ASTM F2468-05(2019)

Standard Classification for Specifying Silicone Adhesives and Sealants for Transportation Applications

SIGNIFICANCE AND USE
4.1 The purpose of this classification system is to provide a method of adequately identifying silicone adhesives and sealants through the use of a line call-out designation.  
4.2 This classification system was designed to permit the addition of property values for future silicone adhesives and sealants.
SCOPE
1.1 This classification covers silicone adhesives and sealants intended for but not limited to sealing and retaining metallic and nonmetallic component assemblies in transportation applications. The materials cure to an elastomeric state by their specified cure system and mechanism.
Note 1: The classification system may serve many of the needs of industries using silicone materials. This classification is subject to revision, as the need requires; therefore, the latest revision should always be used.  
1.2 This classification is intended to be a means of classifying silicone materials. It is not intended for engineering design purposes.  
1.3 It is not the intent of this classification to include pressure-sensitive or hot-melt adhesives.  
1.4 In all cases in which the provisions of this classification system would conflict with the referenced ASTM standard for a particular method, the latter shall take precedence.  
1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.  
1.6 The following safety hazards caveat pertains only to the test methods portion, Section 7, of this classification. 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.7 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: 30-Apr-2019
• ICS: 55.040 - Packaging materials and accessories
• ICS: 71.100.55 - Silicones
• Technical Committee: F03 - Gaskets
• Drafting Committee: F03.30 - Classification

Relations

• Replaces: ASTM F2468-05(2011) - Standard Classification for Specifying Silicone Adhesives and Sealants for Transportation Applications
• Effective Date: 01-May-2019
• Refers: ASTM D1898-68(1989) - Standard Practice for Sampling of Plastics (Withdrawn 1998)
• Effective Date: 29-Sep-2023
• Refers: ASTM D149-20 - Standard Test Method for Dielectric Breakdown Voltage and Dielectric Strength of Solid Electrical Insulating Materials at Commercial Power Frequencies
• Effective Date: 01-Jan-2020
• Refers: ASTM D1002-10(2019) - Standard Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading (Metal-to-Metal)
• Effective Date: 01-Apr-2019
• Refers: ASTM D907-12a - Standard Terminology of Adhesives
• Effective Date: 01-Jul-2012
• Refers: ASTM D907-12 - Standard Terminology of Adhesives
• Effective Date: 01-May-2012
• Refers: ASTM D907-11a - Standard Terminology of Adhesives
• Effective Date: 01-Dec-2011
• Refers: ASTM D4800-94(2011) - Standard Guide for Classifying and Specifying Adhesives
• Effective Date: 01-Dec-2011
• Refers: ASTM D907-11 - Standard Terminology of Adhesives
• Effective Date: 01-Jan-2011
• Refers: ASTM C679-03(2009)e1 - Standard Test Method for Tack-Free Time of Elastomeric Sealants
• Effective Date: 01-Jan-2009
• Refers: ASTM D618-08 - Standard Practice for Conditioning Plastics for Testing
• Effective Date: 01-Nov-2008
• Refers: ASTM D907-08b - Standard Terminology of Adhesives
• Effective Date: 01-Oct-2008
• Refers: ASTM D907-08a - Standard Terminology of Adhesives
• Effective Date: 15-Aug-2008
• Refers: ASTM D792-08 - Standard Test Methods for Density and Specific Gravity (Relative Density) of Plastics by Displacement
• Effective Date: 15-Jun-2008
• Refers: ASTM D907-08 - Standard Terminology of Adhesives
• Effective Date: 01-Mar-2008

Overview

ASTM F2468-05(2019): Standard Classification for Specifying Silicone Adhesives and Sealants for Transportation Applications establishes a comprehensive system to classify silicone adhesives and sealants used in transportation settings. Developed by ASTM International, this standard is designed to support manufacturers, suppliers, and end-users in accurately specifying silicone-based materials by using a structured identification and classification system.

This classification covers silicone adhesives and sealants intended for applications such as sealing and retaining both metallic and nonmetallic component assemblies in various transportation environments. The materials are expected to cure to an elastomeric state according to their defined cure system and mechanism. The standard allows for the integration of additional properties over time, providing flexibility for future advancements.

