International buyers of cotton are increasingly looking at the length uniformity index (LUI) as an indicator of how well the fiber will work on their ring spinning machines.
Unfortunately, says Vikki Martin, associate director of fiber quality for Cotton Incorporated, “This is one fiber quality trend for U.S. cotton that has declined over the past several years. We've taken a pretty good hit in the international marketplace on LUI.”
In 2004, she told members of the Southern Cotton Ginners Association at their annual meeting at Memphis, “only 41 percent of the U.S. crop met this highly desirable quality level for the international market; in 2005, only 17.2 percent; and in 2006, only 29.9 percent.”
U.S. textile mills, Martin noted, predominantly use open-end rotor spinning equipment; for them, strength is the most important fiber quality parameter.
“In the overseas market, they mainly use ring spinning equipment and fiber length is their No. 1 fiber quality factor. Strength in a ring spinning operation is directly related to fiber length.”
The change in the U.S. cotton industry from a chiefly domestic market to one that's export driven has brought significant changes in the fiber qualities that buyers want, she said.
“Less than 10 years ago, we were using 70 percent of the cotton produced in the U.S. in our domestic textile mills. Now, most of our cotton is going to the international market.”
The base quality that international buyers are expecting, Martin said, “is higher than what we've traditionally produced in the United States. Now, they're wanting 35-26 staple, 27-28 grams per tex, 3.8-4.6 micronaire, 82 length uniformity index or better, 21-31 color grade, and 2-3 leaf grade.
“Those higher expectations by foreign mills are based in large part on tradition and logistics — they traditionally have bought higher quality than they needed because, so far away, they don't have the luxury of getting another shipment next week.
“And with their utilization of ring spinning equipment, there is now also a strong manufacturing reason for specifying higher quality.”
An analysis of the U.S. crop over the past two years shows just over 30 percent would meet the minimum quality expectations of international buyers, Martin said.
As for the increasingly important LUI, she said, “Unfortunately, we don't really know what impact variety, weather, and other influences have on this. We do know that, going forward, breeders are going to need to pay more attention to things such as fiber length distribution.”
Comparing the U.S. and Chinese cotton crops, “We can see that they consistently have a higher LUI than we do.”
Neps (immature cotton fibers) are another concern in the cotton quality equation, Martin said.
“You don't know they're there until they show up in the fabric and it's too late to do anything about it. Neps won't dye, resulting in white specks in the fabric.
“Seventy-five percent of the world's cotton is still harvested by hand, which results in fewer neps. U.S. conventionally-harvested cotton averages 250 neps per gram; stripper cotton 360 neps per gram; while the world average is only 150 neps per gram.”
The No. 1 controllable quality issue for U.S. cotton, Martin said, is contamination.
“We enjoy an excellent reputation for having very low levels of contamination, but there are still problems with plastic Wal-Mart bags, bird feathers, etc. International buyers would like a guarantee of 100-percent contamination-free cotton. That's totally unrealistic, but anything we can do to further minimize this problem will be to our advantage.”
China is the largest textile producer in the world, Martin noted, and “huge increases in textile consumption occurred in that country from 2002-2005. That's expected to continue.
“Merchandisers there have been taking a lesson from the U.S., studying what consumers want and targeting their products to specific ages and buying groups. The Chinese retail market is mainly women ages 20-34, and the leading shopping item is clothing, even ahead of food.”