Roller ginning provided the first mechanical means of separating cotton lint from seed. The first true roller gin was the Churka gin, which produced up to 2.3 kg (5.0 lb) of lint/day. In 1840, the McCarthy gin was invented to gin extra-long-staple (ELS) cotton. Although the ginning capacity of the McCarthy gin was a major improvement over the Churka gin, capacity was limited to about 18 kg (40 lb) of lint per hour. In the late 1950s and early 1960s, a rotary-knife roller gin was developed. The rotary-knife roller gin had a ginning rate 12 times higher than the McCarthy gin, though the rotary knife gin still processed cotton at only about one-fifth the rate of a saw gin with an equivalent width. Around 2005, commercial development of a high-speed rotary-knife roller gin was accomplished. The high-speed roller gin processes cotton at approximately the same rate per unit width as a saw gin. The high-speed roller gin not only allows ELS cotton (such as Pima) to be ginned more efficiently, but also permits high-quality Upland cotton to be roller ginned at a rate more comparable with the saw gin while achieving the benefits of better fiber quality resulting from roller ginning. Although variations of the McCarthy gin are used today in many countries to gin ELS cottons, the rotary-knife roller gin is the only type of roller gin used in the U.S.

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Abstract. Cotton post-harvest processing research requires moisture content determination for seed cotton, cottonseed, and lint. Methods for determining moisture content have changed and are no longer consistent between laboratories. This research compared standard procedures documented in 1972 and those currently practiced for finding moisture content by oven drying, and quantified the variability. Seed cotton from four modern cultivars (ranging from 9.4% to 36.8% foreign matter), lint, and cottonseed were brought from dry conditions, blended, and then stored for more than 30 days in a controlled environment (21°C, 65% RH) to reach uniform moisture content. Additionally, 150 seed cotton samples were placed in plastic zipper bags and sent by air freight to a distant location and back or stored on-site. Drying baskets (652 cm3) were loaded, in random order, with 25, 35, 50, 71, and 100 g seed cotton or 10, 14, 20, 28, and 40 g lint. Cottonseed was placed in 45 cm3 aluminum cups (10 g) or 800 cm3 aluminum baskets (50 g). Wet weights were determined in the controlled environment. After drying, replicated sets of seed cotton, lint, and cottonseed samples were weighed inside a drying oven and then outside the oven while still hot. Some samples were dried for twice the recommended duration. Sample location in the ovens was tracked. Weighing hot seed cotton samples outside the oven after drying increased apparent moisture content by approximately 0.5% due to air buoyancy; weighing lint samples outside the oven increased apparent moisture content by 1%. Smaller differences in apparent seed cotton moisture content were found when halving or doubling the amount of material in drying baskets or doubling the drying duration. Foreign matter had a minor influence on apparent moisture content. Storage for three days and shipping by air freight in plastic zipper bags did not measurably change the apparent moisture content of seed cotton. Sample location within the drying oven made no difference. Current practices are satisfactory if dry weight location is taken into consideration. Measurement uncertainty has decreased compared to 50 years ago, but the recommended minimum number of samples per treatment was increased slightly for greater statistical power. Keywords: Cotton lint, Cottonseed, Moisture content, Oven drying, Seed cotton.

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The lint yield and fiber quality of cotton produced in the Southern High Plains of the USA have improved over the last decade, renewing interest in finding harvest and ginning practices that better preserve fiber quality. Previous research showed that picker harvesting and roller ginning may better preserve fiber quality, but conventional roller ginning was too slow to be adopted as the primary ginning system used for Upland cotton. Advancements in roller ginning technology have increased the ginning rate per unit width of rotary-knife roller gins to approximately equal that of saw gins. Research has shown that improvements in nep content and fiber length characteristics afforded by conventional roller ginning compared to saw ginning are maintained by the new high-speed roller gins (HSRGs). The objective of this work was to compare the fiber quality, seed quality, ginning rate, and lint turnout of Upland cotton produced in the Southern High Plains, harvested using a picker or a stripper, and ginned using saw or HSRG systems. The findings of this work indicate that the HSRG substantially improved the length characteristics of the Upland cultivars tested regardless of harvest method. Turnout was higher for the HSRG and for picker harvested cotton. Nep content was reduced for picker harvested cotton and the HSRG. The fiber length distribution and nep content improvements from the HSRG system make this fiber more attractive to ring spinning mills that produce high-count yarns for high-value products.