ASTM D7842 Holding Strength Testing for Tack & Prong Fastener Buttons
ASTM D7842M-12 explains the measurement of the holding strength of a tack and prong fastener attached button with the help of a tensile testing machine. The buttons are attached to the fabric in the way they are normally used. This test method is applicable to buttons of fabric that are used in apparel. SI units are preferred in stating the values.
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- Overview
- Scope, Applications, and Benefits
- Test Process
- Specifications
- Instrumentation
- Results and Deliverables
Overview
ASTM D7842 / D7842M provides a standard test method for measuring the holding strength of buttons attached to fabric using tack and prong-type fasteners. The test evaluates the force required to detach a button from its substrate under direct tensile pull, providing a quantitative measure of fastener attachment integrity.
This test is used by button manufacturers, apparel quality control teams, and fastener specifiers to verify that button attachments meet minimum holding strength requirements for safety, particularly for children’s garments where button detachment poses a choking hazard.
Scope, Applications, and Benefits
Scope
STM D7842 evaluates:
- Tensile pull-off force for tack and prong button attachments
- Holding strength on various fabric types and constructions
- Compliance with minimum attachment strength requirements
- Comparative performance of different fastener types and application parameters
Applications
- Children’s apparel button safety testing (CPSC/ASTM F963)
- Adult garment button attachment quality control
- Industrial and workwear fastener qualification
- Fastener and button manufacturer product development
- Retail and brand quality assurance programs
Benefits
- Quantifies button attachment strength objectively
- Supports compliance with children’s garment safety regulations
- Identifies inadequate attachment before garments reach consumers
- Enables comparison of fastener types and application settings
- Simple, standardized test adaptable to production QC
Test Process
Specimen Preparation
The button and tack/prong fastener are attached to the specified fabric substrate following the fastener manufacturer's recommended application procedure and settings.
1Fixture Setup
The fabric specimen is secured in the lower jaw of a tensile testing machine; a specialized button gripping fixture is attached to the button.
2Tensile Pull Test
Force is applied at a defined crosshead speed (typically 300 mm/min) pulling the button perpendicular to the fabric plane until the button detaches or the fastener fails.
3Reporting
The peak force at detachment (N) is recorded; failure mode (fastener fracture, fabric damage, fastener pull-through) is documented and compared to minimum holding strength requirements.
4Technical Specifications
| Parameter | Details |
|---|---|
| Test Principle | Tensile pull-off of button fastener from fabric |
| Crosshead Speed | 300 mm/min |
| Minimum Holding Strength | ≥90 N (CPSC children's garment requirement, typical) |
| Applicable Fasteners | Tack and prong button fasteners |
| Failure Modes | Fastener fracture, pull-through, fabric damage |
Instrumentation Used for Testing
- Universal testing machine (UTM) with load cell
- Button gripping fixture (ASTM D7842 specified)
- Fabric clamping jaws
- Ruler and gauge for attachment documentation
- Data acquisition software
Results and Deliverables
- Peak pull-off force (N) per specimen
- Mean, minimum, and standard deviation of holding strength
- Failure mode classification for each specimen
- Compliance determination vs. minimum strength requirement
- Full test report per ASTM D7842
Why Choose Infinita Lab for ASTM D7842 / D7842M?
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Frequently Asked Questions
Buttons that detach from children's garments are a choking hazard for young children. US CPSC and ASTM F963 (toy safety standard) impose minimum button attachment strength requirements of ≥90 N to reduce detachment risk under foreseeable use conditions.
Key factors include fastener type and material, application pressure and tool setting, fabric weight and construction (woven vs. knit), number of prong legs, and fabric thickness. Optimal application settings are critical for consistent holding strength.
No. ASTM D7842 is specifically for tack and prong fastener-attached buttons. Sewn button attachment strength is evaluated by different test methods, typically involving thread pull-out or seam strength testing.
A minimum of 10 specimens per sample is recommended for statistical reliability. For regulatory compliance testing, the minimum holding strength requirement must be met by all specimens tested.
Yes. Tightly woven fabrics generally provide higher holding strength than loosely knit fabrics because the prongs have more material to engage. Very open-weave or stretchy fabrics may require different fastener types to achieve adequate attachment.
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