Relationship between wool fineness and crimp frequency

relationship between wool fineness and crimp frequency

frequency affects the processing of raw wool and the handle of finished cloth are understand the visual relationship of the crimps per centimeter of the sheep's wool further evidence that crimp count does not accurately predict fineness. The mean fibre diameter of wool of Merino, rams, measured as two- Merino studs chose stock for wool fineness on the basis of crimp frequency. With' the N.S.W. Sheepbreeders' Association did not differ significantly from the mean of. Article (PDF Available) in International Journal of Sheep and Wool Science The crimp frequency versus fibre curvature relationship for cashmere was quite strong . Fibre fineness and resistance to compression (Rc) are the most important.

C of V - is the coefficient of variation which indicates the micron "spread" relative to the average micron. It allows the "spread" of micron of sheep of different average micron to be compared. Uniformity of fibre diameter is the basis of wool quality and is characterised by well defined and evenly spaced crimps better known and "style".

C of V can also be used as an efficient indicator of staple strength. Low C of V of fibre diameter, lead to a high staple strength. Coarse Edge - indicates the proportion of comparatively coarse fibres which are not described by the standard deviation or coefficient of variation. It measures the "tail" of the FD Histogram. These fibres disrupt the internal staple structure and are the framework for feathery tips.

relationship between wool fineness and crimp frequency

In severe cases, they can be pre-emptive of the future increase in the average micron of that sheep. The coarse edge qualifies and fine - tunes the C of V assessment. This is helpful in determining those animals with a left hand shift on their histograms.

Spinning Fineness - is a numeric calculation that relates C of V to the actual micron in terms of spinning ability. The spinning qualities of wool are enhanced by a low coefficient of variation, which enables the wool to be processed at standards less than the given micron. Yield measures the "true wool" by eliminating the grease, swint, wax and dirt.

Understanding Wool Test Results

Fibre Curvature - is a new approach to measuring "crimp" in wool, and recent evidence shows that curvature is probably the third most important fibre specification after diameter and length.

What use is curvature? Curvature relates strongly to staple crimp characteristics, particularly crimp frequency - for as frequency increases, the fibres are increasingly curved. But curvature is not the same as character staple crimp definitionwhich is a measure of how well aligned fibres are.

relationship between wool fineness and crimp frequency

Fibre alignment and thus staple crimp definition does however relate to the CV of curvature, since it is physically hard to align fibres differing in curvature. Figure 1 illustrates these points: Recent scientific evidence confirms that wool fibre curvature influences processing efficiency, particularly during topmaking and spinning operations, yarn thickness and evenness and fabric thickness, handle and quality.

Wools of high crimp curvature tend to show increased fibre breakage during carding, relative to wools of low crimp curvature. Wools of poor crimp definition high CV of curvature tend to show increased fibre breakage in processing, in comparison to wools of good character. Today buyers are making more and more use of the actual yield, that is a laboratory determined yield which is part and parcel of objective measurement implemented in July Raw wool consists of pure wool keratin and natural impurities such as wool wax grease and suint as well as acquired impurities such as vegetable matter, dirt, dust and sand.

These different impurities may vary in different proportions and thus influence the clean yield of the wool. The yolk wool wax and suint is, however, considered necessary to coat and also to bind the fibres together into staples preventing the fibres from falling open and being damaged deeper into the staple by the sun.

Wools deficient in yolk normally also feel harsh. An increase in the iodine number indicative of a fluid wool wax was considered of more value. This increase in wool wax consequently caused a sharp decline in the yield percentage of the wool of rams. Generally, the weight of vegetable matter is small and has little influence on yield.

The greater percentage of vegetable matter is removed mechanically in the carding and combing processes.

Fleece Testing Reporting Functions

In considering clean values of wools which in the greasy form contain vegetable material, account must be taken of the additional loss of fibres which cling to vegetable material, such as burr, during carding and also the additional fibre breakage when beating the burr from the wool. Wool that cannot be cleansed mechanically has to be carbonised. In the carbonising process the wool is treated with diluted sulphuric acid. Wool treated in this way becomes inferior because of the damage sustained by the fibres.

The presence of vegetable matter is a problem in the processing of wool and high degrees of contamination with burr and fine grass seed should be avoided as far as possible. Dirt, dust and sand - anyone or all together - varies most of all foreign matter in the fleece. LENGTH The length of the wool fibre largely determines whether it will be manufactured on the woollen or the worsted system.

How To Make a Living Crafting Sheep's Wool

Wools up to about 35 mm in length are manufactured on the woollen system and are referred to as clothing wools, whereas wools longer than 35 mm are processed on the worsted system. The latter wools are known as combing wools. It must be remembered that there is staple length as well as straight fibre length to consider. The evidence is overwhelming that there is a close relationship between the length of staples and the mean straight length of the fibres within the staples. Due to this close relationship between mean fibre length and staple length a wool clip can be successfully classed for length if there are staple length differences between fleeces.

