ASTM D1668/D1668M-97a(2021)

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:D1668/D1668M −97a (Reapproved 2021)
Standard Specification for
Glass Fabrics (Woven and Treated) for Roofing and
Waterproofing
This standard is issued under the fixed designation D1668/D1668M; 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.
This specification replaces Federal Specification HH-C-466.
1. Scope 3. Terminology
1.1 This specification covers finished treated (coated)
3.1 Definitions—For definitions of terms used in this
woven-glass fabrics coated with either asphalt, coal-tar pitch,
specification, refer to Terminology D123 or D1079.
or an organic resin compatible with the roofing, waterproofing,
or other usage as specified by the purchaser.
4. Classification of Fabric Treatments with Generally
Applicable Usage
1.2 The values stated in either SI units or inch-pound units
are to be regarded separately as standard. The values stated in
4.1 Type I, Asphalt Treated—Type I is suitable for use with
each system may not be exact equivalents; therefore, each
all asphalts and asphalt-based compounds.
system shall be used independently of the other. Combining
4.2 Type II, Coal-Tar Pitch Treated—Type II is suitable for
values from the two systems may result in nonconformance
use with all coal-tar pitches and coal-tar pitch-based com-
with the standard.
pounds (Note 1).
1.3 This international standard was developed in accor-
dance with internationally recognized principles on standard- 4.3 Type III, Organic Resin Treated—The purchaser and
ization established in the Decision on Principles for the
supplier shall agree on an organic resin that is compatible with
Development of International Standards, Guides and Recom- or is suitable for, or both, the plying liquid plying materials
mendations issued by the World Trade Organization Technical either specified or to be used. This organic resin shall not be
Barriers to Trade (TBT) Committee. water soluble.
NOTE 1—In some instances the purchaser may specify the use of Type
2. Referenced Documents
I or II for systems using other than coal-tar bitumens or asphalt.
2.1 ASTM Standards:
D123 Terminology Relating to Textiles
5. Materials and Manufacture
D146/D146M Test Methods for Sampling and Testing
5.1 The untreated (greige) scrim (open basket weave) or
Bitumen-Saturated Felts and Woven Fabrics for Roofing
leno (locked weave) fabrics shall conform to the requirements
and Waterproofing
as specified in Table 1.
D579/D579M Specification for Greige Woven Glass Fabrics
D1079 Terminology Relating to Roofing and Waterproofing
5.2 In the process of manufacture, the fibers of the untreated
D3775 Test Method for End (Warp) and Pick (Filling) Count
glass fabric shall be thoroughly and uniformly coated using
of Woven Fabrics
equipment which, in combination, handles the fabric and uses
D3776/D3776M Test Methods for Mass Per Unit Area
a machine speed in a total process that will not injure or distort
(Weight) of Fabric
the weave of the fabric.
5.3 Glass fabric is usually woven in nominal widths of 0.91,
This specification is under the jurisdiction of ASTM Committee D08 on
1.83, and 2.74 m [36, 72, and 108 in.] by the weaving mills.
Roofing and Waterproofing and is the direct responsibility of Subcommittee D08.04
Extra warp (the length of the fabric) threads are included in
on Felts, Fabrics and Bituminous Sheet Materials.
1.83 and 2.74-m [72 and 108-in.] wide fabrics to obtain
Current edition approved July 1, 2021. Published July 2021. Originally approved
ɛ1
incremental fabric roll widths of 0.91 m [36 in.]. These extra
in 1959. Last previous edition approved in 2014 as D1668/D1668M – 97a (2014) .
DOI: 10.1520/D1668_D1668M-97AR21.
warp threads with a slitting space between each set (a set of
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
two) of bunched warp threads create a duplicate or “dupe”
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
selvedge with a “brush” edge created by the cut fill threads
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. instead of the usually wrapped fill threads seen in a smooth
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D1668/D1668M−97a (2021)
TABLE 1 Requirements of Untreated Woven Glass Fabrics Types
B C
Scrim Leno
A
Style
20 by 20 Thread Type 20 by 10 Thread Type 10 by 10 Thread Type
2 2
Average dry mass, g/m [oz ⁄yd ]: 47 [1.4] 47 [1.4] 47 [1.4]
Thread count per 25.4 mm [1 in.]:
D
Warp Threads: 20 ± 2 150 1/0 20 ± 2 150 1/0 20 ± 2 150 1/0
E
Filling Threads: 20 ± 2 150 1/0 10 ± 1 75 1/0 10 ± 1 75 1/0
A
“Style” (that is, 20 by 10) as stated as a caption in Table 1 is a weave count of the threads (yarns) present in both the warp and the fill. “Style” is mentioned here for use
as a quick, generic cross reference to the manufacturer’s own fabric numbers.
B
A scrim-type fabric is an open weave (basket or screen) type pattern.
C
The style called “leno” has the same thread count as the 20 by 10.The change in the weave pattern is due to the doubling of the 150 1/0 warp threads (yarns) to produce
mesh openings double the size of the 20 by 20 weave patern. As a greige goods, it is a very stable (locked) weave which continues after the application of the coating
materials.
D
Warp threads (yarns) run the length of the fabric. The warp thread count is measured across the width of the fabric and is expressed in number of threads per lineal inch
or per lineal millimetre (mm).
E
Fill (woof) are the threads (yarns) that run at right angles (perpendicular) to the warp yarns of the fabric. The fill thread count is measured across the length of the fabric
and is expressed in number of threads per lineal inch or per lineal millimetre (mm).
selvedge.This type of fabric selvedge edge is, and has been, an 7. Workmanship, Finish, and Appearance
acceptable fabric design (pattern) in both the weaving and
7.1 Mesh of Fabric—The fabric mesh shall be open an 85 %
construction industry.
minimum average of the maximum mass of the roll with an
5.4 Brush edge of the “dupe” selvedge is not to be included allowable factor of 610 %. This openness of the fabric weave
in the measurement of the finished roll width. is to permit a positive flow-through of the successive moppings
or applications of the liquid plying materials.
5.5 The purchaser may specify widths of more than or less
than 0.91 m [36 in.]. These widths can be furnished at the 7.2 Finish of the Fabric—The fabric finish shall be uni-
manufacturer’s option. formly free of t
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