FAQ

“Narrow fabric is a term given to any fabrics having Width upto 12” or 300 centimeter but with distinct selvedge at both sides.”

Today ‘Narrow Fabrics’ are being used in apparel Industries, orthopedical industries, electronic industries, car industries etc. Some of the names of popular Narrow Fabrics are listed below:

Elastic tapes for gents under garment
Elastic Tapes for ladies under garment
Shoe elastic
Saddlery tapes
Sling tap-e/Webbing
Tapes for luggage industries
Satin ribbon for printable tapes
Hook and loop tape
Glass fibre tape for insulation
Bandage tape
Carpet yarn etc

Among Narrow fabric, Elastic today has got very significant role to play in hosiery industry. Irrespective of quantum of elastic used per garment, it is one of the basic accessories for hosiery garments specially underwear, trunk, tops or waistband, due to the fact that property of the elasticity of elastic completes the functional properties of the side garments. Gone are the days of using rigid cords and niwar in garments, with the availability of good quality elastic webbing/tapes which enhance the wearer comforts and function values of the garment.

There are 3 types of elastic tapes / webbing in the market.
Braided
Knitted
Woven


In all cases elastromeric core is laid longitudinally to give length way elasticity.

BRAIDED: Tapes are made on principle of plating of human hair, yarns and naked rubber so arranged, cross the fabric diagonally from side to side and at the same time pass under and over each other. Braided tape has got very high elongation but width become very narrow when stretched. It is mostly used for narrow end products in some cases ‘Leg Elastic in underwear.

KNITTED: Tapes are made on machine based on CROCHET KNITTING principle with synthetic yarns and naked rubber. It is mostly used as INSERT elastic for hosiery garment. Due to naked rubber & knitting type it has got very good extensibility and economical to produce as many processes of manufacturing are eliminated.


WOVEN ELASTIC: webbing / tapes are woven on Looms with interlacement of warp and elastic yarn. In 90% cases in woven elastic, core rubber is double covered with yarn. This extra protection, with better dimensional stability, good power, better retention value, more possibilities of various design, scope of inscribing brand name etc, has given woven elastic an edge over others.

For any elastic tape the main ingredients is rubber or elastomaric yarn used. The quality and elasticity of elastic webbing is in absolute proportion to the quality of rubber or elastromaric yarn.


There are two type of rubber.
EXTRUDED rubber with round cross section from latex.
Cut rubber by cutting vulcanized rubber sheet with square cross section.
The numbering system of rubber, unlike other textiles is different. Count of rubber is the number of threads that can be placed side by just touching each other in one inch, means in 40 gauge rubber one inch can accommodate 40 ends. Cut rubber has more cross section area and high heat resistant properties then extruded round rubber. In 90% cases elastic webbing are made with extruded latex with round cross section, as these are easily available with various degrees of heat resistance properties and with better launderable properties. Very high heat resistant rubber gives discoloration on garments after few washes.


Storage of rubber is important as it is badly affected by oil and grease, prolonged sunlight and artificial light exposure. High temperatures also lead oxidation, so the storage area should be cool (18 to 20 C) for both rubber thread as well as elastics. Longer storage of bare rubber also detoriates its elongation. Study days that 3-4 months of storage shall tend to make it brittle. So a first out policy should be adopted by store.

Numbers of ends per elastic tapes are going to vary with following factors such
width
end use
modulus and stretch required for end use
Gauge / number of rubber etc.
end use

However generalization is practically not possible. For practice 16 rubber ends of 38th gauge latex round cross section is fairly good combination for one inch elastic webbing for underwear elastic is also getting thinner by using much finer gauge rubber with more number of ends to match the requirement of end use.

Now a days lot of webbing are made out of “SPANDEX” unlike rubber has multifilament of segments of polyurethane. It is expressed in DENIER. Spandex has got following real advantage over latex rubber
5 to 6 time more durable than natural rubber
Retention value, power of coming back to its original position, is higher which is necessary to keep the shape of the garment
Much more powerful having more modulus for example a 75 gauge spandex can match the power of 52 gauge rubber
It is dyeable
Resistant to a lot of chemicals
Production is not dependent on agriculture etc.

Considering all these factors, webbing made out of spandex (Lycra is spandex) are found out to be superior.

