The Burn Test to Identify Textile Fibers


The burn test is a simple, somewhat subjective test based on the knowledge of how particular fibers burn. Be prepared to note the following when testing your fibers:
• Do the fibers melt and/or burn?
• Do the fibers shrink from the flame?
• What type of odor do the fumes have?
• What is the characteristic(s) of any smoke?
• What does the residue of the burned fibers look like?

The burn test is normally made on a small sample of yarns or thread which are twisted together. Since the fiber content of yarns used in one direction of a fabric are not always made up of the same fibers used in the other direction, warp and filling yarns should be burned separately to determine the entire fiber content of the fabric. This test is very helpful in determining whether a fabric is made from synthetic or natural fibers, but it is not foolproof and the characteristics observed during the burning test can be affected by several things. If the fabric /yarn contains blends of fibers, identification of individual fibers can be difficult. Two or three different kinds of fibers burned together in one yarn may also be difficult to distinguish. The odor and burning characteristics exhibited may be that of several fibers, thus making your results difficult to analyze. Finishes used on the fabric can also change the observed characteristics.

  • Pull a small sample of at least six to eight yarns from your fabric about 4 inches long, and twist them together into a bundle about 1/8 inch in diameter. You can also use a small snippet of the fabric if you only need to determine whether it is a synthetic or natural fiber fabric and you are not seeking to determine the specific fiber(s) that make up the fabric.
  • Hold one end of the bundle with tweezers over a sink or a sheet of aluminum foil (about 10 to 12 inches square) to protect your working area. If the sample ignites it can be dropped into the sink or on the foil without damage. Use either a candle or a match (automatic lighters work well) as your flame.

Potential Test Results

Natural, Organic & Manmade Fibers

In general, if the ash is soft and the odor is of burning hair or paper, the fabric is a natural fiber. Cellulosic fibers (cotton, linen and rayon) burn rapidly with a yellow flame. When the flame is removed, there is an afterglow, then soft gray ash.

Cotton: Ignites on contact with flames; burns quickly and leaves a yellowish to orange afterglow when put out. Does not melt. It has the odor of burning paper, leaves, or wood. The residue is a fine, feathery, gray ash.
• Hemp: Same as cotton
• Linen: Same as cotton
• Ramie : Same as cotton
• Rayon : Same as cotton, but burns slowly without flame with slight melting; leaves soft black ash.
• Silk: Burns slowly, but does not melt. It shrinks from the flame. It has the odor of charred meat (some say like burned hair). The residue is a black, hollow irregular bead that can be easily to a gritty, grayish-black ash powder. It is self-extinguishing, i.e., it burns itself out.
Tencel : Same as Rayon
• Wool, and other Protein Fibers: Burns with an orange sputtery color, but does not melt. It shrinks from the flame. It has a strong odor of burning hair or feathers. The residue is a black, hollow irregular bead that can be easily crushed into a gritty black powder. It is self-extinguishing, i.e., it burns itself out.

Synthetic Fibers

Most synthetic fibers both burn and melt, and also tend to shrink away from the flame. Synthetics burn with an acrid, chemical or vinegar-like odor and leave a plastic bead.
Other identifying characteristics include:
• Acetate: Flames and burns quickly; has an odor similar to burning paper and hot vinegar. Its residue is a hard, dark, solid bead. If you suspect a fabric is acetate, double-check by placing a scrap of it in a small amount of fingernail polish remover-if you’re correct, the fabric will dissolve
• Acrylic: Flames and burns rapidly with hot, sputtering flame and a black smoke. Has an acrid, fishy odor. The residue is a hard irregularly-shaped black bead.
• Nylon: It will shrink from the flame and burn slowly. Has an odor likened to celery. Its residue is initially a hard, cream-colored bead that becomes darker gray.
• Olefin/Polyolefin: Has a chemical type odor. The residue id a hard, tancolored bead. The flames creates black smoke.
• Polyester: It will shrink from the flame and burn slowly giving off black smoke. Has a somewhat sweet chemical odor. The residue is initially a hard cream-colored bead that becomes darker tan.
Spandex: It burns and melts, but does not shrink from the flame. It has a chemical type odor. Its residue is a soft, sticky black ash.

 

Yarn Conditioning


Why conditioning is required?

