March 14, 1794, is the date on Eli Whitney's original patent document for a spike-tooth cotton gin. According to ARS researcher Ed Hughs, the gin shown here (undated photo) is probably a working model that was re-submitted to the patent office after a fire destroyed the original; it differs from the original only in having saw teeth. Both gin types have the disadvantage of breaking cotton fibers, making them less suited for finer textiles. Gin photo courtesy ARS National Agricultural Library Special Collections. Patent document image courtesy National Archives; for more information visit an Archives website.

On Cotton Gin's 211th Anniversary, World Market Demands Gentler Touch

By Don Comis
March 14, 2005

More American upland cotton can be ginned in the future for the longer fibers demanded by foreign textile industries, thanks to Agricultural Research Service (ARS) scientist Ed Hughs and colleagues.

To extract longer fibers, cotton has to be ginned by a roller gin stand. As they strip out seeds, the rollers leave longer fibers than the saw teeth of the cotton gin patented by Eli Whitney on this day 211 years ago.

The problem is that the roller gin is generally used only for pima cotton, leaving out upland cotton, which accounts for most of the cotton grown in this country. Roller gin stands slow down to a generally uneconomical speed of one bale per hour--or less--with upland cotton. Pima moves through at about 1.5 bales an hour.

With funds from Cotton Incorporated of Cary, N.C., Hughs and colleagues at the ARS Southwestern Cotton Ginning Research Laboratory near Las Cruces, N.M., have found that a few adjustments can speed things up so upland cotton moves through the gin at four to five bales an hour, while pima rolls out at six bales an hour.

Cotton. Click the image for more information about it.

This will give farmers more incentive to boost upland cotton's fiber length to gain a larger share of the world market. This year, the United States is expected to export 14 million bales of its expected production of more than 20 million bales.

As another way of increasing cotton industry options, the ARS ginning team has invented a machine that eliminates the need to use defoliation chemicals on the cotton crop.

For the past two harvests, Hughs' team has been testing a tractor-mounted device that kills cotton leaves with a blast of hot air from propane heaters. Cotton farmers currently remove leaves by spraying with a defoliant before harvest. Either way, the dead leaves fall off, which makes for cleaner harvesting and processing.

In research funded by the Propane Education and Research Council, the team designed the thermal defoliator for organic farmers and farmers around residential areas who can't use chemicals.

ARS is the U.S. Department of Agriculture's chief scientific research agency.