1 Many physical and mechanical properties of wood and wood-based materials change in response to the environmental equilibrium moisture content, and any comparison of these properties must take moisture content into account. A consistent base for comparison among different test samples and different laboratories is necessary. Shrinkage and dimensional change in particular are dependent on moisture content, and tests involving their measurement must be conducted with good equilibrium moisture content control. Conditioning can also be important in industrial settings where there are optimum moisture content levels for many products and processes, and conformance to these levels can reduce losses in quality and yield.
SCOPE
1.1 This guide covers standard procedures for conditioning and equilibrating wood and wood-based materials to constant moisture content. The procedures apply to solid wood, wood-based fiber and particulate materials and panels, and wood products containing adhesives. They are intended for use in research and development activities, testing laboratories, quality control, and for all other classes of producers and users. This guide includes background material on the importance of moisture content control, important definitions and technical data, possible types of apparatus, procedures, and the importance of conditioning time. Users should recognize that the necessary degree of precision and bias varies with the intentions of the users. Some research and testing, for example, might require very close control of moisture content, whereas control in an industrial storage facility might not require such close control. This guide offers procedures that include these different requirements.  
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.3 The following safety hazards caveat pertains only to the procedure section, Section 6, of this guide. 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

• Status: Historical
• Publication Date: 31-Jul-2016
• ICS: 79.060.01 - Wood-based panels in general
• Technical Committee: D07 - Wood
• Drafting Committee: D07.01 - Fundamental Test Methods and Properties

Standards Content (Sample)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: D4933 − 16
Standard Guide for
1
Moisture Conditioning of Wood and Wood-Based Materials
This standard is issued under the fixed designation D4933; 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 D4442Test Methods for Direct Moisture Content Measure-
ment of Wood and Wood-Based Materials
1.1 This guide covers standard procedures for conditioning
E104Practice for Maintaining Constant Relative Humidity
and equilibrating wood and wood-based materials to constant
by Means of Aqueous Solutions
moisture content. The procedures apply to solid wood, wood-
based fiber and particulate materials and panels, and wood 2.2 ISO Standard:
products containing adhesives. They are intended for use in ISO 554Atmospheres for Conditioning and/or Testing—
3
research and development activities, testing laboratories, qual- Specifications
ity control, and for all other classes of producers and users.
This guide includes background material on the importance of 3. Terminology
moisture content control, important definitions and technical
3.1 Definitions:
data, possible types of apparatus, procedures, and the impor-
3.1.1 The following terms are defined in accordance with
tance of conditioning time. Users should recognize that the
Terminology D9.
necessary degree of precision and bias varies with the inten-
3.1.2 equilibrium moisture content—a moisture content at
tions of the users. Some research and testing, for example,
whichwoodneithergainsnorlosesmoisturetothesurrounding
might require very close control of moisture content, whereas
air.
control in an industrial storage facility might not require such
3.1.2.1 Discussion—Equilibrium moisture content (EMC)
close control. This guide offers procedures that include these
generally connotes a moisture content at which a nominal
different requirements.
speciesofsolidwoodwillequilibrate.“Nominal”isusedinthe
1.2 The values stated in SI units are to be regarded as
senseofa“hypotheticalaverage”ratherthananactualspecies.
standard. No other units of measurement are included in this
At constant EMC environmental conditions, however, various
standard.
wood-base materials can reach different levels of EMC. It is
1.3 The following safety hazards caveat pertains only to the more appropriate, therefore, to refer to conditioning at speci-
procedure section, Section 6, of this guide. This standard does fied relative humidity (RH) and temperature conditions than to
a particular EMC. Recommendations for conditioning are
not purport to address all of the safety concerns, if any,
associated with its use. It is the responsibility of the user of this given in ISO 554. Nominal values for equilibrium moisture
content (EMC) are given in Appendix X1. Caution must be
standard to establish appropriate safety and health practices
and determine the applicability of regulatory limitations prior used in calculating or using these values since they represent a
compromise between variation with species, and adsorption
to use.
and desorption. Also, wood containing high levels of extrac-
2. Referenced Documents tives or chemicals may equilibrate at different moisture con-
2
tents. The data in Tables X1.1 and X1.2 were generated from
2.1 ASTM Standards:
the regression equation in X1.1, which is explained in more
D9Terminology Relating to Wood and Wood-Based Prod-
4
detail in Ref (1).
ucts
3.1.3 moisture content—the amount of water contained in
the wood, usually expressed as a percentage of the mass of the
1
This guide is under the jurisdiction ofASTM Committee D07 on Wood and is oven-dry wood.
thedirectresponsibilityofSubcommitteeD07.01onFundamentalTestMethodsand
3.2 Definitions of Terms Specific to This Standard:
Properties.
Current edition approved Aug. 1, 2016. Published September 2016. Originally
approved in 1989. Last previous edition approved in 2010 as D4933–99(2010).
DOI: 10.1520/D4933-16.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available fromAmerican National Standards Institute (ANSI), 25 W. 43rd St.,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM 4th Floor, New York, NY 10036, http://www.ansi.org.
4
Standards volume information, refer to the standard’s Document Summary page on Theboldfacenumbersinparenthesesrefertothelistofreferencesattheendof
the ASTM website. this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4933 − 16
3.2.1 hysteresis—the equilibrium moisture content (EMC) 5.4 Conditioning C
...