Moisture in atmosphere has a great impact on the physical properties of textile fibres and yarns.Relative humidity and temperature will decide the amount of moisture in the atmosphere. High relative humidity in different departments  of spinning is not desirable. It will result in major problems.  But on the other hand, a high degree of moisture improves the physical properties of yarn. Moreover it helps the yarn to attain the standard moisture regain value of the fibre. Yarns sold with lower moisture content than the standard value will result in monetary loss. Therefore the aim of  CONDITIONING  is to provide an economical device for supplying the necessary moisture in a short time, in order to achieve a lasting improvement in quality.

In these days there is a dramatic change in the production level of weaving and knitting machines, because of the sophisticated  manufacturing techniques. Yarn quality required to run on these machines is extremely high. In order to satisfy these demands without altering the raw material, it was decided to make use of the physical properties inherent in the cotton fibres. Cotton fibre is hygroscopic material and has the ability to absorb water in the form of steam. It is quite evident that the hygroscopic property of cotton fibres depends on the relative humidity. The higher the humidity, more the moisture absorption. The increase in the relative atmospheric humidity causes a rise in the moisture content of the cotton fibre, following an S-shaped curve.

The relative humidity in turn affects the properties of the fibre via the moisture content of the cotton fibre. The fibre strength and elasticity increase proportionately with the increase in humidity. If the water content of the cotton fibre is increased the fibre is able to swell, resulting in  increased fibre to fibre friction in the twisted yarn structure. This positive alteration in the properties of the fibre will again have a positive effect on the strength and elasticity of the yarn.

CONTEXXOR CONDITIONING PROCESS BY XORELLA:

The standard conventional steaming treatment for  yarn is chiefly used for twist setting  to avoid snarling in further processing. It does not result in lasting improvement in yarn quality.  The steaming process may fail to ensure even distribution of the moisture, especially on cross-wound bobbins(cheeses) with medium to high compactness.  The thermal conditioning process of the yarn according to the CONTEXXOR process developed by XORELLA  is a new type of system for supplying  the yarn package.

The absence of Vacuum in conventional conditioning chambers, prevents homogeneous penetration. The outer layers of the package are also too moist and the transition from moist to dry yarn gives rise to substantial variations in downstream processing of the package, both with regard to friction data  and strength.

Since the moisture is applied  superficially in the wet steam zone or by misting with water jets, it has a tendency to become re-adjusted immediately  to the ambient humidity level owing to the large surface area. Equipment of this king also prevents the optimum flow of goods and takes up too much space.

PRINCIPLE OF WORKING:

Thermal conditioning uses low-temperature saturated steam in vacuum. With the vacuum principle and indirect steam, the yarn is treated very gently in an absolutely saturated steam atmosphere. The vacuum first removes the air pockets from the yarn package to ensure accelerated steam penetration and also removes the atmospheric oxygen in order to prevent oxidation. The conditioning process makes use of the physical properties of saturated steam or wet steam (100% moisture in gas-state). The yarn is uniformly moistened by the gas. The great advantage of this process is that the moisture in the form of gas is very finely distributed throughout the yarn package and does not cling to the yarn in the form of drops. This is achieved in any cross-wound bobbins, whether the yarn packages are packed on open pallets or in cardboard boxes.

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pic: XORELLA CONDITIONING SYSTEM

  • ADVANTAGES OF CONTEXXOR PROCESS:
  • saturated steam throughout the process
  • even penetration of steam and distribution of moister
  • lowest energy consumption with XORELLA ECO-SYSTEM
  • short process time
  • absolute saturated steam atmosphere of 50 degree C to 150 degreees C.
  • no additional boiler required, the steam is generated in the system
  • minimum energy consumption(approx. 25 KWh for 1000 kgs of yarn)No tube buckling in case of mad-made yarns
  • treatment of all natural yarns, blends, synthetics and microfibre yarns.
  • low installation and maintenance cost
  • preheating for trollys and plastic tubes to avoid drops (Wool)
  • standardize sizes
  • length up to 20 meters (66 feet) and max. temperature deviation of 1°C
  • various loading and unloading facilities
  • no contamination of the treated packages
  • energy recovery option offered by indirect heating system using steam or hot water
  • no special location required, the systems can be operated next to the production machines.

