ASTM E1826-23

Standard Specification for Low Volatile Organic Compound (VOC) Corrosion-Inhibiting Adhesive Primer for Aluminum Alloys to Be Adhesively Bonded in Honeycomb Shelter Panels

ABSTRACT
This specification covers pigmented, sprayable, low volatile organic compound (VOC) corrosion-inhibiting adhesive primers for use on aluminum alloys that are to be adhesively bonded in the fabrication of panels for tactical or relocatable shelters. When applied to a properly prepared surface of aluminum alloy, the primer imparts corrosion resistance and forms a surface suitable for structural bonding and for coating with shelter paint finishes. The physical properties of uncured liquid polymer, cured film on primed surfaces, and bonded specimens shall conform to the prescribed requirements.
SCOPE
1.1 This specification covers pigmented, sprayable, low volatile organic compound (VOC) corrosion-inhibiting adhesive primers for use on aluminum alloys that are to be adhesively bonded in the fabrication of panels for tactical shelters. When applied to a properly prepared surface of aluminum alloy, the primer imparts corrosion resistance and forms a surface suitable for structural bonding and for coating with shelter paint finishes.  
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for information only and are not considered standard.  
1.3 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.  
1.4 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-2023
• ICS: 77.120.10 - Aluminium and aluminium alloys
• Technical Committee: E06 - Performance of Buildings
• Drafting Committee: E06.53 - Materials and Processes for Durable Rigidwall Relocatable Structures

Relations

• Refers: ASTM E874-19 - Standard Practice for Adhesive Bonding of Aluminum Facings to Nonmetallic Honeycomb Core for Shelter Panels
• Effective Date: 01-Jul-2019
• 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 E1749-18 - Standard Terminology Relating to Rigid Wall Relocatable Shelters
• Effective Date: 01-Oct-2018
• Refers: ASTM D3167-10(2017) - Standard Test Method for Floating Roller Peel Resistance of Adhesives
• Effective Date: 01-Nov-2017
• Refers: ASTM E631-15 - Standard Terminology of Building Constructions
• Effective Date: 01-Mar-2015
• Refers: ASTM E631-14 - Standard Terminology of Building Constructions
• Effective Date: 01-Nov-2014
• Refers: ASTM B117-11 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Oct-2011
• Refers: ASTM E874-11 - Standard Practice for Adhesive Bonding of Aluminum Facings to Nonmetallic Honeycomb Core for Shelter Panels
• Effective Date: 01-Sep-2011
• Refers: ASTM E874-10a - Standard Practice for Adhesive Bonding of Aluminum Facings to Nonmetallic Honeycomb Core for Shelter Panels
• Effective Date: 01-Nov-2010
• Refers: ASTM E1749-10 - Standard Terminology Relating to Rigid Wall Relocatable Shelters
• Effective Date: 01-Nov-2010
• Refers: ASTM D3167-10 - Standard Test Method for Floating Roller Peel Resistance of Adhesives
• Effective Date: 01-Oct-2010
• Refers: ASTM E874-10 - Standard Practice for Adhesive Bonding of Aluminum Facings to Nonmetallic Honeycomb Core for Shelter Panels
• Effective Date: 01-Oct-2010
• Refers: ASTM B117-09 - Standard Practice for Operating Salt Spray (Fog) Apparatus
• Effective Date: 01-Jul-2009
• Refers: ASTM E864-08 - Standard Practice for Surface Preparation of Aluminum Alloys to be Adhesively Bonded in Honeycomb Shelter Panels
• Effective Date: 01-Nov-2008
• Refers: ASTM E865-08 - Standard Specification for Structural Film Adhesives for Honeycomb Sandwich Panels
• Effective Date: 01-Nov-2008

Overview

ASTM E1826-23 is the internationally recognized standard specification for low volatile organic compound (VOC), corrosion-inhibiting adhesive primers specifically designed for aluminum alloys used in honeycomb shelter panels. Issued by ASTM International and approved for use by the U.S. Department of Defense, this standard details requirements for pigmented, sprayable adhesive primers that are crucial in the fabrication of tactical or relocatable shelters. The specification establishes stringent criteria for corrosion resistance, bond strength, environmental durability, and VOC content, ensuring both structural integrity and environmental compliance.

