HVIColorGradeOtherCottonProgramIssues

8/8/2019 HVIColorGradeOtherCottonProgramIssues

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HVI COLOR GRADE AND OTHER COTTON PROGRAM ISSUES

Darryl W. Earnest

Assistant Associate Deputy Administrator USDA, AMS, Cotton Program

Washington, DC

Abstract

The USDA, Agricultural Marketing Service, Cotton Program is currently working to meet the

changing needs and expectations of the cotton industry through advancements in its cotton

classification procedures. This report will discuss four of the primary areas undergoing changes:

1) adopting High Volume Instrument (HVI) color as the official color grade; 2) changing the

standards and classification procedures for American Pima cotton; 3) evaluating improved

measurements for short fiber content; and 4) implementing an automated classing system. Thesedramatic changes are expected to greatly enhance the cotton classification services currently

provided to the industry by the Cotton Program.

HVI Color Grade as Official Color Grade

The most notable change being implemented by the Cotton Program this year is the transition to

using the HVI color grade as the official grade for color. During the 1998 classing season, the

Cotton Program conducted a pilot project in conjunction with the National Cotton Council Quality

Task Force Committee with the goal in mind of improving the HVI color grade determination.

The objective of the pilot project was to make the HVI color grades closely match the Universal

Cotton Standards used by classers to determine official color grade. In order to accomplish this, an

adjustment was made to the conversion of the reflectance measurement, "Rd", and the yellowness

measurement, "+b" to match the Universal Cotton Standards. The locations of the 1986 Universal

Standards for Color plotted on the Nickerson-Hunter color diagram provided the basis for this

adjustment. This color diagram has served as the reference for all standards produced since 1986.

Once this adjustment was made, the Cotton Program evaluated the overall impact by analyzing all

of the white and light spotted grades assigned during the 1998 and 1999 classing seasons. Results

from both years revealed a color grade assignment that closely matched the Universal Cotton

Standards for color.

Data analyzed from the 1999 season revealed that 87% of the classer color grades and 90% of the

HVI color grades were classified as white. In addition, 12% of the classer grades and 10% of the

HVI grades were classified as light-spotted. The reproducibility for both methods remained


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consistent at approximately 74% - 75% for both the classer and the HVI color grades.

As a result of continued improvements in technology and calibration techniques, the

reproducibility results for Rd and +b have improved to all-time highs in 1998 and 1999. In 1998,

the reproducibilities were 93% for both Rd and +b. In 1999, the reproducibilities were again

consistently high with 92% for Rd and 93% for +b. The tolerances for these measurements are +/-

I unit for Rd and +/-0.5 unit for +b. Given the advancements made in color measurement and the

high degree of performance exhibited over the past few years, the Cotton Program is very

confident that the HVI color grade is suitable to be the official color grade. As a result of the study

and the results shown by the Cotton Program, the National Cotton Council Quality Task Force

Committee made a recommendation earlier this year to adopt the HVI color grade as the official

color grade. The National Cotton Council's Board of Directors voted in favor of the

recommendation. The cotton industry agreed to accept the decision and there were no negative

responses received regarding the issue. As a result, the HVI color grade will be implemented as

the official color grade effective July 1, 2000.

Proposed Changes for American Pima Standards and Classification

The classification for American Pima cotton has remained unchanged since 1986. However, the

Cotton Program has received comments from the industry requesting a change in the standards

and classification procedures to reflect a separation of color grade and leaf grade. The current

classification system is a composite system based primarily on appearance with six physical

standards and one descriptive standard.

On September 15, 1999 the Cotton Program received a formal request from the Supima

Association of America to amend the 'method for grading American Pima cotton to allow for

separation of color and leaf content determinations. The various segments of the cotton industry

affected by the separation of the Pima grade have indicated their support for the move and have

requested that the Cotton Program progress forward with this new system.

Under the proposed American Pima classification system, LJSDA classers will determine a color

grade and a leaf grade on all samples classed. Separate standards for color grade and leaf grade


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will be established and utilized for comparison by the classers. The Cotton Program's

Standardization and Quality Assurance Branch will establish color grades and leaf grades for

American Pima cotton from the current composite grade standards. The revised color grade

standards will continue to consist of six physical standards, grade 01 through 06, and one

descriptive standard, grade 07 or below grade. The proposed physical standards will not be

changed from the current grade standards for color. Leaf grade standards will be designated as

Leaf grade No. I through Leaf grade No. 7 with Leaf grade No. 7 being below grade. Bark will no

longer be part of the physical standards and will be removed from grades 04, 05, and 06.

A set of proposed Pima standards reflecting the new guidelines was prepared and displayed at

several locations across the Pima producing territories of the U.S. Industry was encouraged to

inspect the standards and give comments regarding the proposed changes. A special Pima

standards conference will be conducted in June 2000 in conjunction with the annual Upland

conference held in Memphis, Tennessee. At this time, industry will review the proposed standards

and make final comments and approval. Once approval is received, the Cotton Program will

proceed with its plans to implement the new standards effective July 1, 2001 .

