ASTM D4391-18a

Standard Terminology Relating to The Burning Behavior of Textiles

General Information

• Status: Published
• Publication Date: 30-Jun-2018
• ICS: 13.220.40 - Ignitability and burning behaviour of materials and products
• ICS: 59.080.30 - Textile fabrics
• Technical Committee: D13 - Textiles
• Drafting Committee: D13.92 - Terminology

Overview

ASTM D4391-18a: Standard Terminology Relating to the Burning Behavior of Textiles provides a comprehensive set of standardized definitions for terms used when describing and evaluating the flammability and burning characteristics of textile materials. Developed by ASTM International Committee D13 on Textiles, this terminology standard supports consistency in communication, testing, research, and regulation of textile flammability.

By defining key technical terms, ASTM D4391-18a ensures that manufacturers, testing laboratories, regulatory bodies, and other stakeholders use a common language when discussing topics such as flame resistance, burning behavior, and fire safety in textile products. As textile fire safety remains a priority in a wide range of industries, understanding and applying these standardized terms is essential for compliance, quality control, and product development.

Key Topics

ASTM D4391-18a covers essential terminology including:

• Afterflame – Persistent flaming after the ignition source is removed.
• Afterglow – Continued glowing of a material after flames are extinguished.
• Base burn – Ignition and consumption of the ground (base) fabric in raised surface textile products.
• Burning behavior – All changes in textiles under exposure to heat or flame.
• Combustible textile vs. Flammable textile – Definitions distinguishing between textiles that will ignite and burn and those that sustain a visible flame.
• Flame resistance – The capacity of textiles to inhibit, prevent, or terminate burning upon exposure to an ignition source.
• Flame retardant – Chemicals or treatments applied to textiles to impart flame resistance.
• Heat durability and heat resistance – Retention of material properties after exposure to high temperature.
• Ignition, charring, smoldering, melting, dripping – Stages and behaviors observed during textile combustion.
• Surface flash – Burning restricted to surface fibers without base fabric involvement.
• Flame spread and flame spread time – Movement and timing of flame propagation across textiles.

These terms form the foundation for standardized textile flammability testing, evaluation, and reporting.

Applications

The terminology in ASTM D4391-18a is critical for:

• Textile Flammability Testing: Laboratories rely on these definitions during product testing for flame resistance, ignition, and combustion characteristics.
• Product Safety Compliance: Manufacturers use these terms to ensure textile products meet flammability standards for clothing, upholstery, tents, and other fabric-based items.
• Regulatory Communication: Consistent terminology supports compliance with regulations such as the Flammable Fabrics Act and other safety standards.
• Quality Assurance and R&D: Designers and engineers apply these terms when developing new flame resistant or flame retardant textiles and assessing product safety.
• Training and Standardization: Clear definitions are valuable for educating staff, standardizing test reports, and aligning with international best practices.

Related Standards

ASTM D4391-18a complements and references several important standards and literature, including:

• ASTM D123 – Terminology Relating to Textiles: The source of many base textile definitions.
• ASTM E176 – Terminology Relating to Fire Standards: Broader fire safety and burning behavior definitions.
• ASTM D4108 – Test Method for Thermal Protective Performance by Open Flame Method: Related testing methodologies for clothing materials.
• ISO/DIS 4880/1 and 4880/2 – International draft standards on burning behavior vocabulary.
• Key regulatory frameworks such as the Flammable Fabrics Act (15 USC 1191) and 16 CFR Part 1610.

By adhering to ASTM D4391-18a, organizations ensure their operations, test methods, and documents are aligned with industry consensus and regulatory requirements on burning behavior and flammability of textiles.

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Keywords: ASTM D4391-18a, textile flammability, burning behavior, flame resistance, burning behavior terminology, flammability standards, textile safety, ASTM standards, flame retardant, textile testing

