Contamination: with an Employee Picking Lint from 3 to 5 Bales and Feeding It Into the Blending and Carding Machines
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PHYSIOLOGY TODAY Newsletter of the Cotton Physiology Education Program — NATIONAL COTTON COUNCIL October 1990, Volume 2, Number 1 Contamination: with an employee picking lint from 3 to 5 bales and feeding it into the blending and carding machines. If An Industrywide Issue a piece of twine or cloth appeared in the bale, he Doug Herber, Bill Mayfield, Chess would pull it out. Howard and Bill Lalor Modem machinery has replaced these workers, with robotics and automated systems now doing Over the last year, Cotton Physiology Today has cov the work. The modem opening and blending proc ered man~ topics relatin~ to p1ant growth and man agement. Economic healTh requires more than just ess automatically feeds multiple bale laydowns.lf efficient production; it also requires efficient and contaminants exist, this automated, large-scale sys profitabTe marketing. Because of the fnreat from con tem can blend them from one bale with lint from tamination to U.S. cotton's reputation and recent many other bales. Take, for example, one contami gains in market share both at home and abroad, this nated bale that goes undetected and is blended with Issue focuses on contamination, why it should be 29 contamination-free bales in a laydown. When avoiaed and how. three of these laydowns are then blended together, History of Cotton Pricing the potential exists for 45,000 pounds of contami Historically, the price of cotton has been based nated cotton. Again if undetected, yams manufac largely on reputation. Before government classing, tured from these contaminated cottons may be each growing region had a reputation for producing blended with contamination-free yams to produce a certain fiber types (S.E. coastal region = Sea Island fabric - thus creating the potential for many thou Cotton, Mississippi Delta and tributaries = long and sands of square yards of contaminated fabric fmm strong fiber, Southwest desert = short and coarse). one contaminated bale. With establishment of the Universal Quality Stand Although fabrics are periodically checked, if un ards in 1914, more of the price could be based on detected the contaminated fabrics may be sewn into bale quality because a common language for grade finished goods resulting in the highest losses. Sewn and length could be used to describe what qualities and finished goods are the most costly place to lo were available at what price. No longer did a cotton cate contaminants because so many processing broker have to look at each bale sample. As more steps have occurred and the value added to the raw measurements of quality are added, micronaire in product is greater. The bar chart below illustrates 1966 and strength, color, trash and elongation in the increased loss during each stage of mill process 1991, the price of a bale can be determined more by ing. Losses in finished goods are at least 1,000 times its measured quality and less by its reputation. But more expensive than when a contaminant is found even under HVI, many important quality features in the bale prior to blending in the opening room. are not measured and, as is natural, price will con tinue to be determined in part by reputation. The Dollar Loss From Contaminants one unmeasured factor that places the greatest blem $350,000 ish on cotton's quality reputation is contamination from unnatural sources. finished goods Contamination and Modern Spinning Equipment Contaminants are an increasing problem as gins and mills utilize more sophisticated equipment and $210,000 remove the human element. In the 1/ old days" of gin ning and textile manufacturing, an army of workers weaving monitored the conversion of seed cotton to fabric. In or older gins, watchful eyes handled suck pipes, knitting whereas today's modem gins employ automatic $70,000 module feeders. In the opening room, where bales $17,500 are laid down and fed into the blending and clean $350 carding ing machines, the work used to be done by hand, laydown I I EJ Lint cleaning, whether in the gin or mill, relies Grease and Oil upon physical differences between the fiber and the Grease and oil account for about 5% of the prob contaminant for the basis of separation. If the con lems reported. Most grease and oil contamination taminant is heavier or larger or even shaped differ now appears to be coming from within the bale it ently, engineers have been able to design separation self. Possible sources include excess lubrication in machines. however, when the contaminant is of harvesters or ginning machinery. Grease build-up similar size, shape and weight as lint (as are our ma from over-lubrication of spindles is a problem that jor contaminant problems), then it is virtually impos can be reduced by steam cleaning picker heads at sible to remove them