1. INTRODUCTION

Terry or Turkish towels were originated in Constantinople, Turkey, wherein these fabrics were woven in handlooms. In the middle of 19th century this technique of weaving towels was further refined in the European countries and took a shape of power driven looms (Hobson 1990).

Terry fabrics basically belong to the group of pile fabrics, wherein an additional yarn is introduced/inserted in such a manner that forms loop, called as pile, to give a distinct appearance. These fabrics can be produced either by weaving or by knitting, out of these two methods of terry fabric production, woven terry fabric, which is the first method invented, still has major share (Kienbaum 1978). This is because the quality of knitted terry fabric is not comparable to that of woven terry fabric. Besides the methods employed to manufacture the terry towels, other factors such as use of fibres, parameters of yarn, parameters of weaving, and methods of chemical processing are also play a significant role in determining the quality of terry towels (Swani et al 1984, Teli et al 2000).

2. HISTORICAL DEVELOPMENTS OF TERRY TOWEL WEAVING

Victor Hobson (1990) described various mechanisms of terry loom being developed at initial stage. He described that at primitive stage, like other fabrics, handlooms were used to manufacture terry towels, but to produce loops, it was necessary to insert long rods in the same direction that weft were inserted. Length/size of loops was dependent on the thickness of rods. Following the invention of power operated looms, mechanical means were used to insert and withdraw the wires but these were no longer used in production of terry towels due to the complexity of operation. According to Hobson (1990), all the basic mechanisms for pile formation such as loose reed, shifting of cloth fell, variable fall back controlled by a pattern chain for sculptured effects, etc., had been developed by the end of 19th century.

3. STATUS OF INDIAN TERRY TOWEL INDUSTRY

In India, terry fabrics are manufactured mainly in decentralized handloom and power looms sectors (Gangopadhyay et al 1999). Most of terry fabric centres are situated around Chennai, Erode, and Sholapur. However terry fabrics are also manufactured in organized sector. But the volume of production of terry fabrics in organized sector is much lesser than that of the production in decentralized sector. Till last decade only 10-15% of total terry fabric production was produced in organized sector (Kwatra 1994). Some of the prominent terry towel manufacturers in organized sector are Bombay Dyeing, Modern Terry Towels, Abhishek Industries, Garware Wall Paper, Welspun Polyesters, Trimbak Industries, Sharda Terry Towel, Santogen Exports, Vanasthali Textiles, etc. Most of the organised sector units are engaged in catering to market of export and high quality segment of domestic market, which covers mainly of hospitals, and leisure industry.

4. MECHANISM OF TERRY WEAVE

In terry fabric manufacturing, two sheets of warp threads run simultaneously, of which, one is kept under normal tension and other is kept under loose tension (Kienbaum 1978, Ramaswamy 1992). The threads of normal tension warp sheet are for ground and threads of loose tension warp sheet are for pile. The sequence of operations during weaving for pile formation in 3-pick terry is given below:

Insertion of first pick as per the design with loose beating
Allow a predetermined gap near the feel of cloth
Insertion of second pick following the first pick with loose beating
Insertion of third pick with heavy beating and bring all the three picks to the fell of cloth

Ramaswamy (1992) compared the 3 pick terry and 4 pick terry, and observed that 4-pick terry fabrics are heavy in structure and provide better quality in comparison to 3 pick fabrics.

5. LATEST DEVELOPMENTS OF TERRY WEAVING

Kienbaum (1978) described various production techniques, construction, and patterning range of terry towels. According to him, a variety of methods can be employed to manufacture terry towels, of which weaving, knitting, sew knitting and needle pile methods are important. Each of these methods gives fabric a different range of functional properties for use and care on the one hand and aesthetic appearance on the other.

Out of the above-mentioned techniques of terry towel manufacturing, weaving and knitting are used in major way. During the 20th century, a lot of developments in technology of terry towel looms have taken place with the main focus on to enhance productivity, operating speeds, quality, etc. for which work of some prominent loom manufacturers such as Vamatex, Saurer, Dornier, Nuore Pignone, etc., is worth mentioning. Various mechanisms of pile formation are microprocessor controlled, therefore, a high level of accuracy in accomplishment of operations is altogether achieved in the looms of present generation. Despite, the microprocessors are used in a big way in today's terry looms for controlling almost all the weaving operations, the basic principle of loop formation is still remain same as being invented at early stage.

6. FIBRES SUITABLE FOR TERRY TOWELS

Generally terry towels are used as bathing towels where its main function is to absorb water during the course of wiping of the wet body. It is therefore fibres that have greater ability to absorb water as well as have softer feel are preferably used in manufacturing of terry towels. The two fibres that have quality matching with the requirements of towels are cotton and linen. Linen has a rather harsher feel but it may not be a disadvantage in certain cases. The price of linen is also a barrier. Viscose staple yarn are also used as it possess adequate moisture absorption capacity but its ability to resist frequent laundering is poor as compared to cotton. It is therefore the bulk of towels are manufactured from cotton.