BENEFITS ACHIEVED OUT OF CONDITIONING:

FOR KNITTING:

The treatment temperature for knitting yarn is held below the melting point of the wax. Temperatures for unwaxed

yarn are coordinated to the compatibility fo each individual type of yarn

  • Upto 20% greater efficiency due to a reduction in the unwinding tension
  • fewer needle breaks
  • uniform moisture content and friction values
  • regular stitch formation
  • no change in size of finished articles
  • no extra dampening required
  • free from electrostatic
  • less fly hence less problems. It helps if the yarn is  running on a closer gauge machines

NOTE: Please note that the wax applied should  be able to withstand min 60 degree centigrade.  If low quality wax is used, it will result in major problem. Conditioning should be done at 55 to 60 degree centigrade.

FOR WEAVING:

  • upto 15% fewer yarn breaks due to greater elongation
  • less fly, resulting in a better weaving quality
  • increased strength
  • increased take-up of size, enhanced  level of efficiency in the  weaving plant
  • softer fabrics

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Pic: improved strength                                              Pic: improved elongation

FOR TWISTING:

Conditioning and fixing of the twist at the same time in a single process.

FOR DYEING:

  • no streaks
  • better dye affinity

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Pic: dye pick up of conditioned and unconditioned yarn

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COM-4 AND ELITE YARNS


COM-4 CONCEPT:

With the ComforSpin   technology a new yarn with perfect yarn structure – the COM4  yarn – has been established in the market. With the help of a microscope the structure of the yarns can easily be compared: The conventional ring yarn shows to be far less perfect than commonly assumed. The long, protruding fibres cause a number of problems in downstream processing. COM4  yarn shows a very compact structure with highly parallel fibres and much less disturbing hairiness.

The air current created by the vacuum generated in the perforated drum condenses the fibres after the main draft. The fibres are fully controlled all the way from the nipping line after the drafting zone to the pinning triangle.clip_image002

An additional nip roller prevents the twist from being propagated into the condensing zone. The compacting efficiency in the condensing zone is enhanced by a specially designed and patented air guide element.

Optimal interaction of the compacting elements ensures complete condensation of all fibres. This results in the typical COM4 ® yarn characteristics.

The ComforSpin ® technology allows aero-dynamic parallelization and condensation of the fibres after the main draft. The spinning triangle is thus reduced to a minimum. The heart of  ComforSpin   machine is the compacting zone, consisting of the following elements:

• perforated drum

suction insert

• air guide element

The directly driven perforated drum is hard to wear  and resistant to fibre clinging. Inside each drum there is an exchangeable stationary suction insert with a specially shaped slot. It is connected to the machine’s suction system.

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THE ELITE YARN:

The operating method of the SUESSEN EliTe  Spinning System is well-known.After the fibres leave the drafting system they are condensed  by an air-permeable lattice apron,which slides over an inclined suction slot.The fibres follow the outer edge of this suction slot and at the same time  they perform a lateral rolling motion.

Above the front bottom roller of the drafting system,the fibre band  influenced by high draft  is spreading.In the area of the suction slot,which is covered by the lattice apron,the fibre band is condensed.Commencing from the semi-dotted clamping line of the EliTe Q Top Roller,twist is being inserted.There is no spinning triangle.

The improvement achieved is shown in Fig .The left side displays the fibre triangle at the exit of a conventional ring frame drafting system.The twist imparted by the spindle cannot flow up to the clamping line.The outer fibres spread out and are thus more highly tensioned than those on the inside. The right side of the picture does not show a spinning triangle.The yarn twist flows right up to the clamping line.The yarn is round and smooth.

Since the spinning triangle is very very small, the end breaks will be very less and therefore the fly liberation will also be less.

Condensing of the fibre bundle,which follows the drafting process,can already be seen as a significant  development of the ring spinning technology.Condensed ring yarn is more  than a speciality.In view of its manifold advantages.

It is of technological importance that the suction level relevant for the condensing operation is exactly the same for all spinning positions. To fulfil this criteria,individual motors combined with suction units for  6 spinning positions,have  been arranged accordingly.This provides short air-flow distances with identical negative pressures at all spinning points .