Key Topics

• Low VOC Adhesive Primer: The standard emphasizes the importance of minimising volatile organic compounds, setting a maximum VOC content for the primer to ensure workplace safety and regulatory compliance, particularly in aerospace and defense manufacturing.
• Corrosion Resistance: The primer, when correctly applied to aluminum alloy surfaces, must provide robust corrosion protection, extending service life and performance in challenging environments.
• Adhesive Bonding Suitability: Surfaces primed according to ASTM E1826-23 are rendered optimally suitable for strong structural adhesive bonds, vital for honeycomb sandwich panel fabrication.
• Environmental Durability: The specification includes requirements for stability under varying humidity, temperatures, and salt spray, confirming the primer’s performance in severe operational conditions.
• Application and Testing Methods: The document outlines approved methods for primer application, curing, and performance testing (including shear and peel strength), as well as packaging and labelling requirements for quality assurance.

Applications

ASTM E1826-23 is pivotal in a range of demanding construction and manufacturing settings, including:

• Tactical and Relocatable Shelters: Widely used in military and emergency response facilities where honeycomb panel structures must be lightweight, durable, and rapidly deployable.
• Aerospace and Defense: Ensures reliable adhesive bonding and corrosion resistance in aircraft shelters, transportable command centers, and field hospitals that utilize aluminum alloy panels.
• Building Construction: Applied in rigid wall modular or temporary buildings, enhancing longevity and maintenance cycles through engineered corrosion protection and superior bonding properties.

Key benefits of implementing this standard include:

• Enhanced durability and service life of aluminum structures in corrosive environments.
• Improved safety and health profiles due to low VOC content.
• Confidence in meeting both structural and environmental compliance requirements for defense and infrastructure projects.

Related Standards

ASTM E1826-23 references and complements several other industry standards essential to the quality control of aluminum adhesives and panel construction, such as:

• ASTM B117 - Practice for Operating Salt Spray (Fog) Apparatus
• ASTM B209/B209M - Specification for Aluminum and Aluminum-Alloy Sheet and Plate
• ASTM D1002 - Test Method for Apparent Shear Strength of Adhesively Bonded Metal Specimens
• ASTM D3167 - Test Method for Floating Roller Peel Resistance of Adhesives
• ASTM E864 - Practice for Surface Preparation of Aluminum Alloys for Adhesive Bonding
• ASTM E865 & E874 - Specifications for Structural Film Adhesives and Adhesive Bonding of Aluminum Facings
• Federal Specifications QQ-A-250/8d, QQ-A-250/11d - Aluminum alloy plate and sheet
• Rule 1124 - South Coast Air Quality Management District’s regulation for aerospace assembly VOC emissions

Keywords: low VOC adhesive primer, corrosion-inhibiting primer, aluminum alloy bonding, honeycomb shelter panels, ASTM E1826-23, tactical shelters, environmental resistance, structural adhesives, military shelters.

By adhering to ASTM E1826-23, manufacturers and users ensure the reliable performance of aluminum structures in vital shelter applications while meeting rigorous environmental and quality standards.