7. EFFECT OF YARN PARAMETERS

Among various parameters of yarn, linear density, twist per inch and packing density play a significant role in achieving desired quality of terry towels. Higher packing density of yarn resists absorbing more quantity of water due to availability of lesser space to retain water. Swani et al (1984) conducted a study on functional properties of terry towels produced by using the ring and the OE yarn in pile warp. Swani et al (1984) observed that there was no difference in water absorption rate in towels made out of OE yarn and ring yarn but the maximum absorption of water for OE towels was better than that of ring towels. Mukhopadhyay et al (1996, 1998) prepared a bi-component yarn by blending water-soluble PVA staple fibre with cotton fibre and used this yarn in pile warp for producing terry towels. After completion of mechanical processing of weaving, towels being prepared by using bi-component yarn were treated in boiling water to dissolve the water-soluble PVA component of yarn. As a result of dissolving of PVA fibres, the remnant yarn was more bulky, which lead to lower packing density of fibre in yarn.

Mukhopadhyay et al (1996, 1998) observed that the towels made out of bi-component yarn were better in terms of various functional properties as compared to the towels of ordinary ring spun yarn. Ishtiaque (1986a, 1986b) conducted study on effect of spinning process variables on distribution of fibres in cross section of ring spun yarn as well as rotor spun yarn. Ishtiaque (1986a, 1986b) in his study observed that the packing density of fibres in ring yarn increases with the increase of twist. Various researchers observed that the towels manufactured with the low twist yarn in pile warp have better functional properties in terms of softness and water absorbency (Mukhopadhyay et al 1996, 1998).

8. WEAVING PREPARATION

Conversion process of yarn into fabric requires many intermediate operations, wherein yarn has to subject with varied amount of tensions. Therefore, the yarn, that has to be used for weaving, must have adequate strength to bear with these tensile forces, otherwise it will show poor performance during fabric manufacturing (Rao 1998, Gangopadhyay et al 1999). Direct warping is generally used for preparation of ground warp beam while use of sectional warping machine for pile warp preparation is preferred. Venkatpathi (1999) discussed that yarn quality in terms of strength alone is not adequate for production of good quality of fabrics. In addition to yarn strength, other factors which play a crucial role in deciding weaving efficiency are uniformity, frequency of imperfections, long faults, slubs, count variation, twist variation and hairiness. Venkatpathi (1999) further added that many defects like slack end, pulled warp, sticky ends, broken pattern, etc., predominantly originate in preparatory section.

9. EFFECT OF WEAVING PROCESS VARIABLES

Swani et al (1984) assessed performance properties of terry towels made out of the open-end yarn and the ring spun yarn and found that there was no significant difference in the water absorption rate of ring and OE fabrics although yarn wicking rate was greater in fabrics of OE yarn. Absorption rate increased with increase in pile density but was not affected by pile ratio. Swani et al (1984) further added that maximum absorption for OE fabrics was better than for ring fabrics at lower fabric density and for comparable fabric weight. Ring fabrics showed better dry and wet abrasion resistance than OE fabrics. The abrasion resistance of the fabrics was maximum for moderate pile density and high pile ratio. The wet abrasion resistance was significantly lower than dry abrasion resistance of the fabrics.

Mukhopadhyay et al (1996, 1998) conducted studies on to improve the functional properties of terry towel fabrics made out of bi-component yarn. They developed a bi-component yarn comprising of cotton and a water-soluble synthetic fibre. The water-soluble fibre exhibited good compatibility with cotton during spinning. After weaving, water-soluble component of yarn was dissolved. This process reduced the twist level and resulted in a higher space in each loop. The resulting towel exhibited improved water absorbency, higher abrasion resistance, softer and lighter weight than towels woven using conventional yarns. The process had no adverse effect on light fastness or wash fastness.

Gangopadhyay et al (1999) conducted study on to assess manufacturing techniques of terry towels employed in decentralized sector with a view to identify measures to enhance productivity and functional properties. They assessed machines, processes and work methods followed at each stage of manufacturing such as winding, weft preparation, warping, sizing, weaving and wet processing. The team suggested modification in machines and process to achieve desired performance in quality and productivity of terry fabrics.

Mansour et al (1997) worked on to develop an expert system for terry weave. Most important weaving parameters being identified by them were cut and uncut loops, pile density and pile height. Manipulation of these weaving parameters affected various physical and mechanical properties such as water absorbency, tensile strength, abrasion resistance, fabric weight, thickness, handle etc.

Tarafdar et al (2002) has conducted studies for measurement of moisture transport in terry fabrics. In their study, they concluded that:

Surface water absorption increases with the increase in pile height.

With the increase in pile density, wicking behaviour increases both in warp and weft,
but quantitatively warp way shown more wicking absorbency than weft way.

With the increase in arial density of the fabrics, the wicking height increases.

The wicking height also shows an increasing order with the increase in thickness of the
fabrics.

