Raw cotton destocking could bring quality issues for spinners

The price may be attractive, but cotton which has been in long-term storage is a risky purchase 

Uster, Switzerland – As worldwide stocks of cotton continue to build up, spinners might be eagerly anticipating a period of lower prices for their raw material. But there are serious risks ahead, particularly when the market is likely to be flooded with some cotton which has been stored in warehouses for lengthy periods.

This issue was highlighted at the recent ITMF Conference in Beijing and the ICAC Plenary Meeting in Thessaloniki, with experts warning that stockpiled cotton can degrade over time.  Quality problems are inevitable: color loss (‘yellowing’) and deterioration of spinning quality are the biggest concerns. Accurate testing with USTER® HVI 1000 is the only sure way to check that cotton supplies are fit for purpose.
Prices on world cotton markets look set to fall, against a background of inventory levels which have risen massively over recent years. It is estimated that more than 100 million bales now sit in warehouses around the world – a stockpile which would supply the entire textile industry for a whole year. China alone has more than half of this total inventory, at 62 million bales, which would be enough for two years of domestic textile needs in this, the largest single cotton-consuming, country.

Cotton growers are bound to cut back outputs as demand falls and the cotton supply chain starts destocking on a large scale. So, is this good news for spinners, if a glut of lower-priced cotton is soon to hit the market? The answer is ‘probably not’ – if spinners forget the ancient Roman maxim ‘Buyer Beware’.

Storage effect on cotton quality

The big problem is likely to center on how long the cotton stocks have been warehoused, and under what conditions. It is an acknowledged fact that raw cotton quality declines over time, even when stored in excellent conditions. The major issue is loss of color grade, often referred to as ‘yellowing’ – and it is not always readily apparent without proper testing. So, a cotton may emerge from the gin and into the warehouse with excellent quality ratings, recorded and tagged at this point. But, over time, color degradation will take its toll on the quality level, especially when the cotton is warehoused for long periods.

Special attention should be paid to cotton sourced from areas with enormous stockpiles, where storage options are often poor, with farmers keeping cotton loose in sheds, exposed to changing environmental conditions and moisture – a clear quality risk.

In the near future, there will be acts to balance mill consumption with cotton production. One way will be to cut back on imports, so that domestic mills will buy warehoused supplies. But if Chinese spinners are aware that this cotton may have been in the warehouse for as long as three years, they might baulk at the potential quality risks it carries. In those circumstances, some of these supplies might be unloaded to world markets – spreading the risks to spinners everywhere.

Customers who purchase cotton which has been in long-term storage will almost certainly not be able to rely on the quality data tagged on the bales. And this can affect the value – the price paid may be higher than it’s really worth – as well as the quality performance of the cotton through yarn production and into the finished fabric. Careful testing of incoming cotton for key quality parameters is vital if spinners are to avoid these potentially serious problems from damaging their business prospects.

Is color grade really important?

Color grade is a key driver of raw cotton pricing, always a factor in buying and selling negotiations. That is because a number of serious fabric faults can be traced back to color grading issues. It is essential that spinners know exactly the correct color data for every cotton purchase, so they can ensure that mixing of the bales at the start of the spinning process is appropriate for the yarn quality being produced.

Extensive testing of color degradation of cotton under various environmental conditions has resulted in clear evidence of the seriousness of the problem. The longer that cotton is in storage, and the worse the warehousing conditions, the quicker and more severe will be the loss of color grade.
Even in an ideal storage environment, in a cool and dry warehouse, cotton that is kept for more than a year will start to degrade. If conditions are unsuitable – a hot and humid warehouse, for example – the ‘yellowing’ will occur after only six weeks.

The impact on spinners

Most spinners will be fully aware of the risk of color grade loss with cotton that has been in long-term storage. But the effect of the storage conditions on this problem is less widely known. In any case, it may often be impossible for spinners to check on the detailed warehousing environment of a cotton purchase.
What spinners will realize only too well is that yarn quality can be drastically affected by inaccurate color grade data. The defect known as barré is an unwanted striping effect in woven or knitted fabric, which becomes visible only during fabric manufacture or even at dyeing – the worst possible times to detect off-quality. The barré effect can be caused directly by inaccurate color grade data, often taken from outdated bale tags. As has been explained, quality tags on the bales are only completely valid for the time of issue. So spinners can be faced with costly quality claims and lost reputation for this single issue.

David McAlister, Product Manager for Cotton Classing within Uster Technologies, says: “Relying on data that does not represent the current quality of the cotton results in unavoidable issues of unforeseen enormity, with repercussions along the entire textile value chain in terms of both quality and profitability – and spinners will be the ones in the firing line.”

The only sure safeguard

The solution for spinners is effective cotton classing, in other words re-testing raw cotton samples before making a purchase decision. For this task, the USTER® HVI 1000 is the globally-accepted instrument, used to set cotton calibration standards by the world’s leading cotton authorities, including USDA in the USA, CFIB in China and many other national bodies. The HVI® provides fast and accurate data on color grade levels, so that spinners can compare quality data from bale tags with their own test results. Not only does it give them security that their cotton purchase is good value, it also helps to determine the optimum mix of qualities for the start of the spinning process.

McAlister says: “The USTER® HVI 1000 will not only prevent pricing and quality problems, it will also provide a rapid payback on the initial investment in the system. It will give spinners confidence that the yarn quality they are producing will be exactly what their customers have ordered.”

McAlister points to a 2002 study by Cotton Incorporated for some stark illustrations of the financial impact of the barré problem – and the massive cost savings possible with the USTER® HVI 1000. “The study showed that producing fabric with barré costs about 21,400 Euros (USD 27,000) for every 1,818 kg (4,000 lbs.) of fabric. That means a typical 50,000-spindle mill, producing 30,000 kg of standard-count yarn per day, would be losing 400,000 Euros (USD 500,000) each day. At this rate, a single day of preventing barré would more than cover the investment cost of HVI® instrumentation – as well as protecting hard-won profit margins.”

“Rising worldwide yarn quality requirements and the realistic risks from long-term raw cotton stocks cannot be ignored. There could be a serious impact on world markets for many years to come. But the situation also presents an opportunity for smart spinners who can deliver consistent yarn quality levels supported by accurate raw material testing.”


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