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: E1826 − 23
Standard Specification for
Low Volatile Organic Compound (VOC) Corrosion-Inhibiting
Adhesive Primer for Aluminum Alloys to Be Adhesively
Bonded in Honeycomb Shelter Panels
This standard is issued under the fixed designation E1826; 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 D1002 Test Method for Apparent Shear Strength of Single-
Lap-Joint Adhesively Bonded Metal Specimens by Ten-
1.1 This specification covers pigmented, sprayable, low
sion Loading (Metal-to-Metal)
volatile organic compound (VOC) corrosion-inhibiting adhe-
D3167 Test Method for Floating Roller Peel Resistance of
sive primers for use on aluminum alloys that are to be
Adhesives
adhesively bonded in the fabrication of panels for tactical
E631 Terminology of Building Constructions
shelters. When applied to a properly prepared surface of
E864 Practice for Surface Preparation of Aluminum Alloys
aluminum alloy, the primer imparts corrosion resistance and
to Be Adhesively Bonded in Honeycomb Shelter Panels
forms a surface suitable for structural bonding and for coating
E865 Specification for Structural Film Adhesives for Hon-
with shelter paint finishes.
eycomb Sandwich Panels
1.2 The values stated in SI units are to be regarded as
E874 Practice for Adhesive Bonding of Aluminum Facings
standard. The values given in parentheses after SI units are
to Nonmetallic Honeycomb Core for Shelter Panels
provided for information only and are not considered standard.
E1749 Terminology Relating to Rigid Wall Relocatable
1.3 This standard does not purport to address all of the Shelters
safety concerns, if any, associated with its use. It is the 3
2.2 Federal Specifications:
responsibility of the user of this standard to establish appro-
QQ-A-250/8d Aluminum Alloy 5052 H34 Plate and Sheet
priate safety, health, and environmental practices and deter-
QQ-A-250/11d Aluminum Alloy 6061 T6 Plate and Sheet
mine the applicability of regulatory limitations prior to use.
2.3 Government Document:
1.4 This international standard was developed in accor-
Rule 1124 Aerospace Assembly and Component Manufac-
dance with internationally recognized principles on standard-
turing Operations, South Coast Air Quality Management
ization established in the Decision on Principles for the
District
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical
3. Terminology
Barriers to Trade (TBT) Committee.
3.1 Definitions—For definitions of general terms related to
2. Referenced Documents
building construction used in this specification, refer to Termi-
nology E631, and for general terms related to rigid wall
2.1 ASTM Standards:
relocatable shelters, refer to Terminology E1749.
B117 Practice for Operating Salt Spray (Fog) Apparatus
B209/B209M Specification for Aluminum and Aluminum-
4. Materials and Manufacturer
Alloy Sheet and Plate
4.1 The primer shall be a pigmented liquid composed of a
modified epoxy phenolic or other resin system compounded to
This specification is under the jurisdiction of ASTM Committee E06 on
be spray-applied to produce a continuous, uniform coating
Performance of Buildings and is the direct responsibility of Subcommittee E06.53
without dilution.
on Materials and Processes for Durable Rigidwall Relocatable Structures.
Current edition approved May 1, 2023. Published June 2023. Originally
approved in 1996. Last previous edition approved in 2020 as E1826 – 20. DOI:
10.1520/E1826-23.
2 3
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Available from DLA Document Services, Building 4/D, 700 Robbins Ave.,
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Philadelphia, PA 19111, http://quicksearch.dla.mil.