During yarn formation all fibres are perfectly condensed and gathered parallel to each other in the compacting zone. Consequently all fibres are twisted in and contributing to the superior fibre utilisation rate compared to conventional ring yarn. The result is exceptionally low hairiness combined with higher yarn tenacity and elongation. These are the unique characteristics of these yarns.

ADVANTAGES OF COMPACT YARN:

• higher fibre utilisation clip_image005

• higher tenacity with same twist factor, or

• same tenacity with reduced twist factor for higher production

• lowest hairiness (highest reduction in hairs longer than 3 mm)

• fewer weak points

• better imperfections (IPI) values

• higher abrasion resistance

• greater brilliance of colour

• intensive dye penetration

• no singeing before printing

  • Due to better utilization of fibre substance it is possible to reduce yarn twist of  these Yarns,particularly of knitting yarns,by up to 20%,maintaining the yarn strength of conventional ring yarns.This increases yarn production. The ends-down rate in spinning these Yarns is reduced by 30 to 60%,which improves machine efficiency.
  • Applying the same winding speed as with conventional ring yarns,there are less raised points in these Yarns and the increase in yarn imperfections is reduced because they have a better resistance to shifting. Higher winding speeds are therefore possible with  compact yarns Yar ns .
  • In accordance with up to 20%twist reduction in spinning compact yarns ,the twisting turns can be reduced for certain types of yarn.As a result,production of twisting frame is increased and twisting costs are reduced.
  • Owing to the lower hairiness and higher tenacity of compact Yarns,the ends-down rate in beaming is reduced by up to 30%.Higher beamer efficiency,higher produc tion and fewer personnel for repair of ends-down in beaming are the consequence.
  • Compact  Warp yarns help to save up to 50%of sizing agent,while the running behaviour of weaving machi-nes is the same or even better. Cost can be saved  in sizing and desizing  processes.
  • Owing to the better work capacity of  compact Yarns ,ends down can decreased  by up to 50% in the warp and by up to 30%in the weft. Efficiency is consequently increased by 2 to 3%, production is increased and weaving costs are reduced.  In practice,the average ends-down rate is reduced by 33% per 100,000 weft insertions of  compact Yarns on rapier weaving  machines and by 45% on air-jet weaving machines.  Instead of a weft insertion of 500 –600 m/min with conventional ring yarn,700-800 m/min is possible with compact  Yarns on air-jet weaving machines.
  • Due to reduced Yarn hairiness,singeing can sometimes be dispensed with,or it can be carried out at a higher cloth advance speed.As a result,production costs are considerably reduced.
  • fibres upto 7% can be saved because singing can be avoided
  • Dyeing and Printing Improved structure of compact  Yarns and their reduced twist favours the absorption of colour pigments and chemical finishing agents.Saving of dyestuff is possible.
  • Owing to the  improved yarn strength, compact  Yarns are well suited for non-iron treatment of woven fabrics. In the course of such treatment,the strength of fabrics made from conventional ring yarns can decrease by up to 25%,with frequent problems in the manufacture of clothes. compcat Yarns make up for this loss in strength.
  • Knitting :Compact Yarns with their increased yarn strength and reduced formation of fluff permit to achieve higher machine efficiency and therefore production on knitting machines at a reduced ends-down rate,less interruptions and less fabric faults. Production costs therefore decrease. The enormously low hairiness of compact  Yarns often permits to dispense with usual waxing. Considerable cost saving is achieved because of this.
  • In knitting fibre abrasion reduced by 40% due to low hairiness. Fewer defects/ yarn breaks and  better quality. Less contamination on all machines by foreign fibres . Less wear of needles, guide elements and sinkers due to less dust in the compact Yarn . Low hairiness has positive impact on loop structure .  L Low pilling values get more and more important . In many cases single compact  Yarns substitute conventional ply yarns. Waxing can be reduced or completely dispensed with .
  • Compact  Yarns are much more suitable for warp knitting than conventional ring yarns,because of  their higher work capacity and lower hairiness. They are predestined to bear the high load due to numerous deflecting points with high friction in the warp knitting machine.
  • Due to better embedding of fibres (including short ones)in  compact  Yarn,approx.6%fewer combing noils are possible.
  • Cheaper carded qualities instead of combed qualities can be spun with the Compact  Spinning ystem.
  • in many cases single EliTe ® Yarns can substitute conventional ply yarns
  • new qualities can be developed, opening up a new creative scope for products

Hairiness Testing of Yarns

Hairiness of yarns has been discussed for many years,but it always remained a fuzzy subject. With the advent of compact yarns and their low hairiness compared to conventional yarns,the issue of measuring hairiness and the proper interpretation of the values has become important again.Generally speaking,long hairs are undesirable, while short hairs are desirable (see picture ). The  picture  shown below just give a visual impression of undesirable and desirable hairiness at the edge of a cops.