Srivastava et al (1997, 1998) worked on optimisation of process parameters to improve functional properties of bi-component terry towel. The process parameters being considered as most influencing were twist in yarn, proportion of water soluble fibre (WSF) component, pile ratio and picks per inch. These parameters decide the terry towels functional properties such as moisture absorbency, water retention, drying ability, resistance to abrasion, softness and feel. Results indicated that optimal bi component towels in respect of above-mentioned functional properties had an 18% WSF component, 32 picks per inch and pile ratio of 1:4.5.

10. CHEMICAL PROCESSING OF TERRY FABRICS

Grey terry towels contain various unwanted constituents such as contents of size recipe, natural wax and colouring matters, fragmented seed coats, leaves, stems etc which need to be removed from the fabrics with a view to obtain desired functional as well as aesthetic properties in terms of softness, water absorbency, whiteness etc. As all above-mentioned impurities are embedded in yarn, which is strongly interlaced in fabric, therefore, removal of these impurities from the fabric is a complex job. Treatment of fabrics with a suitable combination of chemicals at required temperature and pressure for the specified duration helps in dissolving the deeply embedded impurities, while mechanical treatment in the form of stirring, rinsing, etc. helps in separating out the dissolved impurities from the fabric/yarn (Shenai 1981).

As the terry fabric contain piles/loops, therefore, the processing of these fabrics requires gentle treatment so that the configuration of piles is maintained in desired manner. Tendulkar et al (1995) studied the prevailing practices of bleaching process of terry towels and found that generally process flow given as under is followed:

i) Enzyme/acid treatment for de - sizing
ii) Washing
iii) Neutralization with acetic acid
iv) Bleaching in H2O2, Caustic and Soda Ash
v) Washing
vi) Softening
vii) Drying

Kiers, winches, open tubes, etc., are conventionally used for de - sizing and bleaching for most type of fabrics. In these equipments, no specific arrangement was installed for treatment of delicate fabrics like terry towels. Surveys conducted for the practices of chemical processing in decentralized sector have revealed that still raw methods are in use (Gujar et al 1992, Patel 1998, Gangopadhyay et al 1999). But after the invention of soft flow machine the effectiveness of chemical processing in terms of both cost and quality is increased a lot.

In addition to soft flow machines, development of continuous dyeing range enhanced significantly the productivity and quality of terry fabrics and tubular knits (Omez 1980).

Mahale et al (1990) determined the quality of terry structure in terms of loop density, height, and the tightness of the weave. Absorbency of various terry fabrics is assessed in terms of sinking time, water up take, and wick up methods. Except for the fabrics with loops only one side, other terry weaves were found suitable for wear quality and absorbency.

Patel (1998) investigated the methods involved in terry towels dyeing which includes such processes as side hemming grey fabric, bleaching, drying in open width, dyeing, washing, wet-on-wet finishing, weft straightening, and final drying and batch wise dyeing in rope form which involves scouring, bleaching and dyeing in soft flow machine and final drying with pile lifting. Advantages of weft straightening during pad batch dyeing include no batch variations, little fabric shrinkage and lower water and steam consumption. Advantages of soft flow system include lower investment costs, softer towels, lower dyeing cost, shorter process time and low labour cost.

Teli et al (2000, 2002) investigated the effect of different kinds of softeners and process of softening on functional properties of terry fabrics. Researchers evaluated four softeners with respect to fabric softness as well as other properties such as water uptake, sinking time, bending length, wicking height, whiteness and hand. Researchers observed that 40oC was an optimum processing temperature. The terry soft - 478 softener exhibited the best overall performance.

11. CONCLUSION

Above discussed research related to various technological developments of terry looms as well as related to the effect of chemical and mechanical process parameters on functional properties of towels has revealed that softer and high water absorbent towels can be manufactured by employing variety of methods. All the methods and techniques being invented have their own contribution in enhancing the functional or aesthetic properties of towels. However it is observed that characteristics of pile warp yarn play a greater role than the rest in determining the softness and water absorbency of terry towels. Softness of terry towels goes hand in hand to the softness of pile warp yarn. Softness of yarn basically depends on two factors, of which, first is type of fibre, and its properties. The other is twist inserted in yarn to bind the fibres together. Many researchers studied the effect of these factors on functional properties of towels. Low twist yarn when used in pile warp, produces softer and better water absorbent towels.

Acknowledgement

We express a deep sense of gratitude to Dr. J.V.Rao, Director, NITRA, Ghaziabad for his constant inspiration, valuable suggestion and giving permission to publish this paper.

References:

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About the author:

Umesh Chand Sharma completed his AMIE in Textile Engineering in 1990. Presently, he is working with Northern India Textile Research Association (NITRA), Ghaziabad as Principal Scientific Officer. He has a total experience of 22 years in working with industry and research organisation.

He is mainly involved in handling research projects sponsored by various government agencies and also in-house projects in the areas of process, product, and machine development.

Moreover, he is actively engaged in rendering consultancy to industry in different areas like maintenance management, quality management, resolving ad hoc problems related to quality and productivity, techno-economic viability study, valuation of plant and machinery, vetting of project proposals, and project report preparation for modernization and expansion.

Email: umeshnitra@rediffmail.com


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