The effect of fabric strain during pressure steaming on fabric dimensional properties

It is shown that tension applied to fabric which is then permanently set by steaming under pressure for a short time has a significant effect on fabric dimensional properties. Increasing levels of stretch applied to fabric before pressure steaming resulted in decreases in fabric hygral expansion and relaxation shrinkage and also lowered fabric shrinkage that resulted from permanent setting. The setting conditions resembled those used in conventional pressure decatising, and it is suggested that in batch decatising, precise control of the length and width of fabric as it is batched up with the wrapper before steaming under pressure could enable predictable changes in fabric dimensions, relaxation shrinkage and hygral expansion to be obtained.

The dimensional and mechanical properties of wool/polyester fabrics made from vortex and ring-spun yarns

Fabric woven from wool/polyester (PES) Murata vortex spun (MVS) blend yarn is a commercially viable proposition particularly on the basis of advantageous wear-resistant properties, compared with fabric made from traditional worsted ring-spun yarn. However, in some early industrial trials with fabric made from 45/55-blend wool/PES MVS yarn, significantly greater relaxation shrinkage was found relative to comparable worsted ring-spun fabric. It was noted at the time that the amount of relaxation shrinkage in MVS fabric could be reduced to a large extent by using steamed MVS yarn.

In this study, the extent of variations in the dimensional and mechanical properties of fabric samples woven from a combination of steamed and unsteamed MVS yarn and equivalent worsted ring-spun yarn is examined. In general, greater hygral expansion and relaxation shrinkage were found in loom-state fabrics made from unsteamed MVS yarns, whereas the fabric made from steamed MVS and ring-spun yarns gave relatively low levels of relaxation shrinkage and hygral expansion. Permanent setting of fabrics, by pressure steaming, was found to be more effective than yarn pre-steaming in reducing relaxation shrinkage levels of fabrics made from unsteamed MVS yarn. After pressure steaming, all fabrics showed similar levels of relaxation shrinkage and hygral expansion.

Permanent setting of the fabrics, by pressure steaming, resulted in similar levels of relaxation shrinkage and hygral expansion, irrespective of the yarn production method; relaxation shrinkage fell to around 1% and hygral expansion increased by about 1%, relative to the loom-state samples. MVS fabrics were relatively heavier and fuller and had a firmer handle than the worsted ring-spun fabrics, reflecting the greater fabric weight, thickness and shear rigidity measured on these fabrics. These attributes are associated with different structures of the worsted ring-spun and MVS yarns used to make the fabrics.

A study of dimensional changes in wool fibres and fabrics

Wool fabric dimensional properties were found to be influenced by the temperature and pH of the fabric, and on the fabric tension during pressure steaming. The results show that improvements can be made to standard methods for measuring fabric dimensional properties, and to the design of commercial finishing steaming equipment.