To select a right tape, first select the end use, where you want to use them, because end use shall dictate the properties of elastic. For selecting underwear elastic, following aspects can be look into:-
Place one meter of tape on a flat table there should not be any weaving defects
it should lie absolutely relaxed, there should be no curvature and no wavy ness, and preferable with special weave for skin protection, if the elastic is not backed by cloth at the time stitch.
When stretched by hand, the stretch should not be less than 120% and not more than 140%.
Length of tape on garment should be decided in such a manner that 20% stretch in elastic to be unused when worn by wearer to protect the elastic.
50 times stretch and relax should not give any wrinkle. Marking of 10cm when relaxed on tape, must come back to its original position of marking within a few minutes after releasing the force.
Check width way rigidly to prevent folding on waist.
To stretch 50% of the elastic, the weight should be between 240gms to 280gms per centimeter width.
Washing in hot water and machine should be avoided. In natural wash and natural drying the shrinkage should not be above 7% - 8%.

Other than rubber and elastomer, elastic webbing are getting made with following raw materials, some times solely with one type or with mixture 4 to 5 raw materials together as components.
Cotton yarn
Rayon yarn
Polyester texturised (Natural as well as dyed)
Polyester crimp
Nylon crimp natural and dyed
Nylon stretch-Dyed
Viscose staple
P V 85% and 15% or 60&40% mixture Dyed
Full spun-Dyed and bleached
Flat polyester


It is surprising, in some webbing, warp may be polyester, figure warp may be nylon covering yarn may be viscose staple or texturised polyester and weft may be flat polyester, making very difficult to synchronized all the properties of them in to one. It is all the more difficult as elastic webbing specially woven elastic is subject to finishing treatment. When subject to heat, different types of yarn behave differently.


Selection of yarn absolutely based on the final end product and governed by the economics. 20 years back all underwear elastic were made from cotton / Rayon which was perfectly suitable for tropical countries like Indian. Now 80% elastic webbings, a main raw material is of polyester in various forms. Even nylon crimp for better SKIN effect is replaced by polyester crimp.


For testing elastic qualities and its durability one must follow:- Indian standard specification for elastic tape IS9686, 1980: Thought the standard prescribed by IS9686 is not always acceptable as this standard is based on
Cotton yarn
Long ago i.e. 1980
Standard is not based on end uses
Standard cannot be same for knitted woven braided.

But testing procedure is really good. Each and every elastic webbing factory must follow this procedure.

Following standard Testing should be carried out as prescribed by IS9686.
Thickness
Extension load per centimeter width required to produce on extension of 50% in tape
Limit of useful extension: by way plotting graph & drawing HYSTERESIS CURVE
Tension decay under constant stretch (75% of its stretch) for 18hrs only 5% losses allowed.
Fatigue test: stretch & relax 300 times & see no wrinkle / no visible defects and no deformation.
Color fastness: (a) Rubbing fastness (b) Wash fastness must match Grey scale “5”
Wash test for Contraction: after washing in 60c Temperature with material and water ratio 1: 40 with ½ liter soap solution in washing machine. Dry naturally. Only 7% to 8% contraction allowed.
The Accelerated ageing: Treating the sample for 96hrs with 70c temp.In air heated oven. Then b,c,d & e to be tested again, 75% of the original value must retain.

Apart from convertion elastic, so many other substitutes have come into market. Some of the examples are:

Rubber strip: The bare rubber strip available with width ranging from 4mm to 18mm for using it directly as insert elastic. The main advantage of this rubber strip is that it has got no contraction before and afterwards in washing.
Mobilon (Polyurethane elastic strip) are being used in garment industries but not yet penetrated in underwear elastic.
Elasticated hosiery cloth: Elasticated hosiery cloth (stretch fabric) getting stitched in folded form is also getting used in place of elastic band. Though expensive, gives very smart look because body cloth and waistband can be produced with same color and properties.
Elastic webbing / Tapes are nothing but industrial raw materials to so many industries. Including Hosiery industries. Using these precious and important raw materials as per the demand of end product & using it to its optimum proportion etc, is entirely in the hands of the designer of the garment.
Through this article, a very small effort is made to minimize the problems and explain the various facts, so that ultimate wearer / user can feel the comfort and enjoy the stretchibility and durability.