Page 27 - 22 Cotton SA magazine

/ QUALITY CONTROL AND STANDARDS

South Africa produces a long fibre, which is
“ Production not always requested by certain spinners. With
more focused and careful management of fibre
programmes must be quality at every step of the value chain, i.e. from
pre-planting to processing, the following spinning
directed towards the requirements are mostly complied with:
improvement of quality • South African cotton has the lowest
by means of providing contamination levels in Africa and is among
the lowest in the world.
guidance and assurances • South Africa produces cotton (80% of the
in production, classing crop) within the standard micronaire range,
i.e. between 3,5 and 4,9.
and ginning.” • South Africa produces cotton with an average
maturity index of 85%, which falls within the
acceptable maturity range.
• More than 60% of fibre strength values fall
Key fibre quality challenges include the within the higher category of 28 grams/tex
following: and better.
• Maintaining and improving fibre length • The staple length of 85% of the crop performs
through better choice of variety, management at 1 / 8" or 1,13–1,15 HVI inches (upper
1
during hot, dry seasons, and preservation of half mean length [UHML]) and longer lengths,
the fibre through harvest and ginning which can contribute to the manufacturing of
• Producing fibre within the optimum micro- quality yarns.
naire/maturity range throughout hot sunny • According to Uster cotton specifications, South
seasons, or cool cloudy spells Africa's short fibre index is described as low,
• High-yield management strategies with an average for machine-harvested cotton
• Reducing nep content through effective defo- of between 7% and 9%, which conforms to
liation and harvest preparation expected norms.
• Better management of fibre moisture in the
field at harvest and during processing through FIBRE PROPERTIES FOR COTTON
the gin SPINNING
• Minimising contamination found in bales Cotton classification is important for spinners,
• Ensuring fibre quality uniformity and consis- for it allows for better selection of raw material
tency within and between years and better control/management of laydowns.
Instrument-based testing provides objective results
THE PERFORMANCE OF THE and reliable data to make good purchasing
SOUTH AFRICAN COTTON CROP decisions. The provision of more data increases
South Africa produces quality cotton that the control of laydown variability and the quality
compares favourably with other international and costs of spinning. Table 1 provides an
cotton-producing countries. Accurate instrument- overview of typical yarn requirements for specific
based, bale-for-bale information on those fibre fabrics and the properties required of the yarn.
properties that affect yarn quality is available Each specification within a category leaves room
to the buyer. This makes the South African to expand upon, for example to include different
crop unique and contributes to the capture of qualities of shirting material.
a better grade and quality in a pooling system. Different spinners will have different end
Fibre-testing results are summarised in quality products in mind, requiring specific fibre
profiles covering all the desired fibre properties, properties when purchasing lint. With more
leading to more consistent bale laydowns being information available and with better control
possible among spinners. This places the spinner of specifications, a more uniform and higher
in a position to buy cost-effective and evenly quality yarn is produced. Table 2 refers to the
distributed running lots. basic requirements of some of the South African

Volume 22 No 3 September 2020 | 27