Test Procedure For Cotton

(1) Very carefully weight the sample of 50 gr (3.24 gm) with a good quality balance.An accuracy of ± 0.1 gr (6 gm) is permissible.Use a balance shielded against air currents, as they can cause erroneous sample weight.
(2) Work the sample into a fluffy mass with the fingers to thoroughly randomize the fibres,eliminating all knotty balls and stringy section of fibre.
(3) Place the sample in the fibre compression chamber.
(4)Insert the fibre compression plunger and look into place by twisting.This compress the sample into a porous fibre plug of 1 in.diameter and 1in. length.
(5) Step on the foot pedal to turn on the air and take the scale reading to the nearest 0.1 scale unite at the point level with the top of the float.
(6) Step on the foot pedal to shut off the air,remove the fibre compression plunger and again step on the foot pedal.The sample will be blown out of the compression chamber.
(7) Before inserting another sample, operate the foot pedal to shut off the air supply.
(8) It is recommended that at two sample be chosen and weight from each test lost.

Interpretation Of The Results:

The use of micronaire values for the indication of variation in maturity within a particular growth hass been discussed carlier.A report on the micronaire test is given by Lord.Lord point out that the micronaire test for raw cotton may be used in conjunction with (1) the fibre weight per centimeter to assess fibre maturity, and (2) the routine maturity test ti estimated intrinsic fibre fineness .
The average fibre weight per centimeter,H has been determined by the usual routine method,and micronaire test is made on the same sample.The maturity ratio, M, of the cotton can be calculated using the equation

Knowing H and M ,the standard fibre weight per centimeter can then be calculate from Hs=H/M.
(2) From immaturity test figure for percentages of normal and dead fibres,the maturity ratio M may be calculated and then combined with the information derived from the micronaire test to give the average fibre weight per centimeter.

Air Flow Instruments

A sample of raw cotton is prepared in the from of a cylindrical plug and its resistance to air flow is determined at two degree of cotton of compression.Two measures of specific surface are obtained,and from them estimates of mean specific surface,mean fibre weight,and maturity are derived.Morton and Radhakrishnan investigated the performance of the Arealometer and their conclusions were as flow:
(1) The Arealometer is a portable and self-contained instrument with which it is possible in about 15 min, to measure the specific surface,the hair weight, and the maturity of a sample of raw cotton.
(2) Foe reason which remain to be more fully investigated, is it not suitable for maturity test on material that has been processed or mechanically handle.
(3) Mean specific surface and mean hair weight are determined with an accuracy that is probably not exceeded by any other method,however laborious.
(4) A geometric measure of maturity is obtained which,through not claimed to be as accurately determined as hair weight and and specific surface,seems to be no less reliable than that obtained by the much more subjective method of deconvolution counts.

The Speeder

This is another American instrument and is designed to measure specific surface quickly.Any weight of sample between 5 and 10 gm may tested.Adjustment weight is not required,there fore an increase in the speed of testing is achieved.

The Port-Ar

A portable instrument testing an 8 gm sample and producing (1) micronaire value,and (2) equivalent fibre thickness.The latter is defined as

H=2000/A
where
H= equivalent fibre thickness,and
A= Specific surface in square millimeters per cubic millimeter.

The Maturity Of Cotton Fibre

The maturity of ratio concerns the development of the cell wall.The perimeter of the cotton fibre is least affected by environment and most by heredity,but cell wall thickening is highly sensitive to growing condition.Even when cotton is grown under favorable condition a small proportion of the fibre will be under development or immature,but adverse weather,poor soil,plant disease,and pests,will increase the proportion of immature fibre and lead to trouble in processing.Immaturity in tje truft tends to remain the patches and immature fibre tends to associate even through to the yarn stage.Small patches or crops can be affected and the Chances of maturity variation are great in any symbol or bale of cotton.

