Calibration Cotton Standards for High Volume Instrument

In the liberalized quota-free textile trade, quality of both the raw material and finished goods has gained importance than ever before. Testing laboratories, therefore, are viewed as vital links connecting manufacturers, traders and consumers. The emergence of accredited laboratories and Mutual Recognition Agreements among accreditation bodies of different trading countries are manifestations of growing importance of quality in international trade. CIRCOT being one of the oldest accredited institution for textile testing in the country and a premier National Institute known for its research and development accomplishments on Post harvest processing of cotton has been performing its role as a quality service provider to the textile trade and industry.

It is well known that the fibre quality assessment through objective measurement of fibre attributes is carried out using state-of-the-art instruments like the High Volume Instrumentation System that need calibration using what are known as “Calibration Cottons” the Standard Reference Materials . Till 1997, the United States Department of Agriculture (USDA) was the only accredited agency qualified to produce these reference materials. Import of calibration cottons involves time, foreign exchange and arduous procedural wrangles for import.

The circumstances that led to CIRCOT’s preparation and supply of calibration cotton during late nineties to the textile industry in India are now part of history. With USDA discontinuing its supply of ICC mode calibration cottons, under an ICAR Revolving Fund Project, the Institute embarked itself on an exciting programme of making available this reference material for the industry. Two sets of standards one for conventional instruments and the other for HVI are being produced and marketed under this programme. The novelty of the CIRCOT HVI standards is that the same calibration cottons are useful for both ICC and HVI mode operation.

The Institute has been able to create a customer base of more than 350 users who seem to be satisfied with both the quality and service as gauged by their repeat orders.

With years of experience in preparation of calibration cotton, CIRCOT has developed a processing flow chart and screening procedure for preparation of calibration cotton within acceptable standard and tolerance limits. Some of the important points that are carefully followed so as to meet the requirements of cotton as a reference material are as follows:

  • (1) Basic cotton is normally sourced from breeding stations, wherein the  high   purity of seeds  are ensured  and   best  management practices are put in place,
  • (2) Judicious selection of machinery is made from a wide range of various types  of opening  and   cleaning   machines  available  at CIROT spinning pilot plant so as to ensure optimum preparation with minimum variation of fibre quality,
  • (3) Provision exists for optimum selection of speeds and settings of opening and cleaning machines as per the fibre characteristics,
  • (4) Thorough and homogenous mixing of fibres are ensured,
  • (5) Testing of uniformity is done by collecting random samples from different stages and periods of production,
  • (6) Calibration cotton produced by CIRCOT is within the quality factor tolerance signifying  homogeneity in preparation and sample integrity as a reference material.

Quality Factor Tolerance

2.5 % span length (mm)±0.5
Uniformity ratio (%)±1.0
Micronaire value (|ag/inch)±0.1
Tenacity (3.2 mm) (g/tex)±1.5