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The cotton fibre is a single biological cell which grows from a single seed. The outer primary wall grows in the first 15 to 20 days, after which a secondary wall fibre grows for another 25 to 40 days. This layered arrangement of the cellulose and noncellulosic walls gives it a birefringent property and utilising this property, a patent pending optical setup was developed.

Using our unique light setup, the inner cell wall illuminates with a red hue with an intensity proportional to the maturity of the fibre. This can be seen in the following image. The image shows fibres of similar widths, but the mature fibres are filled with a red hue and the immature fibre has a lack of colour and appears translucent.

Immature fibres are:

• weaker, causing more breaks and shorter fibre length
• has more entanglements, causing neps
• take-up less dye, producing uneven colour in the final fabric

Fineness is proportional to the cross sectional area of the fibre and is expressed in micrograms per meter. Finer fibres give a more even yarn and create fabric with a softer feel. Samples are prepared, cut and weighed on a single module shown in the following image. The module contains a guillotine with a 0.7mm blade and a weighing station accurate to 1/1000th of a gram. The fineness measurement is performed at the same time as the maturity measurement.

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