Key Topics

• Classification System: Employs a ten-digit, line call-out numbering method that details critical material characteristics, such as cure system, cure mechanism, application rate, tack-free time, ultimate elongation, tensile strength, blowout resistance, specific gravity, lap shear bond strength, and silicone volatile content.
• Material Scope: Focuses on silicone adhesives and sealants that are not pressure-sensitive or hot-melt adhesives, ensuring compatibility with the complex requirements of transportation applications.
• Referenced Test Methods: Utilizes existing ASTM International test standards for evaluating essential properties, including tension, elongation, dielectric breakdown, tear strength, density, viscosity, and more.
• Suffix Requirements: Provides for additional suffixes to capture special requirements such as heat resistance, corrosivity, electrical properties, fluid resistance, low temperature performance, tear strength, hardness, color, flame retardancy (e.g., UL 94), viscosity, and other user-defined characteristics.
• Standardization Principles: Developed in alignment with internationally recognized norms set by the World Trade Organization’s Technical Barriers to Trade (TBT) Committee.

Applications

Silicone adhesives and sealants classified under ASTM F2468-05(2019) are utilized in a wide range of transportation-related situations, primarily for:

• Sealing Joints and Retaining Assemblies: Ensuring leak-proof and vibration-resistant seals for both metallic and nonmetallic parts in automobiles, rail vehicles, aerospace, marine, and other transportation sectors.
• Component Assembly: Offering reliable bonding for glass, plastic, rubber, and metal components where elastomeric performance is required after curing.
• High Performance Environments: Meeting the stringent durability, heat resistance, chemical compatibility, and environmental resilience necessary in transportation operations.
• Custom and Future Applications: The classification system is expandable, allowing the specification of additional properties for emerging applications and technology advancements.

Related Standards

• ASTM C679: Tack-Free Time of Elastomeric Sealants
• ASTM D412: Tension Testing of Vulcanized Rubber and Thermoplastic Elastomers
• ASTM D471: Rubber Property-Effect of Liquids
• ASTM D624: Tear Strength of Rubber and Thermoplastic Elastomers
• ASTM D792: Density and Specific Gravity of Plastics
• ASTM D1002: Shear Strength of Adhesively Bonded Metal Specimens
• ASTM D1084: Viscosity of Adhesives
• SAE J369: Flammability of Polymeric Interior Materials-Horizontal Test Method
• UL 94: Flammability Testing

Practical Value

ASTM F2468-05(2019) provides essential value to the transportation industry by:

• Ensuring that silicone adhesives and sealants are specified with precise, performance-based criteria.
• Streamlining material selection for product designers, engineers, and manufacturers.
• Facilitating communication across the supply chain through a clear, numeric classification for complex material attributes.
• Supporting regulatory compliance and consistent quality in transportation assemblies involving silicone adhesives and sealants.

By using this standardized classification, stakeholders can enhance product reliability, safety, and interoperability in a range of demanding transportation applications.