One of the main trouble caused by the presence of these thin walled immature fibres is nepping.Apart from natural cause like fragments of seed pod attached to a fibre,nepping is CREATED during processing,starting at the gin.Where rubbing between surfaces occurs, that is during carding,minute knots of tangled fibre are caused and flabby immature fibre are most prone to this nepping effect.When fine cotton are being processed the danger of nepping is even more acute,since even mature fine cottons can be nepped by faulty processing.I addition,the neps so formed are uaually more prominent because of their size relative to the diameter of the finer yarn.

Immaturity also affect the shade after dyeing.As the response of the primary wall to certain classes of dyes is less intense,thinner the secondary wall the lighter the shade.Fine cotton tends to be lighter in shade than coarse cotton.This is only a partial explanation of shade difference.The color component reaching the eye from dyed fibre is mainly composed of rays of light reflected from internal surface.If the walls are thinner there will be greater possible number reflecting surfaces per unit mass of cellulose and,consequently,a greater amount of light emerging after passing through only a small amount of stained material.The appartment shade is there for lighter.
With two deliveries of weft spun from cotton different maturity,weft bars are possibility.Neps will show uo as speaks inthe dyed cloth.

In order to assess the quality of cotton with respect to maturity and its effect on ends down,yarn strength,dyeing trouble,and so on,some method of measurement is required.The degree of cell wall thickening may be expressed as the ratio of the accrual cross-sectional area of the wall to the area of the circle with the same perimeter.

Direct measurement of this ratio is not a practicable routine test and is not normally done.An indirect method which has been in use for a number of years is the cotton fibre immaturity count.A convenient time at which to make this test is after a sorter diagram has been prepared for the measurement of the fibre length characteristics and fibre weight per centimeter.After the fibre weight has been determined,five tufts of cotton are left on the velentpad. Each tuft is laid on a microscope slide.the fibres parallel but separated,and a cover slip put over the middle.
The fibre are then irrigated with a small amount of 18 per cent caustic soda solution which has the effect of swelling them.The presence or absence convolution is then observed,preferably by means of a projection microscope.This enables the fibre to be classified into three groups.
1.Normal Fibres.
2.Thin-walled Fibres.
3.Dead Fibres.
Mature fibres with a well-developed cell wall and pronounced convolution in the raw state become eode like after swelling.These rod-like fibres are closed as 'Normall' Dead fibre appear ribbonlike even after swelling.Thin walled fibres are those lying between the other two classes.Borderline cases may be judged from the thickness of the cell wall relative to the total width of the 'ribbon'.

The Counting And Classification Is Done In Three Stages:

1.All the fibre are counted.
2.The rod-like fibre are counted.N
3.The dead fibre are counted.D
Classification and counting is carried out for each the fibre groups,the number converted to percentage,and the means calculated.The result of the test is then expressed as N-D,that is 64-14 would mean that 64 per cent of the fibres counted were classed as normal and 14 per cent classed as dead;therefore,by subtraction,22 per cent would be classed as thin-wall fibres.
It is a desirable to express the result as a single figure which would give the actual maturity observed as a fraction of some suitably chosen standard maturity.From a sample of 100 fibres it would be ABNORMAL to find that all the fibres could be classed as 'normal' fibres. A standard was chosen which was of fully matured cotton crops grown under the best possible conditions.The standard chosen was:
N-D=67-7=60
It is also desirable that the result should be propotional to the geometrical measure of cell wall thickening,the 'degree of thickening'.

Maturity Ratio:

The maturity ratio to be derived from these conclusions is the ratio which express the actual fibre weight per centimeter, H,in relation to a standard fibre weight per centimeter Hs.

By definition,the standard fibre weight per centimeter,Hs, is that which the fibre would have if it were fully matured in the arbitary sense of having an
N-D.

