Cotton Classing 101

Danny Martinez, Area Director at the USDA Lubbock, Texas, classing office helped design the new and improved classing technology.

In 1907, a group of cotton representatives from around the globe met to resolve key issues throughout the cotton industry. A resolution was passed that established uniform cotton standards to eliminate price gaps and boost price potential for farmers.

The U.S. Department of Agriculture developed cotton grading standards and began offering classing services.
This began an industry-government relationship that remains strong and viable to this day according to the USDA classing booklet.

This partnership between the government and the USDA cotton classing program is continuing to provide beneficial results for U.S. cotton farmers as well as cotton customers abroad.

Getting Started

The process of classing cotton starts at the gins. Where the cotton fibers are separated from seed, cleaned to remove any residue, and then pressed into 500-pound bales. For a cotton sample to be sent to the classing office, it must be at least 8 ounces. A sample of 4 ounces is taken from each side of the bale by a licensed agent and then identified with a Permanent Bale Identification tag. The total sample is then delivered to the USDA classing facility where licensed agents perform the classification under USDA supervision.

“Just like the gins, we never stop working,” said Danny Martinez, area director for the USDA cotton classing office in Lubbock, Texas.

The Lubbock classing office runs on a 24-hour schedule due to the high volume of cotton being produced in and around this region. This office runs off an average of 70 gins and produces an average of 140 samples per hour.

In 2017, approximately 4 million bales were processed here in the Lubbock classing office, that is almost 25 percent of the U.S. cotton crop.

Once the cotton has arrived at the classing facility, the samples are immediately placed in a moisture-controlled environment. The Lubbock facility is kept at 70 degrees Fahrenheit with 65 percent humidity. Environmental factors can affect the strength of individual fibers and the fiber strength measurements.


Martinez, an industrial engineer, helped design the new machinery in the Lubbock classing office to help class cotton more quickly and efficiently. The new technology has doubled the amount of cotton classed in half the time it took with the old equipment.

This new technology ensures precision and accuracy to meet minimum performance specifications. All equipment is tested annually before each cotton season begins, but Martinez said the technology is calibrated every day at the Lubbock classing office. There is certain cotton set aside for calibration testing.

“We calibrate this new technology daily to ensure the best process when it comes to classing cotton here at the Lubbock, Texas, location,” Martinez said.

Classification Process

In a process commonly called high volume instrument classification, the fiber length, length uniformity, fiber strength, micronaire, color grade, trash and leaf grade are precisely measured.

The fiber length of cotton refers to the average length of the longer half of the fibers. The length is measured by passing a beard of parallel fibers through an optical sensing point. The fiber length is often influenced by extreme weather conditions or nutrient deficiencies, which will result in shorter fibers.

Length uniformity is the ratio between the mean length and the upper-half mean length of the fibers. This number is usually a percent. Because of natural variation in cotton plants, this number will always be less than 100 percent.

Fiber strength is the measurements reported in grams per tex, which is equal to the weight of grams of 1,000 meters of fiber. The strength is measured on the same beard as the length is measured, thus the amount of force required to break the fibers is determined.  Fiber strength is also affected by weather conditions and nutrient deficiencies.


Micronaire is the measure of fiber fineness and matureness. This process requires measuring the air permeability of a constant mass of cotton fibers compressed to a fixed volume.

“Because the micronaire measures were very low in 2017,” Martinez said, “it resulted in a lower grade of cotton.”

Color grade of cotton is determined by the degree of reflectance and yellowness. Reflectance indicates how dull or bright the sample can be, while yellowness determines the degree of pigmentation. The color of cotton can be influenced by rainfall, freezes, insects or fungi. The deterioration of color affects the cotton’s ability to hold dyes or finishes.

Trash is the measure of non-lint materials in cotton, such as leaves or bark from the cotton plant itself. This procedure is performed using a camera to scan the surface of the sample. The percentage of surface area covered by trash particles and the number of particles visible are then calculated.

Leaf grade is the measure of leaf content in the cotton sample which is determined by the trash meter percent area and the particle count. Leaf grade can be influenced by plant variety, harvesting methods and harvesting conditions.

“I can be as precise as possible during harvest,” said Cal Francis, a farmer from Perrin, Texas. “And, I still will see measurable amounts of trash and leaf content in the cotton we produce.”

Once the cotton is classed, the USDA will disseminate the data into two formats: official classification information and statistical information regarding quality, volume and pricing. This information is available to ginners or their authorized agents as computer files or printed documents. The data is then available to subsequent owners of the cotton, such as merchants and manufacturers, which is who the USDA classing offices sell to.

According to those who work at the classing office in Lubbock, Texas, the classification of cotton is a very prestigious process. With as much cotton that comes into the Lubbock classing office, Martinez was not exaggerating when he said they work just like the gins, all the time.

“I would say the classing of cotton helps me be a better farmer,” Francis said. “Because I want a higher grade of cotton, I use better farming and harvesting techniques.”