Standards volume information, refer to the standard’s Document Summary page on Available from South Coast Air Quality Management District (AQMD), 21865
the ASTM website. Copley Dr., Diamond Bar, CA 91765, http://www.aqmd.gov.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1826 − 23
TABLE 2 Physical Property of Cured Film on Primed Surfaces
5. Physical Properties
Test Requirement
5.1 The uncured primer shall be tested as specified in 6.1
Smooth uniform coating 0.0025 mm to 0.010 mm (0.0001 in. to
and meet the requirement of Table 1.
0.0004 in.) ± 15 % coefficient of variation
5.2 Properties of Cured Film—When applied and cured in
accordance with 6.1.8, the cured film shall meet the require-
TABLE 3 Physical Properties of Bonded Specimens
ments of Tables 2 and 3 when tested as specified in 6.2 and 6.3.
Requirements
Test
5.3 Storage Stability—Primer stored in accordance with
(min)
6.1.3 shall meet the requirements for normal- and low-
Normal-temperature lap shear, 24 °C (77 °F), MPa (psi) 20.0 (2903)
Low-temperature lap shear, −55 °C (−67 °F), MPa (psi) 20.0 (2903)
temperature floating roller peel in Table 3 when cured in
High-temperature lap shear, 93 °C (200 °F), MPa (psi) 13.0 (1890)
accordance with 6.1.8 and tested as specified in 6.3.7 and 6.3.8.
Humidity exposure lap shear, 93 °C (200 °F), MPa (psi) 8.0 (1161)
Salt spray exposure lap shear, 35 °C (95 °F), MPa (psi) 16.0 (2322)
5.4 Shelf Life—The shelf life of the primer at 25 °C 6 7 °C
Normal-temperature floating roller peel strength, 24 °C (75 °F), 4400 (25.1)
(77 °F 6 12 °F) shall be at least four days. After four days,
N/m (lbf/in.)
when tested according to 6.1.4, the primer shall meet the Low-temperature floating roller peel strength, −55 °C (−67 °F), 2625 (15.0)
N/m (lbf/in.)
requirements for normal- and low-temperature floating roller
peel in Table 3 when cured in accordance with 6.1.8 and tested
as specified in 6.3.7 and 6.3.8.
5.5 Film Thickness—The average, minimum, and maximum
6.1.3 Storage Stability—Store a sample of the primer for
film thicknesses shall be between 0.0025 mm and 0.010 mm
three months from the date of manufacture at a temperature
(0.0001 in. and 0.0004 in.) 615 % coefficient of variation. At
recommended by the manufacturer. The stored sample shall
least five thickness readings shall be made with no more than
2 2
meet the requirements for normal- and low-temperature float-
one in any 645 mm (1 in. ) area.
ing roller peel in Table 3 when cured in accordance with 6.1.8
5.6 VOC Content—The volatile organic compound (VOC)
and tested as specified in 6.3.7 and 6.3.8.
is any volatile compound containing the element of carbon,
6.1.4 Shelf Life—Store a sample of the primer for four days
excluding methane, carbon monoxide, carbon dioxide, car-
at 25 °C 6 7 °C (77 °F 6 13 °F). The aged sample shall meet
bonic acid, metallic carbides or carbonates, and ammonium
the requirements for normal- and low-temperature floating
carbonates, as stated in Rule 1124. The VOC content shall meet
roller peel in Table 3 when cured in accordance with 6.1.8 and
the requirement in Table 1 when determined in accordance
tested as specified in 6.3.7 and 6.3.8.
with 6.1.9.
6.1.5 Film Thickness—The cured primer film thickness shall
be determined with a eddy-current instrument as specified in
6. Test Methods
6.2.2.
6.1 Uncured Primer:
6.1.6 Color—During spray application, there shall be a
6.1.1 Solids Content—Determine the solids content by heat-
discernible color change for the primer thickness specified in
ing a 2 g sample of thoroughly mixed primer in an ignition-loss
5.5.
crucible with cover at 121 °C 6 5 °C (250 °F 6 9 °F) for not
6.1.7 Sprayability—The primer shall be capable of being
less than 90 min. Cool the crucible to room temperature in a
readily applied in accordance with the manufacturer’s instruc-
