Determination of Cotton Color Grade

1. COTTON COLOR GRADE
MD. MAZBAH UDDIN
BANGLADESHUNIVERSITY OF TEXTILES
YARN ENGINEERINGDEPARTMET
BATCH 08

2. HVI: COLOR GRADE:
The USTER® HVI 1000 measures themostimportant cotton fiber properties for
cotton classing purposes, and high-throughputrequirements for spinning mills.
These are length, uniformity, shortfiber index, micronaire, maturity index,
strength, elongation, color and trash, and moisturecontent.
Reflectance (Rd)
This value expresses the whiteness of the light that is reflected by the cotton
fibers. Itcorresponds to the reflectance (Rd) represented in the Nickerson/Hunter
color chart. Itis used in conjunction with the yellowness (+b) to determine the
instrument-measured color gradeof the cotton.
Yellowness (+b)
This value expresses the yellowness of the light that is reflected by the cotton
fibers. The yellowness (+b) of the sample is determined by using a yellow filter. It
corresponds to the +b value represented in the Nickerson/Hunter color chart. The
yellowness is used in conjunction with the reflectance (Rd) value to determine the
instrument-measured color gradeof the cotton.

3. Color Grade:
The color grade is a measureof the reflectance (Rd) and the yellowness (+b) of
cotton fibers. The determination of the color gradeis based on the Nickerson-
Hunter cotton colorimeter diagramfor Upland cotton.
The color code can be determined at the point where the reflectance Rd and the
yellowness +b intersect on the Nickerson-Hunter scale. There exists a relationship
between the grades used by certified classers and the Nickerson-Hunter scale
which is shown in Table and Figure below:

4. Example: The reflectance Rd equals 66, the yellowness equals 11.4. The
classification of the Nickerson-Hunter scalewill lead to the following result: the
two lines intersected in area 43, which is equivalent to strict low middling and the
spotted.
Color Grade(C Grade)
Itis the combination of Rd and +b; representing official USDA Upland Grade
Standards.

6. Leaf/Trash Grade(Tr Grade)
Leaf or trash gradedescribes the leaf or trash (seed-coatfragment, grass, bark
etc.) content in the cotton. This gradeis a visual estimate of the amount of cotton
plant leaf or trash particles in the cotton. Purity as regards the presenceof foreign
matter (wastesuch as leaves or earth) is of the utmost importance. There are
seven official leaf grades for American upland cotton designated as "Leaf Grade 1"
through "Leaf Grade7". They are all represented by official physicalstandards in
the custody of the USDA. In addition, there is a descriptive "Below Leaf Grade
Cotton" designation for American upland cotton that is lower in leaf gradethan
Leaf Grade 7. Leaf content is affected by plant variety, harvesting methods, and
harvesting conditions. The amount of leaf remaining in the lint after ginning
depends on the amount resentin the cotton prior to ginning, and on the type and
amount of cleaning and drying equipment used. Even with the mostcareful
harvesting and ginning methods, a small amountof leaf remains in the cotton lint.
Fromthe manufacturing standpoint, leaf content is all waste, and there is a cost
factor associated with its removal. Also, small particles cannotalways be
successfully removed and thoseparticles may detract fromthe quality of the
finished product.
XY-Z; X= classers reflectancegrade, Y=classers yellowness grade, Z=leaf grade.
Example: 122, meaning Good middling, light spotted and leaf grade 2 (<=.2)

7. Spinning Consistency Index(SCI)
The Spinning Consistency Indexis a coefficient that is calculated by means of
various quality characteristics by a multiple regression analysis. TheSCI used is
calculated with the original formula provided by USTER. The main benefit of the
SCI is a simplified selection of bales for a predetermined blend of fibers as well as
the long-termcheck of the raw material blend. This index can be used to simplify
the category systemused in the cotton warehouse. In general, the higher the
index, the higher the yarn strength and the better the overall fiber spin ability.
The equation for the SCI valueis:
SCI = -414.67 +2.9 x Strength – 9.32 xMicronaire + 49.17 x Length (“) + 4.74 x
Uniformity + 0.65 xRd + 0.36 x +b
Based on the customer’s experience, the individual contributions of each fiber
property can be adjusted to specific mill applications.
ICC=-414.67 +2.9 x Strength – 9.32 xMicronaire + 49.17 x Length (“) + 8.61 x
Uniformity + 0.65 xRd + 0.36 x +b