Investigation of Bio-Polishing Effects on CPI, WPI, Stitch Length, GSM & Yarn Count of Different Types of Knit Fabrics

MD. IMRAN HOSSAIN¹, A.K.M ATIQUR RAHMAN², HAMIM ASHRAFI², ABDULLAH AL ZIHAD²

Department of Wet Process Engineering, Shahid Abdur Rab Serniabat Textile Engineering College, Barishal, Bangladesh

Industry Associates: ¹Tropical Knitex Ltd., ²Epyllion Knitex Ltd.

Supervisor: Engr. Pronoy Halder, Lecturer (Textile), Department of Wet Process Engineering, Shahid Abdur Rab Serniabat Textile Engineering College, Barishal.

Introduction

Bio-polishing is a process that removes unwanted fibers from fabric surfaces, often done before, during, or after dyeing of fabric. It relies on cellulase enzymes, which break down long cellulose chains. These enzymes include endo-cellulase, exo-cellulases, and cellobiohydrolases, gradually reducing cellulose to simpler glucose units and eliminating as protruding fibers. Another method, singeing, uses heat to remove fabric hairiness, but it’s temporary and harmful to the fabric’s anti-pilling properties. For a more permanent solution and customer satisfaction, enzymatic bio-polishing is preferred. However, this process can weaken fabric strength. In our project, we used acid-stable enzymes on three fabric types to assess changes in fabric properties.

Materials & Machines

We used three types of knit fabrics (100% Cotton Plain S/J, 100% Cotton 1×1 Rib, and 100% Cotton Interlock), along with chemicals (Acetic Acid, Peroxide Killer, Acid Stable Enzyme), a FONG’S Sample Dyeing Machine, a Dryer Machine, and various instruments (GSM Cutter, Magnifying Counting Glass, Scissors, Electric Weight Balance, Measurement Scale, PH Paper).

Methods

After scouring and bleaching the fabric samples, we measured key parameters such as WPI, CPI, GSM, Stitch length, and Yarn Count. Then, we loaded the samples into the sample dyeing machine using specific chemical ratios for two different companies. The biopolishing process ran for 50 minutes at 55°C and then for an additional 10 minutes at 70°C to deactivate the enzyme. After rinsing for 2 minutes, the fabric was dried in a tumble dryer. We determined CPI and WPI by counting courses and wales in 1 inch of fabric using a magnifying yarn counting glass. GSM was measured using GSM Cutter with ASTM D3786 standards. Stitch length was calculated by marking and measuring 100 wales. Yarn Count was determined by counting and weighing yarns according to a formula. All measurements were taken three times for accuracy.

3. Results & Discussion

3.1. Effects on CPI After Bio-Polishing of Different Knit Fabrics

CPI has a great number of increment found after bio-polishing process. Interestingly, 7.1% to 17.9% CPI increases for Plain S/J, 5.5% to 13.7% CPI increases for 1×1 Rib and 4.9% to 8.3% CPI increases for Interlock fabric.

Table 1: Result of CPI After Bio-Polishing (TKL)

Chart 1: Result of CPI After Bio-Polishing (TKL)

Table 2: Result of CPI After Bio-Polishing (EKL)

Chart 2: Result of CPI After Bio-Polishing (EKL)

3.2. Effects on WPI After Bio-Polishing of Different Knit Fabrics

WPI has also a great number of increment found after bio-polishing process. Interestingly, 9.3% to 12.1% WPI increases for Plain S/J, 7.1% to 10% WPI increases for 1×1 Rib and 6.8% to 8.8% CPI increases for Interlock fabric.

Table 3: Result of WPI After Bio-Polishing (TKL)

Chart 3: Result of WPI After Bio-Polishing (TKL)

Table 4: Result of WPI After Bio-Polishing (EKL)

Chart 4: Result of WPI After Bio-Polishing (EKL)

3.3. Effects on GSM After Bio-Polishing of Different Knit Fabrics

After bio-polishing, GSM is supposed to decrease as biopolishing removes hairy fibers but GSM is increased due to relatively higher stitch density (WPI x CPI) and use of less Enzyme% during the process. For these reasons, GSM has increased from 1.8% to 2.5% for all types of fabric we tested.

Table 5: Result of GSM After Bio-Polishing (TKL)

Chart 5: Result of GSM After Bio-Polishing (TKL)

Table 6: Result of GSM After Bio-Polishing (EKL)

Chart 6: Result of GSM After Bio-Polishing (EKL)

3.4. Effects on Stitch Length After Bio-Polishing of Different Knit Fabrics

After biopolishing, stitch length has decreased from 2.4% to 2.8% for Plain S/J; 2.7% to 3.1% for 1×1 Rib and 2.2% to 2.6% for Interlock fabric.

Table 7: Result of Stitch Length After Bio-Polishing (TKL)

Chart 7: Result of Stitch Length After Bio-Polishing (TKL)

Table 8: Result of Stitch Length After Bio-Polishing (EKL)

Chart 8: Result of Stitch Length After Bio-Polishing (EKL)

3.5. Effects on Yarn Count After Bio-Polishing of Different Knit Fabrics

After bio-polishing, the yarns in the fabrics become finer than before due to reducing the content of hairiness from the fabric surface. That’s why the yarn count has slightly increased after biopolishing process compared to scoured & bleached sample.

Table 9: Result of Yarn Count (Ne) After Bio-Polishing (TKL)

Chart 9: Result of Yarn Count After Bio-Polishing (TKL)

Table 10: Result of Yarn Count (Ne) After Bio-Polishing (EKL)

Chart 10: Result of Yarn Count After Bio-Polishing (EKL)

Conclusion

When we use Bio-Polish on different types of knit fabric, it makes the fabric smoother by getting rid of fuzzy fibers on the surface. This study looked at how 100% cotton fabrics like Plain S/J, 1×1 Rib, and Interlock changed after using cellulase enzyme. The enzyme increased the number of stitches per square inch and made the fabric a bit heavier because we used only a small amount of the enzyme. It also made the yarn finer by removing the fuzzy fibers. So, overall, biopolishing is a great way to make fabric feel more comfortable, shiny, and smooth without causing big changes in other important fabric qualities.

References

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5.         BS EN 14970:2006 (2006) Textiles. Knitted Fabrics. Determination of Stitch Length and Yarn Linear Density in Weft Knitted Fabrics.

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