Source: Textile Review

Drape, one of the most important properties of fabric, has played significant role in providing graceful aesthetic effects in garment. Study of historic costumes of India, Egypt and Rome reveals that when stitch craft was not known to man, drape of fabric was used as device of special adornment in the garment. This article discusses factors affecting draping quality of fabric as well as its measurement.


Aesthetic appeal of apparel has always been important for men. Drape, one of the most important properties of fabric, has played significant role in providing graceful aesthetic effects in garment. Study of historic costumes of India, Egypt and Rome reveals that when stitch craft was not known to man, drape of fabric was used as device of special adornment in the garment. This article discusses factors affecting draping quality of fabric as well as its measurement.


Drape aspect of fabric has been focus of research in fabric engineering for many years. Although drape is a subjective quality as it pertains to appearance, attempts have been made to objectively define and measure drape in fabric form.


Drape is the ability of a fabric to fall under its own weight into wavy folds of different nature. Fabric drape can be evaluated objectively as well as subjectively.


Objective assessment of drape


Drape of fabric can be studied by objective assessment and this is done with the help of an instrument. Monoplanar test and multiplanar test are used to measure fabric drape quantitatively.


Monoplanar test


Monoplanar test is based on measurement of fabric stiffness. Stiffness is the key factor in the study of drape. Quantitatively stiffness of fabric is measured in terms of the bending length or flexural rigidity. Stiffness tester based on cantilever principle is used to measure bending length. A strip of fabric is pushed forward untiI gravity causes the strip to bend to a prescribed length. This approach is still used today in analyzing drape properties for strip geometries.


Multiplanar test


Stiffness values are measured only in one direction (either warp or weft) at a time where as drapability is the result of interaction between warp way and weft way characteristics of fabric.


An instrument known as drapemeter, which is capable of distorting the fabric in all three directions is used to evaluate drape quantitatively. Drapemeter measures three dimensional fabric drape due to gravity. Circular drapemeter has been most widely used to study fabric drape and factors affecting it.


The experimental method generally involves hanging fabric specimen of 15 cm. radius over supporting disc of 9 cm. radius. Unsupported area drapes down under its own weight. Drape is measured as drape ratio or drape coefficient which theoretically varies from 0 to 100.


Subjective Assessment of Drape


Drape can be assessed subjectively. Fabric assessment is often done by handling the fabric and verifying how it falls into folds and how regular these folds are. Subjective evaluation of garment drape is done by evaluating the garment for its appearance and aesthetic value by judges.


Factors Affecting Drape Of Fabric


Drapability of a fabric is combined effect of several factors such as stiffness, flexural rigidity, weight, thickness etc. Stiffness, an attribute of fabric hand is one of the most important factors determining draping quality of fabric e.g. soft fabric drapes closer to the body forming ripples whereas stiff fabric drapes away from the body. Stiffness of fabric itself depends upon geometrical parameters of the fabric.

The draping quality of fabric is affected by the stiffness of the fiber and the yarn, the size of yarn, thread count and method of construction. The handle of cotton fiber is hard and stiff whereas wool has soft to medium handle. The handle of polyester is medium to hard. Yarn stiffness is controlled by fiber stiffness and also by arrangement of fibers in yarn. Highly twisted yarns make fabric stiffer. When yarns are woven into fabrics, a wide range of stiffness is possible depending upon the extent to which free movement of fiber is inhibited by fabric structure. Fabrics made from heavy, coarse yarn and in dense construction do not drape well. Fabrics that have long floats in weave can be more flexible, bending more easily and improving draping quality. If at the same time, fabrics are made from filament yarns with little twist, the draping quality is enhanced more. Drape ratio of woven and nonwoven fabrics differ because of the difference in their method of construction.


Finishing agents can be used to alter fabric hand and change draping quality. Starching gives body, weight, smoothness and stiffness to fabric. Resins can modify hand of fabric and produce a variety of effects .Polyethylene emulsion, silicone softner, ionic and non ionic softner impart softness. Resiliency can be imparted to a fabric by applying styrene/butadiene copolymer emulsion. Polyvinyl acetate emulsion and their copolymer impart body, weight and produce full, firm hand or full, soft hand or stiff hand.


Numerous studies have been conducted to study factors affecting draping quality of fabric. It has been proved that major mode of deformation in drape is fabric bending. The other mode of deformation is the sheer of fabric. Cussick(1965) found that bending length and sheer stiffness have high correlation with drape coefficient. Sudnik (1972) studied factors which are related to drape. These are bending length, fabric weight and shear properties.


When yarns are woven into fabrics, a wide range of stiffness is possible depending upon the extent to which free movement of fiber is inhibited by fabric structure. Fabrics made from heavy, coarse yarn and in dense construction do not drape well. Fabrics that have long floats in weave can be more flexible, bending more easily and improving draping quality. If at the same time, fabrics are made from filament yarns with little twist, the draping quality is enhanced more. Drape ratio of woven and nonwoven fabrics differ because of the difference in their method of construction.


Mooreka (1976) analyzed the relation between drape coefficient and mechanical properties. He found that bending rigidity and weight are the most determinative parameters of drape. The actual draping at any point in a garment depends upon the total weight suspended from that point. Chaudhary (1980) conducted a study to predict drape coefficient by weaving parameters. He stated that drape is closely related to the weaving parameters. Zeong & Philips found that fabric cover has a large effect on fabric drape because of its effect on bending rigidity. Yarn interaction and crimp, which are determined by weave structure, also influence the drape. Similarly fabric tightness also influences the drape. Chen and Govindraj (1996) observed that young's modulus, shear modulus, thickness have varying effect on extent of fabric drape but poisson's ratio does not have appreciable effect on drape. Pant (2004) found substantial increase in drape coefficient of fabrics finished with acrylic and polyvinyl acetate finishes as a result of increase in stiffness. In case of silicone finish, drape coefficient decreased slightly.


It is evident that drape of a fabric is affected by type of fiber, yarn, fabric structure, method of construction and finishing. By manipulating these parameters fabrics of different draping quality can be manufactured & used for creating garments of different styles


References


  1. Cussick, G. E. The dependence of fabric drilpe on bending and shear stiffness. journal ofTextile Institute. 56, 596,1965.
  2. Chaudhary, C.K. Prediction of drape coefficient by weaving parameters. Unpublished Masters Thesis, Faculty of Technology and Engineering, M.5.University of Baroda,1980.
  3. Chen, Band Govindraj,H. A parametric study of fabric drape. Textile Research Journal. 66(1),17-24,1966.
  4. Mooreka,H. and Nlwa M. Relation between drape coefficient and mechanical properties of fabric, journal of Textile Milch, 50cl. japan. 22(3),63-67,1976.
  5. Sudnik,Z.N. Objective measurement of fabric drape. Textile Institute and Industries. 10, 14-18, 1972.
  6. Pant,S. Wool and Wool Blend Finishing. Navjeewan Publication, Newai,2004.
  7. Shenai,V.A. Technology of Textile Processing. Sevak Publications, Mumbai, 1996.


About the Author


Suman Pant is associated with Faculty of Home Science, Banasthali University


Originally published in Textile Review: February 2010