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: D4933 − 99 (Reapproved 2010) D4933 − 16
Standard Guide for
1
Moisture Conditioning of Wood and Wood-Based Materials
This standard is issued under the fixed designation D4933; 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 guide covers standard procedures for conditioning and equilibrating wood and wood-based materials to constant
moisture content. The procedures apply to solid wood, wood-based fiber and particulate materials and panels, and wood products
containing adhesives. They are intended for use in research and development activities, testing laboratories, quality control, and
for all other classes of producers and users. This guide includes background material on the importance of moisture content control,
important definitions and technical data, possible types of apparatus, procedures, and the importance of conditioning time. Users
should recognize that the necessary degree of precision and bias varies with the intentions of the users. Some research and testing,
for example, might require very close control of moisture content, whereas control in an industrial storage facility might not require
such close control. This guide offers procedures that include these different requirements.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
1.3 The following safety hazards caveat pertains only to the procedure section, Section 6, of this guide.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.
2. Referenced Documents
2
2.1 ASTM Standards:
D9 Terminology Relating to Wood and Wood-Based Products
D4442 Test Methods for Direct Moisture Content Measurement of Wood and Wood-Based Materials
E104 Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions
2.2 ISO Standard:
3
ISO 554 Atmospheres for Conditioning and/or Testing—Specifications
3. Terminology
3.1 Definitions:
3.1.1 The following terms are defined in accordance with Terminology D9.
3.1.2 equilibrium moisture content—a moisture content at which wood neither gains nor loses moisture to the surrounding air.
1
This guide is under the jurisdiction of ASTM Committee D07 on Wood and is the direct responsibility of Subcommittee D07.01 on Fundamental Test Methods and
Properties.
Current edition approved May 1, 2010Aug. 1, 2016. Published June 2010September 2016. Originally approved in 1989. Last previous edition approved in 20042010 as
D4933 – 99 (2004).(2010). DOI: 10.1520/D4933-99R10.10.1520/D4933-16.
2
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.
3
Available from American National Standards Institute (ANSI), 25 W. 43rd St., 4th Floor, New York, NY 10036, http://www.ansi.org.
3.1.2.1 Discussion—
Equilibrium moisture content (EMC) generally connotes a moisture content at which a nominal species of solid wood will
equilibrate.“ Nominal” is used in the sense of a “hypothetical average” rather than an actual species. At constant EMC
environmental conditions, however, various wood-base materials can reach different levels of EMC. It is more appropriate,
therefore, to refer to conditioning at specified relative humidity (RH) and temperature conditions than to a particular EMC.
Recommendations for conditioning are given in ISO 554. Nominal values for equilibrium moisture content (EMC) are given in
Appendix X1. Caution must be used in calculating or using these values since they represent a compromise between variation with
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

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D4933 − 16
species, and adsorption and desorption. Also, wood containing high levels of extractives or chemicals may equilibrate at different
moisture contents. The data in Tables X1.1 and X1.2 were generated from the regression equation in X1.1,
...