ASTM D779-16
(Test Method)Standard Test Method for Determining the Water Vapor Resistance of Sheet Materials in Contact with Liquid Water by the Dry Indicator Method
Standard Test Method for Determining the Water Vapor Resistance of Sheet Materials in Contact with Liquid Water by the Dry Indicator Method
SIGNIFICANCE AND USE
5.1 The dry indicator used in this test method is so strongly hygroscopic it will change color in a moderate- to high-humidity atmosphere without contacting liquid water. It will also change when in contact with liquid water.
5.2 This test method is of value for materials that come in contact with water on one face and where it is important to evaluate the length of time for water vapor to pass through the material.
SCOPE
1.1 This test method covers the determination of the time required for water vapor to pass through a sheet membrane in contact with liquid water using the dry-indicator method.
1.2 The method has been used to evaluate water resistive barriers, flexible flashing and other materials used in building construction in order to measure their resistance to water vapor transmission.
1.3 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical conversions to SI units that are provided for information only and are not considered standard.
1.4 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
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NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.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: D779 − 16
Standard Test Method for
Determining the Water Vapor Resistance of Sheet Materials
1
in Contact with Liquid Water by the Dry Indicator Method
This standard is issued under the fixed designation D779; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
1. Scope E631 Terminology of Building Constructions
1.1 This test method covers the determination of the time
3. Terminology
required for water vapor to pass through a sheet membrane in
contact with liquid water using the dry-indicator method.
3.1 Definitions—For definitions of general terms related to
building construction used in this test method, refer to Termi-
1.2 The method has been used to evaluate water resistive
nology E631.
barriers, flexible flashing and other materials used in building
construction in order to measure their resistance to water vapor
4. Summary of Test Method
transmission.
4.1 This test method consists of bringing one side of the test
1.3 The values stated in inch-pound units are to be regarded
specimen in contact with water and finding the time required
as standard. The values given in parentheses are mathematical
for water vapor to pass through the specimen, as indicated by
conversions to SI units that are provided for information only
the development of color in an indicator powder consisting of
and are not considered standard.
a mixture of water-soluble dye, sugar, and starch. The sugar
1.4 This standard does not purport to address all of the
serves the two-fold purpose of masking the color of the
safety concerns, if any, associated with its use. It is the
particles of dye as long as they are dry, and of absorbing the
responsibility of the user of this standard to establish appro-
transudedmoistureandholdingitincloseproximitytothedye.
priate safety and health practices and determine the applica-
The starch increases the stability of the mixture.
bility of regulatory limitations prior to use.
4.2 Fivetestsaremadeoneachsideofthetestspecimenand
2. Referenced Documents reported as two separate averages. If the material being tested
2 is intended to be exposed to water on only one side then five
2.1 ASTM Standards:
tests are to be made on the side specified for water exposure.
D585 Practice for Sampling and Accepting a Single Lot of
Paper, Paperboard, Fiberboard, and Related Product
3
5. Significance and Use
(Withdrawn 2010)
D685 Practice for Conditioning Paper and Paper Products 5.1 The dry indicator used in this test method is so strongly
for Testing
hygroscopic it will change color in a moderate- to high-
E122 Practice for Calculating Sample Size to Estimate,With humidity atmosphere without contacting liquid water. It will
Specified Precision, the Average for a Characteristic of a
also change when in contact with liquid water.
Lot or Process
5.2 This test method is of value for materials that come in
contact with water on one face and where it is important to
evaluate the length of time for water vapor to pass through the
1
This test method is under the jurisdiction of ASTM Committee E06 on
material.
Performance of Buildings and is the direct responsibility of Subcommittee E06.55
on Performance of Building Enclosures.
Current edition approved Feb. 1, 2016. Published March 2016. Originally
6. Interferences
approved in 1944. Last previous edition approved in 2003 as D779-03 which was
withdrawn February 2011 and reinstated in February 2016. DOI: 10.1520/D0779-
6.1 This test method is sometimes not applicable to mate-
16.
rials containing large amounts of water-soluble components.
2
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
Standards volume information, refer to the standard’s Document Summary page on 7. Apparatus
the ASTM website.
3
7.1 Any form of apparatus for applying the test may be used
The last approved version of this historical standard is referenced on
www.astm.org. that fulfills the following conditions:
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D779 − 16
7.1.1 Onesurfaceofthespecimeniswetteduniformlyatthe sugar, which contains starch), pure soluble starch, and methyl
moment the count of time is begun, violet dye (Color Index 680). Pass each ingredient separately
7.1.2 The indicator on the opposite surface is continuously through a No. 100 screen (39.4 mesh/mm), and completely dry
visib
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