Under the proposed American Pima classification system, an official color grade and an official

leaf grade will be assigned to each sample classed. The color grade and leaf grade determinations

will be assigned by USDA classers through visual comparisons of samples to the appropriate

physical standard for color or leaf. Since an official color grade and leaf grade will be assigned to

each sample, the current procedure that allows for averaging offactors of grade will be eliminated.

The presence of bark in American Pima cotton will be considered as extraneous matter under the

proposed classification system. The presence of extraneous matter, including bark, and other

special conditions will be identified on the official classification record. American Pima cotton

will not be reduced in grade due to the presence of extraneous matter.

HVI Short Fiber Content

The Cotton Program has been evaluating two methods for determining short fiber content on the

HVI. The first method utilizes a short fiber index algorithm, developed by Zeilweger Uster, to

derive a fibrogram-based short fiber index. This method has been under evaluation by the Cotton


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Program for the past three classing seasons. The accuracy of this measurement was improved

following the addition of a cotton calibration routine after the first classing season. Over the past

two classing seasons, overall average between instrument reproducibility (for cottons from all

U.S. growth areas), with a tolerance of 1.0%, has remained constant at approximately 58%.

However, the range of short fiber reproducibilities over different growth areas varied from 46% to

69% (1999 crop). Cottons containing high short fiber content consistently have lower

reproducibilities while cottons with low short fiber content tend to have higher reproducibilities.

The second method being evaluated utilizes an equation to derive short fiber index from the HVI

measurements of length and length uniformity index. The resulting short fiber estimate is referred

to as L/UI short fiber content. The equation, which was developed in 1998, was designed to

predict the short fiber measurement provided by the HVI short fiber index algorithm. A thorough

evaluation of L/UI short fiber content was conducted during the 1999 classing season. Although

complete analysis has not been concluded, preliminary data are very encouraging. Overall average

between instrument reproducibility (for cottons from all U.S. growth areas), with a tolerance of

1.0%, was approximately 74%. The range of short fiber reproducibilities over the different growth

areas varied from 62% to 82%

Both HVI short fiber measurement methods produce a very similar short fiber measurement level.

The main difference between the two measurement methods is in variability, which is reflected in

the reproducibility differences. The ultimate test for any new measurement is in its ability to

provide information to the textile mill for optimizing processing performance. Plans are now in

place to conduct such a test on each of the short fiber measurement methods in a mill-processing

environment.

Automated Classing System (ACS)

The USDA, AMS, Cotton Program is entering into an new arena of HVI classification with the

forthcoming implementation of a new automated classing system (ACS) developed and

manufactured by Zeilweger Uster. The new system is scheduled for implementation into the

Cotton Program's Memphis, Tennessee classing office in August 2000. The new system will be

the only one of its kind in existence and will introduce a fully automated method of HVI

classification.


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The AC'S consists of more than just High Volume Instruments. It incorporates an entire HVI

classing operation into a fully automated system that will require no HVI operators. An integrated

conveyor system equipped with logic stations and control technology will guide cotton samples

throughout the testing process. The system will be monitored by a main control station and will

also be connected to the Cotton Program's Tandem computer network.

Cotton samples will continue to be conditioned for HVI testing using Rapid Conditioning Units

that draw conditioned air (70 degrees F +/- I degree and 65 % relative humidity +/- 2%) down

through them until they reach the required moisture range of 6.75% - 8.25% prior to HVI testing.

Once conditioned, the samples will be classified for leaf and extraneous matter by classers who

will then "load" them into specially designed cassettes. Each cassette will automatically be fed

into the integrated conveyor system from the loading station and transported to a randomly

selected HVI station. The sample will receive quality measurements for length, strength,

micronaire, length uniformity, color Rd, color +b, and trash. Once testing is completed, the sample

will be transported out of the HVI and to a decision station where the computer system will

determine if the sample can be discarded or requires re-test or special handling. Once this decision

is made, the sample is either automatically discarded into a loose cotton removal system, or re-

routed to the appropriate area. The empty cassette is then returned to the flow and the process

begins again.

If successful, the ACS will revolutionize the way that the Cotton Program currently operates. The

new system is a major advancement that will increase operational efficiency and provide a more

accurate method of cotton classification. The Cotton Program is eager to implement this innovative

system and move toward an improved methodology.


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Conclusions

The mission of the LJSDA, AMS, Cotton Program is to promote the orderly and efficient

marketing of cotton by preparing, distributing, and encouraging the use of universal cotton

classification standards, and by providing cotton classification and market news that meet the

needs and expectations of the cotton industry. The four areas discussed above are new and

innovative ways in which the Cotton Program is meeting the needs of the cotton industry and

fulfilling its mission. Adopting HVI color as the official color grade, modifying the current Pima

standards and classification system, developing and evaluating new methods for measuring short

fiber content, and implementing a fully automated classing system are all steps toward improving

the process of cotton classification. These steps, in turn, will help the Cotton Program succeed in

providing the highest quality services possible to its customers.

HVIColorGradeOtherCottonProgramIssues

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