desiccator. Weighings before and after heating shall be accurate
tions to all test panels of either 6061 T6 or 5052 H34 aluminum
to 60.001 g. Calculate the mass of solids remaining as a
alloy (Fed. Spec. QQ-A-250/11d or QQ-A-250/8d,
percentage of the initial sample mass as follows:
respectively, or Specification B209/B209M) and cleaned in
mass of nonvolatile residue accordance with Practice E864 for each of the tests described
Percent solids content 5 × 100 (1)
initial sample mass in 6.1.8 – 6.3.8.
6.1.8 Curing Properties—Test the cured film for the ability
6.1.2 Ash Content—Place the crucibles containing the solids
to meet the requirements listed in Tables 2 and 3. Spray the
content samples in a furnace at 565 °C 6 28 °C (1050 °F 6
primer onto the test panels and air dry at least 20 min at 24 °C
82 °F) for not less than 60 min. Cool the crucible to room
6 5 °C (77 °F 6 9 °F); then heat in air for 65 min 6 5 min at
temperature in a desiccator. Weighings before and after heating
121 °C 6 5 °C (250 °F 6 9 °F).
shall be accurate to 60.001 g. Calculate the ash content
6.1.9 VOC Content—The grams of VOC per litre of primer,
remaining as a percentage of the solids content as follows:
less water and exempt compounds in accordance with Rule
mass of ash residue
1124, shall be determined by the adhesive primer manufacturer
Percent ash content 5 × 100 (2)
mass of nonvolatile residue
in accordance with Rule 1124 and meet the requirement for
VOC content in Table 1.
TABLE 1 Physical Properties of Uncured Liquid Polymer
6.2 Cured Film:
Test Requirement 6.2.1 Test Panels and Panel Preparation—Test panels shall
Solids content,% Report only be either 6061 T6 or 5052 H34 bare aluminum alloy (Fed.
Ash content, % Report only
Spec. QQ-A-250/11d or QQ-A-250/8d, respectively, or Speci-
Color Easily visible film
fication B209/B209M) and cleaned in accordance with Practice
VOC content 250 g/L max
E864.
E1826 − 23
6.2.2 Smooth Uniform Coating—Clean a 30 cm by 30 cm diameter by 44.5 mm (1.75 in.) in width. The durometer of the
(12 in. by 12 in.) panel, spray to a primer thickness as specified roller surface shall be 70 to 80 Shore A.
in 5.5, and cure as specified in 6.1.8. Determine the primer
6.2.8.4 As an alternative to 6.2.8.3, the tape shall be pressed
thickness with a Fisher isoscope MP2-T3.3B (or equivalent)
down by rolling the tape roll along the strip of applied tape
calibrated with standards between 0.0025 mm and 0.010 mm
using a firm hand pressure of approximately 2 kg (4.4 lb).
(0.0001 in. and 0.0004 in.). The primer thickness shall meet the
6.2.8.5 Remove the tape in one abrupt motion perpendicular
requirements in 5.5 and Table 2.
to the panel. No primer shall be removed from the panel, other
6.2.3 Pencil Hardness—Determine the pencil hardness of
than that previously removed during the scribing procedure in
the cured film using the following procedure:
6.2.8.2.
6.2.3.1 Preparation of Pencils—Prepare a set of drawing
6.3 Bonding Property Tests:
pencils ranging in hardness from 6B to 5H by stripping the
6.3.1 Preparation of Test Specimens—Prepare five speci-
wood away from the end approximately 10 mm ( ⁄8 in.) without
mens in accordance with Practice E864 for each of the tests in
damaging the lead. Square the tip of the lead by holding the
Table 3. The lap shear specimens shall be in accordance with
pencil in a vertical position and moving the lead back and forth
Test Method D1002 and the peel specimens in accordance with
over 400 grit or finer abrasive paper. Square the tip of the lead
Test Method D3167. The adherents shall be of either 6061 T6
after each trial.
or 5052 H34 aluminum alloy (Fed. Spec. QQ-A-250/11d or
6.2.3.2 Procedure—Place a test panel with the cured primer
QQ-
...

