ASTM D8561-24

• Abstract:

  SIGNIFICANCE AND USE; 5.1 Gel time is important in determining batch uniformity and some processing characteristics. It is indicative of pot life and shelf life.; SCOPE; 1.1 This test method covers the determination of the gel time of a solventless varnish mixed with a catalyst, if required, and exposed to elevated temperature. ; 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard. ; Note 1: Although this test method and IEC 60455-2 differ in approach or detail, data obtained using either are technically equivalent. ; 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. For a specific precaution statement, see Section 8. ; 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.

• Status: Published
• Publication Date: 29-Feb-2024
• Technical Committee: D09 - Electrical and Electronic Insulating Materials
• Drafting Committee: D09.01 - Electrical Insulating Products

• Refers: ASTM D1711-24 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Mar-2024
• Refers: ASTM D1711-22 - Standard Terminology Relating to Electrical Insulation
• Effective Date: 01-Sep-2022

Overview

ASTM D8561-24 is the Standard Test Method for Gel Time of Solventless Varnishes by Plunger Method, established by ASTM International. This standard provides a precise procedure for determining the gel time of solventless varnishes, particularly when mixed with a catalyst and exposed to elevated temperatures. Gel time is a critical property of varnishes and resins, signifying the transition from a liquid to a gel state under controlled heat. Assessing gel time plays an essential role in evaluating batch uniformity, processing characteristics, pot life, and shelf life of the varnish.

Key Topics

• Scope: Covers the test method for determining the gel time of solventless varnishes, mixed with a catalyst if necessary, subjected to high temperatures.
• Apparatus:
  • Special plunger apparatus (aluminum wire, helical end, test tube, foam ring)
  • Heating block or bath capable of maintaining stable temperatures up to 200°C
  • Optical sensor, timer, and balance with high precision
• Gel Time Definition: The time, at specified temperature, for a solventless varnish to shift from liquid to gel, as measured with a suitable apparatus.
• Test Procedure:
  • Prepare and mix the solventless varnish with catalyst
  • Insert in a standard test tube with the plunger
  • Place in heated environment and start timer
  • Measure time until gelation is detected via optical sensor
• Reporting:
  • Record varnish identification, amount and type of catalyst, gel time to the nearest 0.1 minute, and test temperature
• Safety Considerations: Emphasizes responsible handling, storage, and ventilation, especially near varnish flashpoint
• International Alignment: Developed in line with WTO TBT Committee principles and acknowledges technical equivalency with IEC 60455-2

Applications

• Batch Control in Manufacturing: The gel time test ensures each batch of solventless varnish meets required specifications for consistency and processing.
• Quality Assurance: Tracking gel time helps maintain product quality and reliability in applications requiring electrical insulation or protective coatings.
• Process Optimization: Provides critical data for optimizing pot life and shelf life, supporting efficient scheduling in industrial environments.
• Material Certification: Data from ASTM D8561-24 testing often supports material certification and technical datasheets for varnish suppliers.
• Safety Validation: Enables users to establish appropriate safety protocols by understanding curing behavior under specified conditions.

Related Standards

• ASTM D1711 - Terminology Relating to Electrical Insulation: Provides key definitions referenced in ASTM D8561-24.
• IEC 60455-2 - Resin Based Reactive Compounds Used for Electrical Insulation - Part 2: Methods of Test: Offers an alternative but technically equivalent approach to gel time determination.
• Other ASTM standards on insulating materials and varnishes may provide complementary testing methods or safety guidelines.

By following ASTM D8561-24, manufacturers, quality controllers, and laboratory technicians can ensure accurate and repeatable measurement of gel time for solventless varnishes, supporting high standards in electrical insulation, protective coatings, and related industries. For further details or access to the full standard, visit the ASTM International website.

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: D8561 − 24
Standard Test Method for
Gel Time of Solventless Varnishes by Plunger Method
This standard is issued under the fixed designation D8561; 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 3.2 Definitions:
3.2.1 gel time, n—of solventless varnish, the time required
1.1 This test method covers the determination of the gel
at a specified temperature for a solventless varnish to be
time of a solventless varnish mixed with a catalyst, if required,
transformed from a liquid state to a gel as measured with a
and exposed to elevated temperature.
suitable gel time apparatus.
1.2 The values stated in SI units are to be regarded as
standard. No other units of measurement are included in this
4. Summary of Test Method
standard.
4.1 A specific size sample of liquid solventless insulating
NOTE 1—Although this test method and IEC 60455-2 differ in approach
varnish is placed in a tube. A plunger is inserted into the
or detail, data obtained using either are technically equivalent.
varnish. The tube is placed in a heated block or bath. The
1.3 This standard does not purport to address all of the
plunger is oscillated up and down until the tube is lifted enough
safety concerns, if any, associated with its use. It is the
to trip an optical sensor. This stops the timing mechanism.
responsibility of the user of this standard to establish appro-
priate safety, health, and environmental practices and deter-
5. Significance and Use
mine the applicability of regulatory limitations prior to use.
5.1 Gel time is important in determining batch uniformity
For a specific precaution statement, see Section 8.
and some processing characteristics. It is indicative of pot life
1.4 This international standard was developed in accor-
and shelf life.
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
6. Apparatus
Development of International Standards, Guides and Recom-
6.1 Gel Time Apparatus Consisting of:
mendations issued by the World Trade Organization Technical
6.1.1 Plunger—Aluminum wire (1.0 mm (0.040 in.)), with a
Barriers to Trade (TBT) Committee.
section at one end wound into a helix of 5 turns with an inside
2. Referenced Documents
diameter of approximately 4 mm (0.16 in.). The overall length
of the wire shall be appropriate to the testing machine and
2.1 ASTM Standards:
allow the helix to be in approximate center of the resin in the
D1711 Terminology Relating to Electrical Insulation
test tube.
2.2 IEC Standard:
6.1.2 Test Tube (16 mm by 160 mm).
IEC 60455-2 Resin Based Reactive Compounds Used for
6.1.3 Heating Block or Heating Bath capable of controlling
Electrical Insulation — Part 2: Methods of Test
the temperature to 6 1.0 °C (1.8 °F) up to 200 °C (392 °F).
The bath shall be filled with silicone oil and have agitation to
3. Terminology
maintain a uniform temperature.
3.1 See Terminology D1711 for definitions of other terms
6.1.4 Mechanism capable of moving the plunger up and
relating to electrical insulation.
down at distance of 10 mm (0.38 in.) at a rate of 15 s per cycle.
6.1.5 Optical Sensor set to detect 6 mm movement of the
1 test tube.
This test method is under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and is the direct responsibility of 6.1.6 Foam Ring (Polyethylene)—6 mm (0.63 in.) ID,
Subcommittee D09.01 on Electrical Insulating Products.
35 mm (1.38 in.) OD to trip optical sensor.
Current edition approved March 1, 2024. Published March 2024. DOI: 10.1520/
6.1.7 Timer capable of measuring in 1 s intervals.
D8561-24.
For referenced ASTM s
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