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:F2468 −05 (Reapproved 2019)
Standard Classification for
Specifying Silicone Adhesives and Sealants for
Transportation Applications
This standard is issued under the fixed designation F2468; 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 2. Referenced Documents
2.1 ASTM Standards:
1.1 This classification covers silicone adhesives and seal-
C679 Test Method for Tack-Free Time of Elastomeric Seal-
ants intended for but not limited to sealing and retaining
ants
metallic and nonmetallic component assemblies in transporta-
D149 Test Method for Dielectric Breakdown Voltage and
tion applications. The materials cure to an elastomeric state by
DielectricStrengthofSolidElectricalInsulatingMaterials
their specified cure system and mechanism.
at Commercial Power Frequencies
NOTE 1—The classification system may serve many of the needs of
D150 Test Methods forAC Loss Characteristics and Permit-
industries using silicone materials. This classification is subject to
tivity (Dielectric Constant) of Solid Electrical Insulation
revision, as the need requires; therefore, the latest revision should always
D257 Test Methods for DC Resistance or Conductance of
be used.
Insulating Materials
1.2 This classification is intended to be a means of classi-
D412 Test Methods forVulcanized Rubber andThermoplas-
fying silicone materials. It is not intended for engineering
tic Elastomers—Tension
design purposes.
D471 Test Method for Rubber Property—Effect of Liquids
1.3 It is not the intent of this classification to include
D573 Test Method for Rubber—Deterioration in an Air
pressure-sensitive or hot-melt adhesives.
Oven
D618 Practice for Conditioning Plastics for Testing
1.4 In all cases in which the provisions of this classification
D624 Test Method for Tear Strength of Conventional Vul-
system would conflict with the referenced ASTM standard for
canized Rubber and Thermoplastic Elastomers
a particular method, the latter shall take precedence.
D792 Test Methods for Density and Specific Gravity (Rela-
1.5 The values stated in SI units are to be regarded as
tive Density) of Plastics by Displacement
standard. No other units of measurement are included in this
D907 Terminology of Adhesives
standard.
D1002 Test Method for Apparent Shear Strength of Single-
1.6 The following safety hazards caveat pertains only to the Lap-Joint Adhesively Bonded Metal Specimens by Ten-
test methods portion, Section 7, of this classification. This sion Loading (Metal-to-Metal)
standard does not purport to address all of the safety concerns, D1053 Test Methods for Rubber Property—Stiffening at
if any, associated with its use. It is the responsibility of the user LowTemperatures: Flexible Polymers and Coated Fabrics
of this standard to establish appropriate safety, health, and D1084 Test Methods for Viscosity of Adhesives
environmental practices and determine the applicability of D1349 Practice for Rubber—Standard Conditions for Test-
regulatory limitations prior to use. ing
D1415 Test Method for Rubber Property—International
1.7 This international standard was developed in accor-
dance with internationally recognized principles on standard- Hardness
D1566 Terminology Relating to Rubber
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom- D1898 Practice for Sampling of Plastics (Withdrawn 1998)
D2240 Test Method for Rubber Property—Durometer Hard-
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. ness
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
This classification is under the jurisdiction of ASTM Committee F03 on contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
Gaskets and is the direct responsibility of Subcommittee F03.30 on Classification. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved May 1, 2019. Published June 2019. Originally the ASTM website.
approved in 2005. Last previous edition approved in 2011 as F2468 – 05 (2011). The last approved version of this historical standard is referenced on
DOI: 10.1520/F2468-05R19. www.astm.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F2468−05 (2019)
TABLE 1 Minimum Classification Requirements
Selection Property Designation
Order
Sequence
1 23456 7 8 9
st
1 Digit Cure system Addition Acetoxy Alkoxy Amine Enoxy Oxime Free . As
(Cure by-product) (no by- (acetic (methanol, (cyclo- (acetone) (methyl ethyl radical specified
product) acid) ethanol) hexylamine) ketoxime)
nd
2 Digit Cure mechanism One-part Two-part One-part One-part One-part Two-part Radiation . As
moisture moisture radiation radiation- thermal thermal specified
A
cure cure cure moisture cure cure
cure
rd
3 Digit Application rate, g/min <50 50-99 100-199 200-299 300-499 500-749 750-999 >999 As
specified
th
4 Digit Test Method C679, <5 5-9.9 10-19.9 20-29.9 30-39.9 40-49.9 50-60 >60 As
Tack free time, min specified
th
5 Digit Test Methods D412 (Die <100 100-199 200-299 300-499 500-699 700-999 >999 . As
C) specified
Ultimate elongation, %
th
6 Digit Test Methods D412, <0.345 0.345-0.690 0.691-1.035 1.036-1.380 1.381-3.450 3.451-6.899 6.90-14.0 >14 As
Tensile strength, MPa specified
th B
7 Digit Blowout resistance, s <10 10-20 21-30 31-40 41-50 51-60 >60 . As
specified
th
8 Digit Test Methods D792, <0.85 0.86-0.95 0.96-1.05 1.06-1.15 1.16-1.25 1.26-1.35 1.36-1.50 >1.5 As
