1. Shrinkage and the Reference State
STARFISH Workshop

2. Fabric Dimensions
The basic dimensional unit of a knitted fabric is the loop
The dimensions of any fabric are simply a reflection of the shape and size of the loops
STARFISH Workshop

3. Shape and Size of Loops Depends on: Knitting variables
Type of wet process
Stretching during processing
Relaxation treatments
STARFISH Workshop

4. Major Knitting Variables
Are:
Type of yarn
Count (size, number) of yarn
Stitch length
Size of knitting machine
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5. Type of Wet Processing Wet processing affects: Yarn weight Yarn length
Yarn diameter and stiffness
Yarn twist liveliness
Amount of change depends on process type
STARFISH Workshop

6. Stretching During Processing
Stretching the fabric affects:
Ratio of length to width
Weight per unit area
Shape of loops
Amount of change depends on process type
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7. Relaxation Treatments
Shrinkage is only the relaxation of processing strains
Therefore the fabric must be allowed to relax after wet processing
The most effective relaxation process is tumble drying
STARFISH Workshop

8. Prediction of Shrinkage
If we want to control shrinkage then we must be able to predict it
In order to predict shrinkage, we have to be able to predict the dimensions that the fabric will have
AFTER THE SHRINKAGE TEST
STARFISH Workshop

9. Shrinkage Shrinkage Sample Original Dimensions
If we know the Relaxed Dimensions …
… then we can calculate the Shrinkage
Relaxed Dimensions
STARFISH Workshop

10. What is the Real Shrinkage?
Shrinkage is not constant:
Different methods give different results
Customers use different methods
Different laboratories disagree
We need to know the maximum level
STARFISH Workshop

11. Distortion Distortion is why fabrics shrink
A manufacturer never sees an undistorted fabric
Neither does a retailer
Only the final consumer does
A rational system of fabric engineering and quality assurance …
… needs a sound basis for making comparisons of distortion levels.
STARFISH Workshop

12. Distortion and Shrinkage
Shrinkage is OK for a pass/fail test but:
it is not very reliable
it is not very informative
It does not distinguish between
poor product design
poor manufacturing technique
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13. Finished Fabric Specification
Standard Grey Fabric
Poor
Good
Finished Fabric Specification
High
Low
Laying-up and Sewing Tensions
Standard Garments
Different sizes after laundering
STARFISH Workshop

14. Measuring the Height of Mountains
Who sees the true height?
Neither !
Baseline Reference is Sea Level
STARFISH Workshop

15. Shrinkage Testing
Can never be a fundamental basis for product design or quality assurance
What we need are the dimensions of the fabric after complete relaxation
These reflect the true nature of the product
STARFISH Workshop

16. Effect of Laundering Conditions
Average Shrinkage % 2 4 6 8 10 12 14
1x1 Rib T-shirts (Retailer A)
Tumble Dry
Line Dry
Length Shrinkage
Cycle Number 2 4 6 8 10 12
STARFISH Workshop

17. Effect of Laundering Conditions14
1x1 Rib T-shirts (Retailer A) 12 10
Tumble Dry 8
Average Shrinkage % 6 4
Line Dry 2
Width Shrinkage 2 4 6 8 10 12
Cycle Number
STARFISH Workshop

18. Changing the Drying Method2 4 6 8 10 12
1x1 Rib T-shirts (Retailer B)
Width
Average Shrinkage %
Length
5 x W+TD then 5 x W+LD
Cycle Number
STARFISH Workshop

19. Changing the Drying Method2 4 6 8 10 12
1x1 Rib T-shirts (Retailer B)
Width
Average Shrinkage %
Length
5 x W+LD then 5 x W+TD
Cycle Number
STARFISH Workshop

20. Shrinkage During Tumble Drying
Length Shrinkage % 4 8 12 16 20
Interlock – after bleaching
Length
Width
Drying
Moisture Regain After Tumbling 20 40 60 80
100
STARFISH Workshop

21. Length Shrinkage in Tumble Drying
Proportion of Total Shrinkage
0.0
0.2
0.4
0.6
0.8
1.0
1.2
20 different fabrics
Cycle Number 2 4 6 8 10 12
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22. Laundering Conditions
Summary of research findings:
Tumble drying produces the relaxation
Samples must be thoroughly dry
Washing conditions not critical
Softeners increase variability
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23. Developing a Reference Method
Multiple cycles including tumble drying
Ten cycles best
Five cycles acceptable for research
Two/Three cycles OK for routine QC
One cycle not enough in any case
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24. STARFISH Reference Procedure
Full wash programme at 60 °C
Tumble dry (completely dry)
Rewet on rinse cycle
Repeat three more times
Condition
Fabric is now in the “Reference State”
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25. STARFISH Reference State
Fundamental to STARFISH Technology
Foundation for the computer predictions
A basis for making valid comparisons
For product development
For process control
For calibration
STARFISH Workshop

26. STARFISH Workshop