Figure:

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RING YARN                                                                  COMPACT YARN

There are two major manufacturers of hairiness testing equipment on the market,and both have their advantages and disadvantages. Some detail is given below.

USTER

USTER is the leading manufacturer of textile testing equipment. The USTER hairiness H is defined as follows .

H =total length (measured in centimetres) of all the hairs within one centimetre of yarn .

(The hairiness value given by the tester at the end of the test is the average of all these values measured, that is,if 400 m have been measured,it is the average of 40,000 individual values) . The hairiness H is an average value,giving no indication of the distribution of the length of the hairs.  Let us see an example

0.1cm 0.2cm 0.3cm 0.4cm 0.5cm 0.6cm 0.7cm 0.8cm 0.9cm 1.0cm total
yarn 1 100 50 30 10 5 6 0 2 1 0 398
yarn 2 50 10 11 5 10 0 5 10 0 11 398

Both yarns would have the same hairiness index H, even though yarn  is more desirable,as it has  more short  hairs and less long hairs,compared to yarn 2.

This example shows that the hairiness H suppresses information,as all averages do. Two yarns with a similar value H might have vastly different distributions of the length of the individual hairs.

The equipment allows to evaluate the variation of the value H along the length of the yarn.  The “sh value “is given, but the correlation to the CV of hairiness is somehow not obvious.A spectrogram may be obtained.

2.ZWEIGLE

Zweigle is a somewhat less well known manufacturer of yarn testing equipment. Unlike USTER,the Zweigle does not give averages. The number of hairs of different lengths are counted separately, and these values are displayed on the equipment. In addition, the S3 value is given,which is defined as follows:

S3 =Sum (number of hairs 3 mm and longer)

In the above example,the yarns would have different S3 values:

S3yarn 1 =2 .

S3yarn 2 =4 .

A clear indication that yarn 2 is “more hairy “than yarn 1.  The CV value of hairiness is given a histogram (graphical representation of the distribution of the hairiness) is given.

The USTER H value only gives an average,which is of limited use when analyzing the hairiness of the yarn.The Zweigle testing equipment gives the complete distributionof the different lengths of the hairs. The S3 value distinguishes between long and short hairiness, which is more informative than the H value.

Ten Fundamental Rules for Successful Operation of EliTe  Ring Spinning Machines:

  • EliTe Q Spinning Machines produce yarn of supreme quality and come up to the expectations.  Installation of the machine in the spinning  mill EliTe Q Spinning Machines have a considerable air flow rate –a machine with .1008 spindles sucks in about 60 cubic meter  of air per minute,i.e. it has the effect of a vacuum cleaner. The ambient air is sucked into machine and most of the fly and dirt contained in it is deposited on the EliTe Q Machine. Although EliTe Spinning Machines generate considerably less fly than standard ring spinning machines, they are soon covered with dust and fly if they are installed in the same room as conventional spinning machines. The fly has a negative effect on the yarn in the condensing zone and the smooth running of the lattice apron. As a result,the yarn is of substandard quality.

Rule .:EliTe Q Spinning Machines must be separated from conventional spinning machines.

  • Spinning room conditions: The fibres in the condensing zone are exposed to the room conditions without any protection. Our recommendations on the room conditions suitable for processing cotton and man-made fibres should be followed, therefore. If the air humidity is too high, there will be a higher tendency towards roller laps. If the air is too dry,t here will be more fly. If the room temperature is too high, there will be higher friction values and premature wear.