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: E1826 − 20 E1826 − 23
Standard Specification for
Low Volatile Organic Compound (VOC) Corrosion-Inhibiting
Adhesive Primer for Aluminum Alloys to Be Adhesively
Bonded in Honeycomb Shelter Panels
This standard is issued under the fixed designation E1826; 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
1.1 This specification covers pigmented, sprayable, low volatile organic compound (VOC) corrosion-inhibiting adhesive primers
for use on aluminum alloys that are to be adhesively bonded in the fabrication of panels for tactical shelters. When applied to a
properly prepared surface of aluminum alloy, the primer imparts corrosion resistance and forms a surface suitable for structural
bonding and for coating with shelter paint finishes.
1.2 The values stated in SI units are to be regarded as standard. The values given in parentheses after SI units are provided for
information only and are not considered standard.
1.3 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.
1.4 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.
2. Referenced Documents
2.1 ASTM Standards:
B117 Practice for Operating Salt Spray (Fog) Apparatus
B209B209/B209M Specification for Aluminum and Aluminum-Alloy Sheet and Plate (Metric) B0209_B0209M
D1002 Test Method for Apparent Shear Strength of Single-Lap-Joint Adhesively Bonded Metal Specimens by Tension Loading
(Metal-to-Metal)
D3167 Test Method for Floating Roller Peel Resistance of Adhesives
E631 Terminology of Building Constructions
E864 Practice for Surface Preparation of Aluminum Alloys to Be Adhesively Bonded in Honeycomb Shelter Panels
E865 Specification for Structural Film Adhesives for Honeycomb Sandwich Panels
E874 Practice for Adhesive Bonding of Aluminum Facings to Nonmetallic Honeycomb Core for Shelter Panels
E1749 Terminology Relating to Rigid Wall Relocatable Shelters
This specification is under the jurisdiction of ASTM Committee E06 on Performance of Buildings and is the direct responsibility of Subcommittee E06.53 on Materials
and Processes for Durable Rigidwall Relocatable Structures.
Current edition approved Sept. 1, 2020May 1, 2023. Published October 2020June 2023. Originally approved in 1996. Last previous edition approved in 20122020 as
E1826 – 12.E1826 – 20. DOI: 10.1520/E1826-20.10.1520/E1826-23.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E1826 − 23
2.2 Federal Specifications:
QQ-A-250/8d Aluminum Alloy 5052 H34 Plate and Sheet
QQ-A-250/11d Aluminum Alloy 6061 T6 Plate and Sheet
2.3 Government Document:
Rule 1124 Aerospace Assembly and Component Manufacturing Operations, South Coast Air Quality Management District
3. Terminology
3.1 Definitions—For definitions of general terms related to building construction used in this specification, refer to Terminology
E631, and for general terms related to rigid wall relocatable shelters, refer to Terminology E1749.
4. Materials and Manufacturer
4.1 The primer shall be a pigmented liquid composed of a modified epoxy phenolic or other resin system compounded to be
spray-applied to produce a continuous, uniform coating without dilution.
5. Physical Properties
5.1 The uncured primer shall be tested as specified in 6.1 and meet the requirement of Table 1.
5.2 Properties of Cured Film—When applied and cured in accordance with 6.1.8, the cured film shall meet the requirements of
Tables 2 and 3 when tested as specified in 6.2 and 6.3.
5.3 Storage Stability—Primer stored in accordance with 6.1.3 shall meet the requirements for normal- and low-temperature
floating roller peel in Table 3 when cured in accordance with 6.1.8 and tested as specified in 6.3.7 and 6.3.8.
5.4 Shelf Life—The shelf life of the primer at 25 °C 6 7 °C (77 °F 6 12 °F) shall be at least four days. After four days, when tested
according to 6.1.4, the primer shall meet the requirements for normal- and low-temperature floating roller peel in Table 3 when
cured in accordance with 6.1.8 and tested as specified in 6.3.7 and 6.3.8.
5.5 Film Thickness—The average, minimum, and maximum film thicknesses shall be between 0.0025 mm and 0.010 mm (0.0001
in. and 0.0004 in.) 615 % coefficient of variation. At least five thickness readings shall be made with no more than one in any
2 2
645 mm (1 in. ) area.
5.6 VOC Content—The volatile organic compound (VOC) is any volatile compound containing the element of carbon, excluding
methane, carbon monoxide, carbon dioxide, carbonic acid, metallic carbides or carbonates, and ammonium carbonates, as stated
in Rule 1124. The VOC content shall meet the requirement in Table 1 when determined in accordance with 6.1.9.
6. Test Methods
6.1 Uncured Primer:
6.1.1 Solids Content—Determine the solids content by heating a 2 g sample of thoroughly mixed primer in an ignition-loss
crucible with cover at 121 °C 6 5 °C (250 °F 6 9 °F) for not less than 90 min. Cool the crucible to room temperature in a
desiccator. Weighings before and after heating shall be accurate to 60.001 g. Calculate the mass of solids remaining as a
percentage of the initial sample mass as follows:
TABLE 1 Physical Properties of Uncured Liquid Polymer
Test Requirement
Solids content,% Report only
Ash content, % Report only
Color Easily visible film
VOC content 250 g/L max