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: D4391 − 18a
Standard Terminology Relating to
The Burning Behavior of Textiles
This standard is issued under the fixed designation D4391; 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.
The definitions in this standard have been approved by the Society and are included in D123 “Terminology Relating to Textiles”. They
are published as a separate collection for the convenience of persons interested in the burning behavior of textiles. A bibliography of
related literature is given in Appendix X1.
afterflame, n—persistent flaming of a material after the igni- subjected to external sources of ignition. (Compare flam-
tion source has been removed. [D13.92] D4391 mable textile, noncombustible textile.)
after-flame time, n—the length of time for which a material
combustion, n—a chemical process of oxidation that occurs at
continues to flame after the ignition source has been
a rate fast enough to produce heat and usually light either as
removed. [D13.92] D4391
glow or flames.
DISCUSSION—Some oxidation such as that of hydrogen emits radia-
afterglow, n—glow in material after the removal of an external
tion outside the visible spectrum.
ignition source or after the cessation (natural or induced) of
flaming of the material. (See also flame, glow, and smol- critical sewn seams, n—in assembly of flame resistant textiles,
those sewn junctions where failure would result in immedi-
dering.)
ate danger or injury.
afterglow time, n—the time afterglow continues after the
cessation of flaming or after removal of the ignition source. dangerously flammable textile, n— not defined. This term is
[D13.92] D4391
implied in the Standard for the Flammability of Clothing
Textiles (16 CFR Part 1610) under the Flammable Fabrics
base burn, n—the point at which the flame burns the ground
Act (15 USC 1191, et seq.) from which a meaning can be
(base) fabric of a raised surface textile fabric and provides a
inferred. (See also flammable textile.)
self-sustaining flame.
DISCUSSION—Base burn is also known as base fabric ignition or
dripping, n—as related to the burning of a textile, liquefied
fusing.The base burns used to establish a Class 3 fabric are those burns
material that separates and falls from a textile.
resulting from surface flash that occur on specimens in places other
DISCUSSION—The liquefied material can demonstrate continued
than the point of impingement when the warp and fill yarns of a raised
melting, burning, flaming, or smoldering as it separates and falls from
surface textile fabric undergo combustion. Base burns can be identified
the textile. This can be significant relative to the performance charac-
by an opacity change, scorching on the reverse side of the fabric, or
teristics of the textile.
when a physical hole is evident.
embrittlement, n—the formation of a brittle residue as the
burn time, n—the time elapsed from ignition until the stop
result of pyrolysis or incomplete combustion.
thread is severed as measured by the timing mechanism of
the test apparatus.
exposure energy to thermal end point, n—thethermalenergy
transferred through a specimen that is sufficient to cause
burning behavior, n—all the changes that take place when
ignition of contiguous materials. [D13.92] D7140
materials or products are exposed to a specified ignition
source.
fire, n—as related to textile flammability, an uncontrolled
conflagration in which materials are destroyed by burning as
charring, n—the formation of carbonaceous residue as the
evidenced by flames of varying size and shape, and a high
result of pyrolysis or incomplete combustion.
intensity heat source of 5 kw or greater, such as a burning
combustible textile, n—a textile that will ignite and burn or
waste basket, grease-fire on a stove, burning building or
that will give off vapors that will ignite and burn when
forest fire.
flame, n—as related to textile flammability, a hot luminous
ThisterminologyisunderthejurisdictionofASTMCommitteeD13onTextiles
zone of gas or matter in gaseous suspension, or both, that is
and is the direct responsibility of Subcommittee D13.92 on Terminology.
undergoing combustion, that is relatively constant in size
Current edition approved July 1, 2018. Published August 2018. Originally
and shape, and that produces a relatively low heat flux.
approved in 1984. Last previous edition approved in 2018 as D4391 – 18. DOI:
10.1520/D4391-18A. (Compare fire.)
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4391 − 18a
DISCUSSION—Examples are a match flame, candle flame, or a Bunsen interdependent. Aspects of glow not involving combustion are defined
burner gas flame. in dictionaries of general terms.
flame application time, n—the time for which the ignition heat durability, n—the extent to which a material retains its
flame is applied to a material. useful properties at ambient air conditions, following its
exposure to a specified temperature and environment for a
flame resistance, n—the property of a material whereby
specified time and its return to the ambient air conditions.
flaming combustion is prevented, terminated, or inhibited
(Compare heat resistance.)
following application of a flaming or nonflaming source of
ignition, with or without subsequent removal of the ignition
heat durable, adj—having heat durability.
source.
heat flux, n—the thermal intensity indicated by the amount of
DISCUSSION—Flame resistance can be an inherent property of the
power per unit area.
basic material or product, or it may be imparted by specific treatment.
DISCUSSION—The SI unit for heat flux is watts per square meter
The degree of flame resistance exhibited by a specific material during
(W/m ).
testing may vary with different test conditions.
heat resistance, n—the extent to which a material retains
flame resistant, adj—indicating characteristics that can en-
useful properties as measured during exposure of the mate-
hance inhibition of a textile to flaming.
rial to a specified temperature and environment for a
DISCUSSION—“Flame resistant” is the government mandated descrip-
tion
...