prior to the irate shopper the start or end of each day. In addition, leaks in hy returning the defective goods. Polypropylene twine draulic lines or worn seals on module builders or is the No.1 contaminant problem, partially because bale presses can lead to oil contamination of seed of its similarity in size, shape and weight to cotton cotton and lint. lint. Rubber Contaminants Have Changed over the Years Rubber continues to be a major contaminant, ac Contamination has always been a concern for tex counting for about 15% of the problems identified. tile mill processors. However, over the years con One possible source is rubber doffers on cotton pick taminants have changed. In the late 1970's ers. If adjusted too tight, spindles can grind doffers approximately 25% of all contaminants originated and create thousands of small pieces of rubber mate from plastic materials, 25% originated from rubber rial which are mixed in with seed cotton. Because materials, and about 50% from grease and oil. these rubber pieces created by over tightened spin Grease and oil contaminants were coming primarily dles are similar in size and shape to cotton lint, they from the bale surfaces, where exposed cotton had cannot be removed during seed cotton or lint clean come in contact with grease and oil in storage and ing processes. transportation. Bale packaging programs that pro moted improvements in packaging materials and If spindle twist is occurring, moistener systems fully covered bales have helped to eliminate these should be checked instead of tightening down on problems. In 1970, 100% of the U.S. bales had ex spindles. An alternative is to use non-contaminating posed sides, while in 1990 all of the bales are fully doffer materials. If adjusted too tight, these materi covered except for the sample holes. Additionany, als break off in chunks rather than small slivers. an industry push led to the establishment of stand These chunks, similar in size to sand and dirt, can ards for bale conditions which help to assure that be removed in normal cleaning procedures. The Na bales arriving at textile mills are in satisfactory con tional Cotton Council's Committee on Quality As surance and Education has set a date of 1993 for dition. release of alternate doffer materials. Both Case I.H. Contamination continues to be a problem in the and John Deere have indicated they are currently re textile industry, but again, the contaminants have searching alternate materials. changed. Reports received within the last year indi cate that contamination from grease and oil makes Bunge cords when used to hold down module up only about 5% of the total problem. Rubber now covers can also get into the seed cotton and be accounts for approximately 15% of the problems. ground into black strings in the gin stand's seed roll. Plastic accounts for about 50% and apparel fibers The gin stand is where lint is pulled from the seed. 25% of the problems. The remaining 5% comes from Unfortunately this is also the place where hats, other materials such as paint a'nd metal. shirts, rope etc. can get recycled and ground into lint size particles, turning high quality lint into "newspa Distribution of Contaminants per grade" contaminated cotton. Plastic 50% Almost 50% of all contamination problems are Plastic caused by plastic. Plastic fibers found in cotton fab ric include every possible color: black, red, blue, or ange, purple and lavender. However, rarely do these contaminants originate from bale packaging materi 250/0 als. So where do they come from? In today's dispos Apparel able society, plastic trash on the roadside becomes Fibers 15% 5% man-made tumbleweeds, spreading the seed of con Grease 5% tamination into cotton fields near popUlation cen IRUb~rl and Oil Other ters. These materials can be picked up by harvesters , , .'-_ ..' and incorporated in seed cotton. Producers should Metal checks fields as they are being picked - especially Other materials which are sometimes a problem, those near traveled roadways - to insure that trash although rarely, are large foreign objects in bales. has not blown in during the night. When cotton was hand picked, this kind of contami Polypropylene or other twine used to hold down nation in seed cotton was not always accidental. Ma covers on modules or trailers accounts for a large terials such as metal flashing, wire and tools have percentage of the plastic contamination in bales. been found inside bales. If not caught in time, mate Cords may be left on modules and become entan rials such as these can cause equipment damage, gled with seed cotton and be pulled into a gin's suc fire and possible injuty. tion pipe or module feeder. The twine can become broken up by gin equipment and contaminate sev Spray Paint eral bales of lint. To avoid problems from module tie Another item which is a potential contaminant is downs, it is best to use cotton rope to secure covers.