Shrinkage

Shrinkage refers to the change in dimensions of sewing thread due to thermal or hydrothermal effects. The change in length, which is usually negative, is expressed as a percentage of its original length. This quality characteristic is particularly important for the subsequent product quality. Cleaning and finishing processes such as washing, dry cleaning, steaming and ironing must not cause the sewing threads and embroidery threads in the finished product to shrink.
 

Factors influencing sewing thread shrinkage:

• The sewing thread itself:
  • Raw material
  • Construction

  • Manufacturing process (stretching/drawing, heat setting, dyeing)

     

• Thermal or hydrothermal exposure
  • Treatment temperature
  • Exposure time
  • Type of medium (water, steam, hot air, etc.)
  • Stress state

AMANN conducts shrinkage testing in accordance with DIN 53 866. Length measurements are taken before and after treatment in the respective medium using simple suspension and measuring devices. The test is carried out using the so-called strand measurement method and with a preload force that depends on the linear density. 

AMANN tests both thermal and boiling shrinkage using the following parameters:

• Thermal shrinkage:  180°C, 15 min., in a thermal cabinet
• Boil shrinkage:  95°C, 30 min., in boiling water

The thermal shrinkage parameters simulate a finishing treatment, while boiling shrinkage simulates the stress of the washing process. These results help to coordinate the respective thermal and mechanical parameters for sewing thread production. This enables AMANN to ensure compliance with the lowest shrinkage values.