Some Experience In Cotton Grade Examination

The cotton grade examination is to judge cotton grade according to the visual quality of hand feeling according to the standard of cotton sample in combination with the grade condition in accordance with the prescribed light conditions.

Grade examination is an important quality in cotton inspection.

Grade examination seems simple. Actually, it is not easy to grasp it well.

The results of grade examination are closely related to light conditions, operation methods and density of cotton samples. Therefore, we must conscientiously and carefully, repeatedly fumble in our work, practice repeatedly and accumulate rich experience, so as to ensure the accuracy of the inspection results.

According to my own practice of cotton grade examination for many years, I will talk about how to do well the cotton grade inspection work.

Deep understanding, comprehensive and accurate grasp of the three conditions of grade

1. maturity.

Maturity refers to the degree of accumulation of cellulose in cotton fibers. It is a reflection of the intrinsic quality of cotton fibers and a key indicator for determining the use value of cotton.

Sensory testing of cotton fiber maturity is only a rough qualitative judgement and can not be quantified. The maturity of cotton is usually determined by hand grasping, hand pulling and visual inspection.

Through visual observation, hand pulling, hand grasping and kneading, feel the gloss, elasticity and strength of cotton fibers and so on, indicating maturity.

The higher the quality of the cotton, the higher the quality index, the better the 20-30g grip and the tighter grip. The longer the time is, the stronger the pressure and swelling force of the cotton ball will be, the stronger the hand feel will be, and the feeling of holding can not hold. Or the hand touch feeling fiber is more delicate, soft and smooth.

But it is worth noting that the same type of cotton lint at the same time and cotton at the same time are not as good as the handle of the samples of cotton covered cotton pads. Besides, when testing, do not think that the cotton with high moisture content is considered to be of poor maturity, and do not mistake the cotton seeds with low moisture as good maturity and avoid misjudgement.

2. color characteristics.

Color characteristics refer to the color and gloss of cotton fibers, and the inherent quality of cotton fibers in appearance.

When testing the color of cotton, it must conform to the national standard.

3. quality of rolling mill.

The quality of rolling mill is a reflection of the influence of cotton gin technology on cotton quality, and whether the technology of rolling is reasonable or not reflects the quality of rolling mill.

The following are the following methods: first, look at the number of "defects" in the cotton roller "Huang Gen" and the sawtooth cotton, and the quality of the rolling mill is poor. The two is to see the appearance of lint. If the surface of the lint is uniform, straight, smooth and clear, and the phenomenon of fiber entanglement is not seen, the quality of the rolling mill is excellent. If the fiber is rough and rough, and the yarn rope NEP is mostly the rolling difference; three, if the fiber is broken, it is generally used to measure the short fiber content of 13mm and below to evaluate the situation of the broken fiber. The national standard of cotton has requirements for the quality of 1-5 grades of roller cotton and sawtooth cotton. It requires that the yellow root, gross rate and defect be controlled within the prescribed target.

In a word, in order to grasp the three conditions of grade, we should not be isolated and rigid, so they should be combined organically and comprehensively. In this way, the grade of cotton can be reflected objectively and realistically.

Understanding the characteristics of cotton grades at different growth stages

1. characteristics of early cotton.

The quality and quality of cotton grades are affected by many factors. Generally speaking, during the growth and development of cotton fiber, there is no sufficient thickening period in the growth period of cotton fiber because of the unfavorable climatic conditions, that is, the thickening period of cell walls is insufficient, the coefficient of daily rotation is too low, and the maturity is poor.

Because of early cotton growth at the roots of cotton plants, lack of light, the growth of cotton generally poor maturity, hand broken head neat, indicating poor strength, cotton fiber color is poor, white and lustrous.

Generally, the cotton in early or early stages of drought, or cotton with early diseases and insect pests, is short in length, stiff in size, poor in maturity, and white in color.

Therefore, most of the ranks are below grade four, and a few good ones can be classified as three.

2. medium term cotton characteristics.

During the growth and development of cotton in the middle period, the cotton fiber grows in the upper part of the cotton plant because of the better climatic conditions, and the cotton fiber grows thicker, and the daily wheel coefficient is complete. The cotton fiber grows well and has a good maturity.

Grasp cotton with your hands and get good elasticity. Breaking fiber is strong, white and bright or mercerized, mostly medium and high grade flowers.

3. cotton characteristics after (late).

In late cotton harvest, frosted cotton was caused by sudden drop in temperature due to a sudden drop in temperature.

Frost cotton can be divided into light frost cotton and heavy frost cotton.

Light frost cotton is white, dark or heavily stained, but most of the fibers are well matured and contain a small amount of yellow dots. Heavy frost cotton is lighter, and the background is generally yellowish and dark red.

Some of the frost cotton maturity, strength, fineness, appearance can reach three, but the color is yellow than the four or five grade standard cotton, frost cotton has been stipulated in the standard, the highest level is four.

For light frost cotton or slightly heavier frost cotton, the inner quality can be up to three grade, but the color to the top or near the five grade can be classified as four grade cotton. The heavy and especially heavy frost cotton can be set to five grade. The late maturity varieties of frost cotton, maturity and poor strength, have bad hair, heavy frost, especially heavy can be set below six.

Pay attention to the grasp of several special cotton grades

1. test of rain and rust cotton.

During the cotton picking process, because of the weather reason, the rain was too long and the time was too long to produce rain and rust cotton.

2. for cotton with larger or larger moisture.

After rain, cloudy day and morning dew picked cotton, the cotton produced and processed in winter, snow and ten or twenty degrees below zero, because of the high moisture absorption of cotton, when testing, due to large moisture, elastic feel is small, silk, neps obvious, surface appearance is also ugly.

It is often possible to set a lower grade, but after balancing, placing and expanding, the moisture content is small, the resilience is restored, and the sash and neps are loose.

3. cotton inspection has not been cleaned by seed cotton cleaning machine and lint cleaner.

PI Qing cotton is a lint that has been cleaned by the saw toothed cotton gin and has been cleaned by lint cleaner.

Compared with lint cotton without lint cleaning machine, impurities, silk and key dyeing are significantly reduced, fiber is smooth and color is good. However, the fine impurities, defects and neps of leather and cotton are broken. Some of the fibers are broken during cleaning, some fibers are damaged, and the content of staple fibers increases.

PI Qing cotton is better than the cotton lint that has not been cleaned in appearance and color. That is to say, "Xiang Xiang" has been improved, but it has not improved the internal quality of cotton fiber, but is not as good as the latter in terms of use value.

Therefore, when testing cotton that is not cleaned, it should be considered from the perspective of textile use value, and the quality should not be excessive.