Rule 2:maximum room temperature:33 .C

humidity should be

  • max…,5 g water/kg air for cotton
  • min.9,0 g water/kg air for cotton
  • max..0,0 g water/kg air for synthetics
  • min.9,0 g water/kg air for synthetics
  • Position of the Eli Top in relation to the front bottom roller of the drafting system:  If the setting is correct, the top edge of the suction slot in the Eli Tube is precisely set at the nip line of the delivery top roller. If the nip line cuts the slot, condensation is impaired. The hairiness of the yarn increases and the tearing strength is reduced. If the nip line is behind the slot, part of the spinning torsion may get into the condensation zone, resulting in an increased ends-down rate and damaged lattice aprons.

Rule 3:The front top roller is precisely 3.5 mm offset towards the operator in relation to the front bottom roller of the drafting system.

  • Traverse mechanism:  The roving must run over the slot in such a way, that, from the operator ’s view, the  fibres move from the top right to the bottom left. If the fibres run over the slot top from the L.H. side,they make an S-shaped movement causing a certain unsteadiness in the condensing zone. This has a negative effect on the yarn values.

Rule 4:The traverse mechanism for the sliver should be adjusted in such a way that the traverse motion at the front of the drafting system does not exceed 4 mm,and that the l.h.limit position of the sliver is level with the L.H..edge of the top of the slot.

  • Cleaning the Eli Tubes and lattice aprons :Eli Tubes and lattice aprons are the most important components of the EliTe Q Condensing System. Careful maintenance is an important prerequisite for optimum yarn values. In the centre area, where the suction is active, a permanent air flow keeps the lattice aprons clean. To the left and right of this area, the lattice apron can be clogged by fine dust. With the time, this results in a considerable increase of the friction between the lattice aprons and the EliTube.  If this friction is too high, erratic running of the lattice apron and substandard yarn quality is the result. Therefore,lattice aprons and Eli Tubes should be removed from the machine from time to time and cleaned. This can be done when the machine is running. The time needed per box length is 5 min. The expenditure of time necessary for changing the EliTubes with lattice aprons is about  90 minutes for a machine with .1008 spindles, which corresponds to a loss of production of  90 minutes. For yarn count Ne 40, the production loss involved is less than 370 g. The cleaning frequency varies depending on the portion of fine dust of the cotton. As an average value, 500 operating hours may be taken into account. The aprons are cleaned in a washing machine or in an ultrasonic cleaning device.The EliTubes are cleaned using a damp piece of cloth. Damaged lattice aprons must be replaced. On EliTubes with considerable traces of wear, the inserts must be replaced.

Rule 5:Lattice aprons and Eli Tubes must be cleaned from time to time.

  • Measures to be taken in the case of laps at the front top roller Laps may occur in the case of unsuitable room conditions or damaged or inappropriately buffed cuts, or if the fibre material used is prone to the formation of laps. Large laps may block the delivery and front rollers and damage the cot of the blocked roller. If spinning is continued with damaged cots,periodic yarn faults will be the result. Consequently, a blocked Eli Top must be replaced by a new Eli Top and repaired in the service room. For this purpose,all operators should carry a spare Eli Top with them.

Rule 6:EliTops with blocked top rollers must be replaced by new top rollers.

  • Buffing the EliTe Q Top Rollers : The cots of the EliTe Q Top Rollers are subject to wear and should be buffed from time to time.The tension draft in the condensing zone –6 %as a general rule depends on the difference in diameter between the front top roller and the delivery top roller. Changed tension drafts may result in changed yarn parameters.

Rule 7:Make sure that the difference in diameter of the front top roller and the delivery roller corresponds precisely to the desired tension draft.

  • Checking the partial vacuum As a general rule,continuous control of the vacuum pressure is not necessary. When the whole machine is cleaned, we recommend, however,to remove also the connecting hoses between the suction tubes and the fans and to clean them.

Rule 8:Clean the connecting hoses with regular frequency.

  • Maintenance of the fans:  Fans may be clogged after a time,which has a negative effect on the suction.

Rule 9:The fans should be removed from the machine and cleaned once a year.

  • Spinning speed:  In the case of EliTe Q Spinning Machines, return on investment is not based on higher production, but on the production of yarn of supreme quality.  The Suessen recommendations concerning traveller speeds and running-in speeds for rings and travellers should be followed, therefore. Not the ultimate increase in speed, but the yarn quality leads to success.

Rule 10:Yarn quality is more important than quantity.

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