Available from DLA Document Services, Building 4/D, 700 Robbins Ave., Philadelphia, PA 19111, http://quicksearch.dla.mil.
Available from South Coast Air Quality Management District (AQMD), 21865 Copley Dr., Diamond Bar, CA 91765, http://www.aqmd.gov.
E1826 − 23
TABLE 2 Physical Property of Cured Film on Primed Surfaces
Test Requirement
Smooth uniform coating 0.0025 mm to 0.010 mm (0.0001 in. to
0.0004 in.) ± 15 % coefficient of variation
TABLE 3 Physical Properties of Bonded Specimens
Requirements
Test
(min)
Normal-temperature lap shear, 24 °C (77 °F), MPa (psi) 20.0 (2903)
Low-temperature lap shear, −55 °C (−67 °F), MPa (psi) 20.0 (2903)
High-temperature lap shear, 93 °C (200 °F), MPa (psi) 13.0 (1890)
Humidity exposure lap shear, 93 °C (200 °F), MPa (psi) 8.0 (1161)
Salt spray exposure lap shear, 35 °C (95 °F), MPa (psi) 16.0 (2322)
Normal-temperature floating roller peel strength, 24 °C (75 °F), 4400 (25.1)
N/m (lbf/in.)
Low-temperature floating roller peel strength, −55 °C (−67 °F), 2625 (15.0)
N/m (lbf/in.)
mass of nonvolatile residue
Percent solids content 5 ×100 (1)
initial sample mass
6.1.2 Ash Content—Place the crucibles containing the solids content samples in a furnace at 565 °C 6 28 °C (1050 °F 6 82 °F)
for not less than 60 min. Cool the crucible to room temperature in a desiccator. Weighings before and after heating shall be accurate
to 60.001 g. Calculate the ash content remaining as a percentage of the solids content as follows:
mass of ash residue
Percent ash content 5 ×100 (2)
mass of nonvolatile residue
6.1.3 Storage Stability—Store a sample of the primer for three months from the date of manufacture at a temperature
recommended by the manufacturer. The stored sample shall meet the requirements for normal- and low-temperature floating roller
peel in Table 3 when cured in accordance with 6.1.8 and tested as specified in 6.3.7 and 6.3.8.
6.1.4 Shelf Life—Store a sample of the primer for four days at 25 °C 6 7 °C (77 °F 6 13 °F). The aged sample shall meet the
requirements for normal- and low-temperature floating roller peel in Table 3 when cured in accordance with 6.1.8 and tested as
specified in 6.3.7 and 6.3.8.
6.1.5 Film Thickness—The cured primer film thickness shall be determined with a eddy-current instrument as specified in 6.2.2.
6.1.6 Color—During spray application, there shall be a discernible color change for the primer thickness specified in 5.5.
6.1.7 Sprayability—The primer shall be capable of being readily applied in accordance with the manufacturer’s instructions to all
test panels of either 6061 T6 or 5052 H34 aluminum alloy (Fed. Spec. QQ-A-250/11d or QQ-A-250/8d, respectively, or
Specification B209B209/B209M) and cleaned in accordance with Practice E864 for each of the tests described in 6.1.8 – 6.3.8.
6.1.8 Curing Properties—Test the cured film for the ability to meet the requirements listed in Tables 2 and 3. Spray the primer
onto the test panels and air dry at least 20 min at 24 °C 6 5 °C (77 °F 6 9 °F); then heat in air for 6565 min 6 5 min at 121 °C
6 5 °C (250 °F 6 9 °F).
6.1.9 VOC Content—The grams of VOC per litre of primer, less water and exempt compounds per in accordance with Rule 1124,
shall be determined by the adhesive primer manufacturer in accordance with Rule 1124 and meet the requirement for VOC content
in Table 1.
6.2 Cured Film:
6.2.1 Test Panels and Panel Preparation—Test panels shall be either 6061 T6 or 5052 H34 bare aluminum alloy (Fed. Spec.
QQ-A-250/11d or QQ-A-250/8d, respectively, or Specification B209B209/B209M) and cleaned in accordance with Practice E864.
6.2.2 Smooth Uniform Coating—Clean a 30 cm by 30 cm (12 in. by 12 in.) panel, spray to a primer thickness as specified in 5.5,
E1826 − 23
and cure as specified in 6.1.8. Determine the primer thickness with a Fisher isoscope MP2-T3.3B (or equivalent) calibrated with
standards between 0.0025 mm and 0.010 mm (0.0001 in. and 0.0004 in.). The primer thickness shall meet the requirements in 5.5
and Table 2.
6.2.3 Pencil Hardness—Determine the pencil hardness of the cured film using the following procedure:
6.2.3.1 Preparation of Pencils—Prepare a set of drawing pencils ranging in hardness from 6B to 5H by stripping the wood away
from the end approximately 10 mm ( ⁄8 in.) without damaging the lead. Square the tip of the lead by holding the pencil in a vertical
position and moving the lead back and forth over 400 grit or finer abrasive paper. Square the tip of the lead after each trial.
6.2.3.2 Procedure—Place a test panel with the cured primer applied in a horizontal position. Push pencils of increasing hardness
at a 45° angle into the coated surface of the panel until one is found that will cut or scratch the coating. Use the number of this
pencil to express the primer hardness.
6.2.4 Environmental Resistance Test—Clean three test panels for each test described in 6.2.5 – 6.2.7 approximately 76 mm by 127
mm (3 in. by 5 in.) in accordance with 6.2.1. Apply the primer and cure in accordance with 5.5 and 6.1.8. The primed panels shall
be subjected to the environments specified in 6.2.5 – 6.2.7 and there shall be no cracking, no blistering, and a minimum pencil
hardness of 4H.
6.2.5 Water Resistance—Immerse the panels with the cured primer coating in distilled water for seven days at 24 °C 6 3 °C (75 °F
6 5 °F
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