Specific gravity, g/cc specified
th C
9 Digit Test Method D1002, <0.345 0.345-0.690 0.691-1.035 1.036-1.380 1.381-3.450 3.451-6.899 6.90-14.0 >14 As
Lap shear bond
specified
strength, MPa
th
10 Digit Silicone volatile <0.6 0.6-1.0 1.1-1.9 2.0-2.9 3.0-4.9 5.0-6.9 7-10 >10 As
Content, % specified
A
Ultraviolet light (UV), microwave, or visible light cure.
B
Resistance to blowout refers to the time to failure at a standardized internal pressure using a fixture as agreed upon between producer and user.
C
Standard test conditions: 5 cm (1.97 in.)/min cross head speed, 1 mm (0.039 in.) gap, 1.27 cm (0.50 in.) overlap, Q panel 20204T3 Aluminum (as received).
D3182 PracticeforRubber—Materials,Equipment,andPro- process is complete. When fully cured it forms a barrier to
cedures for Mixing Standard Compounds and Preparing media migration across the joint.
Standard Vulcanized Sheets
3.2.5 sag resistance—a property of some adhesives and
D4800 Guide for Classifying and Specifying Adhesives
sealants that enables the applied or extruded material to retain
2.2 SAE Standard:
its shape before curing or cross-linking.
SAE J369 Flammability of Polymeric Interior Materials—
3.2.6 thixotropic—a rheological property of uncured seal-
Horizontal Test Method
ants in which the sealant resists sagging or slumping unless
2.3 UL Standard:
disturbed by an external force or pressure.
UL 94 Flammability
3.2.7 transportation—any transportation venue involving
land, sea, or air, civilian or military, stationary and small
3. Terminology
engines.
3.1 Definitions—Some terms in this classification are de-
3.2.8 volatiles—low molecular weight components of an
fined in Terminiologies D907 and D1566.
adhesive or sealant that can be extracted by the environment of
3.2 Definitions of Terms Specific to This Standard:
the application.
3.2.1 cure mechanism—the method of initiating the cure for
a silicone material. 4. Significance and Use
3.2.2 cure system—thecross-linkingmechanismthesilicone
4.1 The purpose of this classification system is to provide a
material uses to transition to the elastomeric state.
method of adequately identifying silicone adhesives and seal-
ants through the use of a line call-out designation.
3.2.3 draw-down—a method of sample preparation of vis-
cous and sag-resistant sealants, in which the sealant is leveled
4.2 This classification system was designed to permit the
using a knife or tool to a specified thickness.
addition of property values for future silicone adhesives and
sealants.
3.2.4 formed in place gasket, fipg—a one- or two-
component adhesive or sealant applied wet, uncured, to a joint
5. Classification
surface where the mating parts are assembled before the curing
5.1 A ten-digit numbering system is used to classify a
silicone adhesive and sealant cure system, cure mechanism,
Available from SAE International (SAE), 400 Commonwealth Dr.,Warrendale,
application rate, tack free time; ultimate elongation, tensile
PA 15096-0001, http://www.sae.org.
strength; blowout resistance, lap shear bond strength, specific
Available from Underwriters Laboratories (UL), 333 Pfingsten Rd.,
Northbrook, IL 60062-2096, http://www.ul.com. gravity, and silicone volatile content as defined in Table 1. The
F2468−05 (2019)
TABLE2 Continued
firstcolumn(leftsideofthetable)indicatesthedigitnumberor
order sequence required while the designation numbers for Symbol Characteristic
eachpropertyareindicatedonthetopofthetable.Theten-digit
Second letter
classification number must also be separated with hyphens
A = Copper
between the fourth and fifth digit, and the sixth and seventh
B=Steel
digit as seen in Example 1 (5.1.1). C = Aluminum
Three-digit number
5.1.1 Example 1—To specify a silicone adhesive or sealant
001=0=testmethodtobe specified by user.
with an acetoxy cure system, two-part moisture cure
1 = no permanent discoloration of the metals that does not buff off
mechanism, application rate of 150 g/min, tack free time of 8 with a nonabrasive cloth.
D ELECTRICAL (dielectric/resistance properties)
min, 400 % ultimate elongation, 1.2 MPa tensile strength, 15 s
Second letter
blowout resistance, 1.1 specific gravity, 2.0 MPa lap shear
A = dielectric strength (short time), Test Method D149
bond strength, and 2.5 % silicone volatile, the line call-out Three-digit number x factor of 0.1 = kV ⁄mm, min
B = dielectric strength (step by step), Test Method D149
would be:
Three-digit number x factor of 0.1 = kV ⁄mm, min
C = insulation resistance, Test Methods D257
ASTM F2468, 2232 2 44 2 2454
Three-digit number x factor of 10 =Ω,min
D = dielectric constant at 1 MHz, Test Methods D150, max
where:
Three-digit number x factor of 0.1 = value
2 = the acetoxy cure system,
E = dissipation factor at 1 MHz, Test Methods D150, max
2 = the two-part moisture cure,
Three-digit number x factor of 0.0001 = value
E FLUID RESISTANCE—Test Method D471
3 = application rate between 100 and 199 g/min,
Second letter
2 = tack free time between 5 and 9.9 min,
A = ASTM #1 Oil
4 = ultimate elongation between 300 and 499 %,
B = IRM 902 Oil
4 = tensile strength between 1.036 and 1.380 MPa,
C = IRM 903 Oil
D = ASTM SF105
2 = blowout resistance between 10 and 20 s,
E = ASTM B Fuel
4 = specific grav
...