The link between immaturity count and fibre weight:

Peirce and lord found N-D and H for several pure strains of cotton and within each series only the maturity varied.A linear relationship was found betwee H and N-D:

Cotton Fibre Quality

The characteristics of cotton which are of the importance in the assessment of its quality include fineness,length,maturity,uniformity,and grade.All but the latter term have been considered already but the term 'grade' requires explanation.One of the main function of the men who handle the cotton between grower and spinner is to make available to the spinner a range of different types of cotton from which he may choose a type suitable for the purpose in view,e.g.hosiery yarn,fine yarn for shirting,etc.When the type of cotton has been decided upon,the spinner requires a certain degree of uniformity and continuity in the quality of the raw material delivered to his mill.Since cotton quality varies from year to year,field ti field,and bale to bale,some system of classification or grading must be used to ensure that the spinner receive his cotton in smoothly running lots,otherwise the problem continual readjustment and setting of the processing machinery will become great indeed.
When grading itself is considered we again meet variation,this time in the method used in grading and even difference in the terminology. Differences between centers separated by great distances can e understood to some extent,but we find that differences in grading cotton exist between markets relatively close together,e.g.Egypt and Sudan.It is not intended to discuss all the grading systems but to illustrate two which employ different criteria of evaluation.

American Cotton Grading:

The grading of American Upland cotton is based upon three main characteristics: color,trash content or foreign matter,and preparation.It is important to note that staple length is not one of the three.The color may be referred to as extra white,white,spotted,tinged,and yellow stained,in decreasing orderof merit.The variety,weather,soil,picking efficiency,and so on govern the color.

Foreign matter or trash consists of such materials as broken leaf and pod,sand and dirt.Some types are relatively easy to remove during processing.e.g.sand,but cute seeds with fibre still adhering to them are troublesome.Increased use of mechanical pickers leads to an increase in trash since the machine cannot exercise card or discriminate,as can a human cotton pickers.

The efficiency of ginning process is reflected in the assessment of the preparation.Poor ginning may result in damage fibre,neps,and stringy looking lint.Good preparation is denoted by an 'A' credit,poor preparation a 'C' with an intermediate category 'B'.
The United State Department of Agriculture has a series of standards for cotton grade.In 1941,thirty-two grades were officially recognized but these are based on eight on main grades:

Serial No	Cotton Grading
1 2 3 4 5 6 7 8	Middling fair Strict good middling Good middling Middling Strict low middling Low middling Strict good ordinary Good ordinary

It is interested to note that the grade 'Middling' is used as a basis for pricing of American cotton.
It is pointed out by lord that,even when suitable type standards have been inaugurated there are still serious problem.Type standards require continual replacement if their character is likely to change over a period of time.Moreover,interpretation of type standards in everyday practices by different people at different place also make calls personal skill.

Sudan-Egyptian Cotton Grading:

In the cotton growing region of the Gezira plain,the cotton is grade into six full grades.1 to 6 in descending order of quality,with half-grades denoted by 'X' a symbol foe 'Extra'.The classifier includes an assessment of the staple length in his judgment of the cotton,as well as

fineness,appearance,color,and trash content.The initial grading is made on the cotton before it is ginned and may be regraded at a second examination after it has reached the shipping point of port Sudan.The effect of the inclusion of a length assessment and the reduction of the importance of trash content as compared with American grading practice will be appreciated by a study of the graphs in figures.The reader is recommended to expand his knowledge of cottons and cotton quality by further study of the literature,in particular the papers by Lord on the production and characteristics of the world's cotton crops.

The Measurement of trash content

In the previous section,reference to trash content have been made.The machine used for its determination is an instrument developed by the British cotton Industry Research Association and made by Platts.The details of the analyzer are given belloand have been condensed from the makers describe booklet.

The machine operates on the principal of 'buoyancy separation' by the use of air current.The separation of cotton and the trash takes place as the two travel with the air stream through the settling chamber,the heavy trash particles falling almost straight down to the trash tray.On the other hand,as the single cotton hairs are entirely controlled by the air stream they are carried along with it and out of the chamber.The light trash particles tend to fall, but they are taken some way by the air stream.By correct adjustment of the air currents they ultimately fall into the trash tray at a point further forward than the heavier particles.The paths of the various particles are indicated by the dotted lines.

Wool Fibre Quality

When the wool sorter classifies wool he rapidly assesses such factors as fibre fineness,crimp,length,scalines,handle,and lustre,but the most important characteristic which is judges is fineness.

