Shrinkage and Strong Seams

Fabric shrinkage can significantly impact the durability and strength of seams. To minimize adverse effects, we must consider the shrinkage of the fabric and the sewing thread, employ appropriate stitching techniques, and, in some cases, implement pre-shrinking processes, which can help reduce the impact of shrinkage on seam strength. 

Key considerations for fabric shrinkage and seam strength

Shrinkage and Strong Seams
  1. Tension and Stress on Seams
    Fabric shrinkage can exert tension and stress on sewing seams. When the fabric shrinks, it pulls on the threads within the seam, potentially leading to increased tension and stress concentration.
    This tension can weaken the threads and the surrounding fabric, making the seams more susceptible to distortion or breakage, particularly if the fabric and threads have different shrinkage rates.
  2. Seam Distortion
    Fabric shrinkage may cause distortion in the seam, altering the garment’s original shape and fit. This distortion can lead to uneven stress distribution along the seam, affecting its strength.
    Seams that experience significant distortion may be more prone to unravelling or tearing, compromising the garment’s overall durability.
  3. Thread Tightness
    Shrinkage can result in thread tightening, which increases stress on the thread and fabric fibres and causes them to weaken over time.
    The fabric’s shrinkage must match the sewing thread’s shrinkage, which is essential to balance tightness and flexibility.
  4. Choice of Stitch Type
    The choice of stitch type can influence how well a seam accommodates fabric shrinkage. Certain stitches, such as lock stitches or reinforced stitches, provide better stability and resistance to unravelling, even in the presence of shrinkage. However, zigzag or stretch stitches may be suitable for fabrics with higher shrinkage rates, allowing the seam to accommodate the dimensional changes.
  5. Pre-Shrinking Techniques
    Manufacturers often pre-shrink fabrics before garment production to minimize post-construction shrinkage. This pre-shrinking helps stabilize the fabric and reduce the potential impact on seam strength.
    Pre-shrinking sewing threads will also contribute to seam durability.
  6. Testing and Quality Control
    Rigorous testing for fabric shrinkage and seam strength is essential during the development and production stages. That helps us to identify potential issues and implement necessary adjustments. The process involves prewashing or pre-treating the fabric in similar conditions to those it will experience during the use. Then, measure the dimensional changes to assess the degree of shrinkage.
  7. Consumer Care Instructions
    Providing accurate care instructions to consumers is crucial. Communicating how to launder and care for garments, especially regarding potential shrinkage, empowers consumers to maintain the durability of their clothing.

Testing Shrinkage

The most widely used standards for measuring shrinkage in fabrics are:

  • ISO 5077: Textiles – Woven fabrics – Determination of dimensional change after laundering
  • ASTM D1930: Standard Test Method for Determining the Directional Change of Length of Woven or Knitted Fabrics

The test involves:

  • Cutting fabric specimens in warp (lengthwise) and weft (width-wise) directions according to specified dimensions.
  • Conditioning the fabric specimens in a controlled environment with specific temperature and humidity.
  • Marking reference points on the conditioned fabric specimens.
  • Laundering or dry cleaning the specimens according to the intended care instructions for the garment.
  • After laundering/cleaning, the specimens should be dried following a standardized drying procedure (tumble drying, flat drying, etc.).
  • Re-conditioning the dried specimens in a controlled environment.
  • Measuring the distance between the reference points on the conditioned and dried specimens.
  • Calculating the percentage change in length (shrinkage) for both warp and weft directions.

Additional Considerations:

  • Specimen Size: The size of the fabric specimens can impact the shrinkage results. Larger specimens might exhibit slightly less shrinkage than smaller ones.
  • Washing/Cleaning Cycles: The test method should specify the washing or cleaning cycle used, as harsher cycles (higher temperatures, stronger detergents) can induce more significant shrinkage.
  • Drying Method: The drying procedure (tumble drying vs. flat drying) can also influence shrinkage results.

 

Shrinkage and Strong Seams

By incorporating these standard laboratory tests and methods, we can accurately predict how much the fabric or garment will shrink after laundering or cleaning. That allows us to select appropriate fabrics with minimal shrinkage potential, adjust garment sizing accordingly, and provide clear care instructions to consumers.

This information is a part of the extensive research conducted for our third book, Strong Seams, a seam catalogue focused on garment durability and quality. 
We couldn’t include all the research in the book. However, we believe it’s worth sharing with people like you who are also interested in quality and long-lasting garments.

We hope the material is helpful. If you want to know more about our book Strong Seams, please visit the following link: book Strong Seams (link)

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