Some variability of fibre length is important because it enables the spinner to spin more evenly and to enable him to blend properly. However, a great variation in length results in weaker and less extensible yarns Walls, As a rule the longer the wool, the longer and also stronger and more uniform yarn can be spun from a given weight of wool. The carding operation is a very severe one and a large percentage of fibres is broken.

This results in a decrease of average fibre length and an increase in the percentage of short and very short fibres. The term 'tearage' refers to the removal of the very short fibres in the combing process.

It is an important subject both from the standpoint of costing and from its effect upon the spinning property of the wool. The short fibres which are removed during combing are known as Noil and the remaining longer fibres are known as the Top. As noil has less than half the value of top, the percentage of wool removed as noil has considerable commercial significance and therefore in estimating the value of any lot of wool, it is necessary for the buyer to examine the wool for this feature in addition to those previously mentioned.

Walls stated that when there is no break in the wool, the finer and hence weaker fibres tend to give more noil than the coarser fibres. A break in the staple results in increased fibre breakage and a higher percentage of noil. Seasonal changes cause a thinning of the fibres that is enhanced by poor nutrition, but the final stimulus causing the break is usually a stress condition brought on by disease or sudden exposure to wet cold conditions, etc.

Weathering also has a marked adverse effect on the soundness of wool. Degradation of wool, especially in the tip portion of the staple, takes place on the back of the sheep and to a lesser extent on the other parts of the body of the sheep due to exposure to sunlight, dust and heat.

It was found that the wool component in the card losses come mainly from the staple tips which had been weathered during growth. In an open fleece the fibres maybe more deeply damaged than in the case of a dense fleece.

In order to produce a sound root to tip wool the weathering of the wool on the sheep's back should be limited as far as possible. Consequently, the penetration of dirt into the wool staples promotes damage Le Roux, The adaptability of the animal to a certain environment also proved to have an effect on the degree of weathering Snyman, Severe weathering of the extreme tip usually occurs during the hot summer months.

During this period long wool is liable to be more deeply weathered than shorter wool. Deeper weathering of the wool in the staple can be limited by selecting and breeding for better substance and a better staple formation. From a management point of view the degree of weathering deeper into the staple can be reduced by changing the shearing time: The availability of shade in camps especially trees or open sheds is recommended as the most practical method Venter, ; Venter, Nel and Edwards, It is thus clear that a sound, well nourished wool with a good tensile strength from base to tip is the ideal from the manufacturer's point of view as it will give the least fibre waste and cause the least problems during manufacture and will result in a high quality end-product.

Superfine wool is used for the manufacturing of very light materials, while strong wool is used for coarser materials such as blankets and carpets. Wiggens stated that mean fibre diameter determines the spinning performance of wool for fine yarns and in fabrics it is associated with softness, warmth and flexibility.

relationship between wool fineness and crimp frequency

It is also known that finer fibres result in smoother and softer handling fabrics. Finer wools are also more valuable than thicker wools as stated by Whan The impact of fibre fineness on wool values is much more pronounced in the superior styles and between finer counts. However, there are realistic differences in wool values, even in the poorer styles, which stem directly from fibre fineness effects. The relationship between spinning count, fibre thickness and number of crimps per inch 25,4 mm crimp frequency as compiled by Duerden led to the use of crimps per inch 25,4 mm as an indication of the fineness of wool.

Whitely pointed out that in practice the classer is forced to rely on the relationship between staple crimp frequency and diameter. A large variation in the nature of crimping in relation to fibre thickness generally occurs. As far as South African Merino wool is concerned, Bosman showed that the Duerden relationship only holds in 28 percent of the cases while 36 percent proved to be over-crimped and 36 percent under-crimped. Corresponding deviations were noted by Lang in Australian Merino wool and appeared to vary within flocks and different strains.

Lately, various studies showed that the South African wool clip is to a large extent undercrimped. The commercial wool producer and stud breeder have for years emphasised the production of a good quality wool kind handle. The logical consequence was that the wool clip has become more and more under-crimped Kruger, ; ; Uys, In the majority of cases the wool is actually much finer than indicated by crimps. As fibre diameter is accepted as the most important factor in processing it is clear that the traditional appraisal system for fineness has become insufficient.

Objective measurement of fibre diameter is thus the only means of ensuring that a fair price is paid for greasy wool sale lots. To base the breeding policy on fibre thickness alone will not be sufficient.

Importance of certain greasy wool characteristics

Van Wyk concluded "assuming that the experienced sorter may be able to estimate fibre thickness without being misled by crimping, he has to choose between the two. In any case, variations in the relation between fibre thickness and crimping will result in a lack of uniformity in the sorted lot". Research has shown that wools of which the crimps and fibre thickness comply with Duerden standards have certain desirable properties.