Short Draw Technique

Short Draw Preparation

Traditional preparation for short draw spinning is combing, as combing requires the long stapled fibres preferred for the short draw technique, and it also leaves the fibres parallel, which is a characteristic of short draw spun yarns. The combed fibre can then be drafted to form a sliver or roving (if the fibres are twisted slightly after drafting, it is called a roving- if not, it is a sliver), or spun directly.

The short draw technique can be done from carded rolags, as well, but this does not produce a strictly worsted yarn. Yarns spun from a rolag will not have all the fibres parallel to the yarn though, with the short draw technique, many will be. Drum carded fibre, however, does have the fibres all parallel to each other, and thus can be used to create a strictly worsted yarn.

In use

Short draw is one of, if not the first method that a hand-spinner will learn when they learn to spin. It is simpler, and requires less confidence and practice to create an even yarn, than the long draw technique. However, many hand spinners will use a combination of short draw and long draw techniques. For example, it is common for a worsted short drawhandspinner to allow the twist to get between the two hands, as is done in long draw. Though the spinner may follow the short draw technique in all other points, this is not technically short draw, and doesn't have a commonly recognized name of its own. Short draw is much more widespread in its use than long draw, as many spinners do not know how to use the long draw technique.

The lack of elasticity in short draw spun yarns make them perfect for weaving, especially for the warp. It makes them less desirable for knitting in general, as the yarn doesn't fluff up and fill out the stitch, though it does make for good stitch definition.

The original spinning machinery was based on the short draw technique. Instead of an active and passive hand, the drafting was done by two sets of rollers moving at different speeds. However, the short draw characteristics remain: the fibres in the resulting yarn are all parallel, and there is no twist in the drafting area. Even in the modern day, many spinning machines are based on this principle.

Staple

Staple is a term referring to naturally formed clusters or locks of wool fibres throughout a fleece that are held together by cross fibres. The staple strength of wool is one of the major determining factors when spinning yarn as well as the sale price of greasy wool.

Virtually all fleece and better grade wool skirtings sold at auction in Australia are objectively measured prior to the sale with the average results printed in a catalogue.staples

Staple strength is calculated as the force required to break per unit staple thickness, expressed as newton’s per kilotex or N/tex. Position of Break (POB) is measured in conjunction with staple strength and is a measure of the position in the staple (base, mid or tip) where it will break given enough force. Forty or more staples must be measured to in order to conform to the Australian Standard. Wools under 30 newton’s per kilotex are considered tender. Currently wools over 40 newton’s per kilotex are preferred and attract a premium. Seasonal conditions or the health of the sheep may influence the soundness (strength) of the wool.

The Australian Standard requires that sale lot has a minimum of 55 staples measured with the average calculated and produced. The variability of this measure is reported as the coefficient of variation (CV%). Staple length generally determines the end use of wool, that is, whether it will be used in weaving or knitting. The longer wools are processed in the worsted system (weaving), which are called combing types, and are generally around 51 mm and longer. Short stapled wools are more profitably used in the woollen section where high grade material may be produced from superfine wool. Staple length (mm) is highly correlated with mean fibre length in the top (hauteur).

Although traditionally, staple length only referred to animal fibres, it is now used when referring to animal and manufactured fibres as well.

The opposite term is filament fibre, which is fibre that comes in continuous to near continuous lengths for use. Silk, taken from the cocoon of a silkworm, is called a silk filament.

Wool Classing

Wool classing is an occupation for which people are trained to produce uniform, predictable, low risk lines of wool. This is carried out by examining the characteristics of the wool in its raw state. The characteristics which a wool classer would examine are:

Breed of the sheep: Shedding breeds will increase the risk of medulated and/or pigmented fibres. Any sheep likely to have dark fibres should be shorn last to avoid contamination. The age of the sheep will have a bearing on the fibre diameter and value of wool, too.

Chemical usage: Ensure that all rules have been followed.

Brands, seedy jowls and shanks: Must be removed from fleeces and broken.

    Stain: Must be removed from bellies and fleeces and identified in a separate line.

Wool crimp: The number of bends per unit length along the wool fibre approximately indicates spinning capacity of the wool. fibres with a fine crimp have many bends and usually have a small diameter. Such fibre can be spun into fine yarns, with great lengths of yarn for a given weight of wool, and greater market value. Fine fibres may be utilised in the production of fine garments such as men's suits whereas the coarser fibres may be used for the production of carpet and other sturdy products. Crimp is measured in crimps per inch or crimps per centimetre. Average diameter or mean fibre diameter is measured in micrometres (microns). For generations, English wool-handlers categorized wool along the above lines estimating spinning capacity by eye and touch. This spread worldwide as the Bradford system.