Fineness

Although the mean fibre diameter is an important component quality,an indirect method of expressing the fibre fineness is used.Other things being equal,a finer fibre can be spun into a finer yarn.This being so,the original basis for assessing fineness was to estimate the finest yarn that the wool sample could produce.

For example,a sample of wool could be classed as 58s, the inference being that the spinner could make a 58s worsted yarn from it.The developments in spinning techniques have enable the spinner to produce finer counts than the quality number would suggest but,nevertheless,the original standards have been adhered to.The three main class of wool are Merino,sometime called Botany,with quality numbers 60s to 100s,36s to 58s and Carpet,up to 36s.
The American standard links the measurement of wool fibre diameter by the projection microscope and the grade.

Crimp

A feature of the wool fibre is its 'crimp'or waviness.

Average diameter µ (min.)	Average diameter µ (max.)	Grade
17.7 19.2 20.6 22.1 23.5 25.0 26.5 27.9 28.4 31.0 32.7 34.4 36.2 38.1	19.1 21.5 22.0 23.4 24.9 26.4 27.8 29.3 30.9 32.6 34.3 36.1 38.0 40.2	80s 70s 64s 62s 60s 58s 56s 54s 50s 48s 46s 44s 40s 36s

Researches has shown that some form of relationship exist between the crimps per inch and the fibre fineness, the finer the fibre the greater the number of crimps per inch.The wool sorters judgment of fineness and his subsequent estimate of the quality number is probably influenced considerably by this knowledge.

Length

When the length of wool fibres is considered it is found that in the mai sorter wools are fine and the longer wools coarse,a reversal of the order for cotton fibres.For worsted yarns,fibres which are long,fine,and uniform in length are disirable,and because in most of cases a combing process is used in their preparation,wools suitable for worsted yarns are termed 'combing' wools.For woollen yarn where a softly handle is wanted and where the fibres are carded,the shorter wools are chosen and referred to as 'clothing' wools

Ellipticity

The cross-section of wool fibres are nearly circular,but have varying degrees a combingof ellipticity, the amount being expressed as the 'contour ratio' the ratio between the major and minor axes of the fibre contour.Some authorities are of the opinion that the nearer this ratio is to unity,i.e. the more circilar the fibres,the better the wool will spin.
Wool quality is big subject and these notes are,of necessity,brief.

Flax Fibre Quality

Flax Quality

The author is indebted to the Linen Industry Research Association for the note on the grading of flax which follow

Flax Grading

The value of parcel of flax to the spinner depended on the quality of the yarn which may be spun and on the quantity of yarn obtained.When grading,the grader must attempt assess the various characteristics that are related to these to factors and to integrate them into a single value or grade.
The spinning quality depended mainly on the fineness and the strength of the fibre strands and lesser degree, on their length.Flax with fine strands is compact and is of better quality than flax with coarse strands and low apparent density colour and uniformity are also taken into account.The quantity of yarn obtained from a lot of flax depends on the yield i heckling.Heckling yield depends on a number of factors.
(1).The handling of the flax:i.e. freedom from knots and tangles.
(2).Cleanliness: i.e.the amount dust remaining after scutching.
(3).Fibre length:Especially the amount of short fibre present.
(4).Strength and fineness of the fibre:The flax markets in different parts of the world each has its own systems of marking the various qualities.

Jute Fibre Quality

The annual production of jute is second only to cotton and two main growing areas are Bangladesh and India. A small crops is grown in Brazil but is for home consumption. Grade designation for jute are rather complicated because growers and exporters use certain system and manufacturers use other.

The two botanical species of jute CORCHORUS CAPSULARIS and CORCHORUS OLITORIUS,their more common names while jute and Tossa Jute

Grading is carried out in two stages, one close to its source and the second at the bailing station. The grade bales are tightly pressed,weight 400 lb,and valled 'pukka'bales.Quality is assessed by consideration of such fibre properties as texture,colour, lustre,length cleanliness.

The pukka bales are graded to indicate Their Make up:
TOP sound fibre of good colour for the district and containing not more than 25 percent cent 'cutting' MIDDLE .Sound fibre are averages colour and containing not more than 25 percent cuttings.