Seam strength & slippage

Introduction

Seam slippage is a critical performance property of woven textile fabrics. It occurs when yarns adjacent to a sewn seam are displaced under applied force, causing the seam to open and affecting the appearance, durability, and functionality of the garment.

Seam slippage testing helps manufacturers evaluate the ability of fabrics to withstand stresses encountered during wear and use. International standards such as ISO 13936-1 and ISO 13936-2 are widely used to assess seam performance.

Professional laboratories such as METS Laboratories perform seam slippage testing to help manufacturers meet quality requirements, retailer specifications, and international standards.

Seam Slippage Testing Laboratory

What is Seam Slippage?

Seam slippage is the movement of yarns away from a sewn seam when subjected to tensile force.

The test evaluates:

1. Resistance of yarns to displacement
2. Seam opening under load
3. Fabric suitability for garment construction
4. Performance of woven fabrics during use

Seam slippage is particularly important for:

1. Apparel fabrics
2. Lightweight woven fabrics
3. Uniforms
4. Home textiles
5. Upholstery fabrics
6. Fashion garments 

Importance of Seam Slippage Testing

Seam slippage testing helps manufacturers:

1. Improve garment durability
2. Prevent seam failure complaints
3. Evaluate fabric construction quality
4. Meet retailer requirements
5. Support product development
6. Ensure customer satisfaction

Many buyers specify maximum allowable seam opening values before approving fabrics.

Test Principle

A fabric specimen containing a standard sewn seam is mounted in a tensile testing machine.

A controlled tensile force is applied perpendicular to the seam direction.

The test measures either:

1. The force required to achieve a specified seam opening, or
2. The seam opening resulting from a specified force.

Test Equipment

The test typically uses:

1. Universal tensile testing machine
2. Standard sewing equipment
3. Calibrated measurement devices
4. Specialized specimen clamps

Test Procedure

Sample Preparation

1. Fabric specimens are cut according to the standard.
2. A standardized seam is sewn in the specimen.
3. Samples are conditioned under standard laboratory conditions.

Tensile Loading

The specimen is mounted in the tensile tester.

The machine applies force at a controlled rate until:

1. A specified seam opening is reached, or
2. A specified force is applied.

Measurement

Laboratory specialists record:

1. Seam opening (mm)
2. Applied force (N)
3. Yarn displacement characteristics

Evaluation of Results

Results are commonly reported as:

ISO 13936-1

• Force (N) required to produce a specified seam opening

ISO 13936-2

• Seam opening (mm) at a specified load

Lower seam opening values generally indicate better seam slippage resistance.

Factors Affecting Seam Slippage

Several factors influence seam performance:

1. Fabric weave construction
2. Yarn count
3. Fabric density
4. Fiber type
5. Sewing thread characteristics
6. Stitch density
7. Seam design

Fabrics with loose constructions are generally more susceptible to seam slippage.

Common Causes of Poor Seam Slippage Performance

1. Low fabric cover factor
2. Loose weave structure
3. Smooth filament yarns
4. Inadequate seam design
5. Improper stitch density
6. Lightweight fabric constructions

Proper fabric engineering and garment design can significantly improve seam performance.

Benefits of Seam Slippage Testing

Manufacturers benefit from seam slippage testing by:

1. Improving garment quality
2. Reducing seam-related failures
3. Supporting product development
4. Meeting retailer specifications
5. Enhancing customer satisfaction
6. Demonstrating compliance with international standards

Conclusion

Seam slippage testing is an essential part of textile quality evaluation, particularly for woven fabrics used in garments and home textiles. Standards such as ISO 13936-1, ISO 13936-2, and ASTM D434 provide reliable methods for assessing seam performance under tensile stress.

Professional laboratories such as METS Laboratories use calibrated tensile testing equipment and standardized procedures to deliver accurate and dependable seam slippage test results, helping manufacturers ensure product quality, durability, and compliance with buyer requirements.