Worth Reading

Determining knitted fabric elastane content by Koos Snijders (ex Lycra)

The author of the tech-book comments: I’m proud and excited launching my first technical textile related book titled: “Determining knitted fabric elastane content”. The sub title: “Controlling cost of elastification, quality, quality consistency of knitted fabrics and garments by quantifying and controlling fabric elastane content accurately”.

The 180-page book got 3 main chapters: (published in August 2020):

•       Determination of greige knitted fabric (stemming from small & big size CK & WK machines) by manual separation of the knitted yarns, correcting for the finish oil and relaxing the fabric specimen.

•       Determination of D&F knitted fabric / garments by chemical separation of the yarns: dissolving the elastane yarn or dissolving the ground yarn.

•      The more interesting method for determining the greige fabric elastane content – and this can be done in a very accurate way – is to perform well defined measurements at the CK knitting machine start-up and simply calculate the elastane content. It is being explained how to make corrections for the finish oil and the so-called “Package-Relaxation” level and “Package-Relaxation-Profile” of the used elastane yarn (read: PR-level / PR-Profile or yarn stretch on the bobbin).

The book’s cover

For warp knitted fabric, the calculations refer to the spinning process, the warping process (beaming process) and the knitting process. And in addition, take the PR-level and the PR-profile of the warped elastane yarn onto beams into account.

The major advantage of this method is that ( CK & WK ) fabric quality and fabric quality consistency can be controlled already at start-up of the machine: avoiding producing and shipping fabrics and garments without actually knowing that the quality will be right.

An additional chapter summarizes the accuracy of each method and apart from the theory and examples, there is a separate procedure on how to perform each method. The separate procedures can be implemented in the site quality systems easily. Pictures, tables and graphs give a good insight in the different technologies.

There are multiple attachments listing spreadsheets and calculators for rapidly computing the fabric elastane content. Each spreadsheet lists the applied Excel formulas which makes it easy composing own calculators.

The fabric elastane content: this can refer to the elastane content of a specific sample or specimen but of course the more interesting information is how to determine the CK or WK creel related fabric elastane content. One attachment explains how to set the knitting machine (the so-called Standard Operating Condition Document) and another attachment provides an example of how to describe the finish fabric and its quality (Fabric Specification).

Applying the information, setting the machine correctly, and correcting for the PR-level, the PRL-profile, it possibly can lead to 4-6% fabric elastane content reductions and at the same time improve fabric quality and fabric quality consistency.

The book reveals several novel techniques and the information can be used by fabric / garment manufactures and buyers during contract negotiations or to establish the circumstances under which the quality and consistency of the fabric / garment needs to be produced and tested in order to better control the entire supply chain e.g. when selling to or importing from other countries or even regions. Simply knowing that the produced fabric (at machine start-up) meets all manufacturer and final customer specifications and expectations.

The comprehensive manual will be appreciated by technicians and quality managers producing quality fabrics and garments but the manual would also help academics, textile school students and textile institutes to broaden their knowledge in the world of elastane yarn and elastane elastified fabrics / garments.

Books can be ordered bysending mailto the author: Kooss29@XS4all.nl