Calculating Warp Sett and Fabric Weight from Linen Yarn Counts
Calculating linen warp sett and fabric weight requires converting Lea to Tex, applying cover factor limits, accounting for crimp, and factoring in finishing mass losses.
Crimp Percentage
Thread Contraction
Geometric measurements quantify the difference between the length of a yarn in a fabric and the length of the fabric itself. The crimp percentage represents the waviness of the yarn resulting from the interlacing process during weaving. Calculation involves straightening a yarn removed from a measured piece of cloth and comparing the two lengths.
High crimp usually indicates greater elasticity and bulk in the finished linen sheet.
Measurement Method
Testing begins by marking a fixed length on the fabric surface before carefully extracting the warp or weft thread. Tension is applied to the yarn until the waviness is removed without stretching the fibre itself. The crimp percentage is then derived by dividing the difference in length by the fabric length.
This value fluctuates based on the weave structure and loom tension settings. Detailed logs of these tests allow the mill to predict the final shrinkage of the linen cloth. Periodic calibration of the tension meter is required to maintain accuracy across different shifts.
Production Impact
Consistency in this value affects the final dimensions and weight of the exported cloth. If the crimp percentage deviates from the specification, the mill must adjust the take up mechanism on the loom. Proper control prevents shrinkage issues during the finishing and dyeing stages.