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: D4391 − 18 D4391 − 18a
Standard Terminology Relating to
The Burning Behavior of Textiles
This standard is issued under the fixed designation D4391; 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.
The definitions in this standard have been approved by the Society and are included in D123 “Terminology Relating to Textiles”. They
are published as a separate collection for the convenience of persons interested in the burning behavior of textiles. A bibliography of
related literature is given in Appendix X1.
afterflame, n—persistent flaming of a material after the ignition source has been removed. [D13.92] D4391
after-flame time, n—the length of time for which a material continues to flame after the ignition source has been removed.
[D13.92] D4391
afterglow, n—glow in material after the removal of an external ignition source or after the cessation (natural or induced) of flaming
of the material. (See also flame, glow, and smoldering.)
afterglow time, n—the time afterglow continues after the cessation of flaming or after removal of the ignition source. [D13.92]
D4391
base burn, n—the point at which the flame burns the ground (base) fabric of a raised surface textile fabric and provides a
self-sustaining flame.
DISCUSSION—
Base burn is also known as base fabric ignition or fusing. The base burns used to establish a Class 3 fabric are those burns resulting from surface flash
that occur on specimens in places other than the point of impingement when the warp and fill yarns of a raised surface textile fabric undergo
combustion. Base burns can be identified by an opacity change, scorching on the reverse side of the fabric, or when a physical hole is evident.
burn time, n—the time elapsed from ignition until the stop thread is severed as measured by the timing mechnsim of the test
apparatus.
burning behavior, n—all the changes that take place when materials or products are exposed to a specified ignition source.
charring, n—the formation of carbonaceous residue as the result of pyrolysis or incomplete combustion.
combustible textile, n—a textile that will ignite and burn or that will give off vapors that will ignite and burn when subjected to
external sources of ignition. (Compare flammable textile, noncombustible textile.)
combustion, n—a chemical process of oxidation that occurs at a rate fast enough to produce heat and usually light either as glow
or flames.
DISCUSSION—
Some oxidation such as that of hydrogen emits radiation outside the visible spectrum.
critical sewn seams, n—in assembly of flame resistant textiles, those sewn junctions where failure would result in immediate
danger or injury.
dangerously flammable textile, n— not defined. This term is implied in the Standard for the Flammability of Clothing Textiles
(16 CFR Part 1610) under the Flammable Fabrics Act (15 USC 1191, et seq.) from which a meaning can be inferred. (See also
flammable textile.)
This terminology is under the jurisdiction of ASTM Committee D13 on Textiles and is the direct responsibility of Subcommittee D13.92 on Terminology.
Current edition approved May 1, 2018July 1, 2018. Published May 2018August 2018. Originally approved in 1984. Last previous edition approved in 20162018 as
ε1
D4391 – 16D4391 – 18. . DOI: 10.1520/D4391-18.10.1520/D4391-18A.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D4391 − 18a
dripping, n—as related to the burning of a textile, liquefied material that separates and falls from a textile.
DISCUSSION—
The liquefied material can demonstrate continued melting, burning, flaming, or smoldering as it separates and falls from the textile. This can be
significant relative to the performance characteristics of the textile.
embrittlement, n—the formation of a brittle residue as the result of pyrolysis or incomplete combustion.
exposure energy to thermal end point, n—the thermal energy transferred through a specimen that is sufficient to cause ignition
of contiguous materials. [D13.92] D7140
fire, n—as related to textile flammability, an uncontrolled conflagration in which materials are destroyed by burning as evidenced
by flames of varying size and shape, and a high intensity heat source of 5 kw or greater, such as a burning waste basket,
grease-fire on a stove, burning building or forest fire.
flame, n—as related to textile flammability, a hot luminous zone of gas or matter in gaseous suspension, or both, that is undergoing
combustion, that is relatively constant in size and shape, and that produces a relatively low heat flux. (Compare fire.)
DISCUSSION—
Examples are a match flame, candle flame, or a Bunsen burner gas flame.
flame application time, n—the time for which the ignition flame is applied to a material.
flame resistance, n—the property of a material whereby flaming combustion is prevented, terminated, or inhibited following
application of a flaming or nonflaming source of ignition, with or without subsequent removal of the ignition source.
DISCUSSION—
Flame resistance can be an inherent property of the basic material or product, or it may be imparted by specific treatment. The degree of flame resistance
exhibited by a specific material during testing may vary with different test conditions.
flame resistant, adj—indicating characteristics that can enhance inhibition of a textile to flaming.
DISCUSSION—
“Flame resistant” is the government mandated description for certain products that meet established governmental conformance standards or
specifications when the product is tested by a specific method. Where no conformance standards exist, “flame resistant” is a relative term and is used
to compare one material to another.
flame retardant, adj—not defined. This term should not be used as an adjective except in the terms “flame-retardant-treated” and
“flame-retardant treatment”.
flame retardant, n—a chemical used to impart flame resistance.
flame-retardant-treated, adj—having received a flame-retardant treatment.
DISCUSSION—
The term “flame-retardant-treated” does not apply to textiles that are inherently-flame-resistant due to the intrinsic
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