Wool Strength (also known as tensile strength) determines wool's ability to withstand processing. Weaker wools produce more waste in carding and spinning. Weaker wools may be used for production of felt, or combined with other fibres, etc.

Wool colour: Indicates whether wool is able to be dyed in light shades. Colour may be graded depending upon the natural colour, impurities and various stains present. Severely stained wool decreases prices dramatically. However, it is difficult to assess colour accurately without proper measurement, since some stains will wash out in the processing, whereas others are quite persistent.

The fleece is skirted to remove excess frib, seed and burr etc to leave the fleece as reasonably even as possible in good respects. The parts of wool taken from a sheep are graded separately. The fleece forming the bulk of the yield is placed with other fleece wool as the main line, other pieces such as the neck, belly and skirting’s (inferior wool from edges) are sold for such purposes where the shorter wools are required (for example: fillings, carpets, insulation). Whilst in some places crimp may determine which grade the fleece will be placed into, this subjective assessment is not always reliable and processors prefer that wools are measured objectively by qualified laboratories. Some of the superfine wool growers do in shed wool testing, but this can only be used as a guide. This enables wool classers to place wool into lines of a consistent quality. A shed-hand, known as a wool presser, places the wool into approved wool packs in a wool press to produce a bale of wool that must meet regulations concerning its fastenings, length, weight and branding if it is to be sold at auction in Australasia. All Merino fleece wool sold at auction in Australia is objectively measured for fibre diameter, yield (including the amount of vegetable matter), staple length, staple strength and sometimes colour.

Classers are also responsible for ensuring that a pre-shearing check is made to ensure that the wool and sheep areas are free of possible contaminants. They are to supervise shed staff during shearing and train any inexperienced hands. At the end of shearing classers have to provide full documentation concerning the clip.

TPI

 I (twists per inch or turns per inch) is a term used in the textile industry. It measures how much twist a yarn has, and can be calculated by counting the number of twists in an inch of yarn.

    Variation per yarn

Twist is needed in yarn to hold the fibres together, and is added in both the spinning and plying processes. The amount of twist varies on the fibre, thickness of yarn, preparation of fibre, manner of spinning, and the desired result. Fine wool and silk generally use more twist than coarse wool, short staples more than long, thin more than thick, and short drawn more than long drawn.

The amount of twist in a yarn helps to define the style of yarn- a yarn with a lot of air such as a woollen yarn will have much less twist than a yarn with little air, like a worsted yarn. It also affects the stretchiness of the yarn, strength, the halo of the yarn, and many other attributes. Filling or weft yarns usually have fewer twists per inch because strength is not as important as with warp yarns, and highly twisted yarns are, in general, stronger. Warp yarns have to be stronger so that they can withstand the tension of the loom.

    Hand-spinning

Hand-spinners use the number of twists per inch often. Because the amount of twist defines a lot about a yarn, the number of twists per inch is an important measure to recreate a yarn. As a spinner spins, they will often stop every few minutes to check to see that the number of twists per inch are the same throughout the yarn, as well as that the number of wraps per inch (the thickness of the yarn) are the same. Measuring the number of twists per inch while spinning singles also helps the spinner create a balanced yarn plying.

tpi - part 2

The number of twists per inch can, in plied yarns, be determined by counting the number of bumps in one inch, and divide by the number of singles (the strands plied together to make the yarn). If the picture to the right, for example, was of an inch of 2 ply yarn, then the number of twists per inch would be 6 divided by 2, or three, as there are six bumps, and it is a two ply.

While this method works very well with plied yarns, singles don't have bumps to count. One way to determine the tpi for a single is to add a contrasting color fibre when spinning it, and then count the number of times the contrasting fibre has wrapped around the yarn. Another method is to measure an inch of yarn, and untwist it, counting how many full revolutions it takes until there is no twist left. This can be done by inserting two paper-clips into the yarn, at an inch apart, thus making it easier to count a full revolution. A less precise method is to allow the single to ply against itself: the resulting two ply yarn is about half the number of twists per inch of the single. Thus one can roughly find the number of twists per inch for the single, or one can use the doubled back yarn as a measure.

With yarn that is both thick and thin, than it is best to count over several inches and average them. This is because the number of twists per inch will tend to vary from the thin and thick sections.

    In the industry the number of twists per inch is calculated as:

   tpi

Where TM is the Twist Multiplier, also known as K or the Twist Factor. This Twist Multiplier is an empirical parameter that has been established by experiments and practice that the maximum strength of a yarn is obtained for a definite value of K. In the case of ring spun cotton yarns, for example, the following values of K have been found to give the best results.

    Warp yarns, 35's and less 4.75

    Warp yarns, 35's to 80's 4.50

    Warp yarns, 80's to 110's 4.25

    Filling yarns, medium numbers 3.50

 

Copyright © 2017 whorldropspindle