The inherent properties such as strength,
permeability, thickness, etc all are considered to be objective performance
characteristics. They can be measured and evaluated in quantitative terms on the
basis of scientific knowledge, independent of personal preferences and
There are certain equally important subjective performance characteristics,
which are evaluated at least in part by personal reaction. These can be
expressed only in relative qualitative terms although quantitative physical
parameters in part govern the subjective rankings. These three important
subjective tests are hand or handle, drape and lustre. Handle describes the feel
of the material and qualitatively includes such terms as stiff, limp, hard,
soft, rough and smooth. Flexibility is the ease with which a specimen may be
bent. In certain cases the weight of the material acts to bend it about an axis.
Rigidity is the measure of resistance offered by the specimen to bending. It is
a measure of stiffness. Drape differs from rigidity in that the weight of
material in-fluences a deformation at some angle to the line of action. The
article discusses the issues covering drape of fabric with emphasis on two
aspects: One is the stages of developments in drape meters & their
limitations. The other is the recent developments in drape measuring
instruments, their advantages and modern features.
Drape of fabric
In 1950, C C Chy and others defined(5) the drape as - drape and
drapability are terms for that property of textile materials, which allows a
fabric to orient itself into graceful holds or pleats when acted upon by force
of gravity. Hence a fabric is said to have a good draping qualities when the
configuration is pleasing to an eye.
In 1965 G E Cusick defined(6) the drape as-it is a description of the
deformation of the fabric produced by gravity when only part of it is directly
According to IS-8357/1977 the drape is defined as
the extent to which a fabric
will deform when it is allowed to hang under its own weight. According to
BS-5058/1973 the drape of fabric is defined in similar way.
According to BS-5058/1973, it is defined as the percentage of the total area to
an annular ring of fabric obtained by vertically projecting the shadow of the
According IS-8357/1977, it is defined as the area covered by the shadow of the
draped specimen expressed as percentage of the area of the annular ring of
The extract(7) of BS 5058/1973:
A circular fabric specimen is held concentrically between smaller horizontal
disc and an annular ring of fabric is allowed to drape into folds around the
lower supporting disc. The shadow of the draped specimen is cast onto an annular
ring of paper of same size as the unsupported part of the fabric specimen. The
outline of shadow is traced onto the ring of paper, the mass of which is then
determined. The paper is then cut along the trace of shadow and the mass of
inner part representing the shadow is determined. The drape co-efficient is
calculated from two masses.
The extract(8) of IS 8357/1977:
A circular fabric specimen is sandwiched between two horizontal discs of smaller
diameter and the unsupported annular ring of fabric is allowed to hang down
under the action of gravity. A plan projection of the contour of the draped
specimen is recorded on light sensitive paper. The drape pattern obtained is cut
along the outline and its area determined gravimetrically. The drape
co-efficient is calculated as the ratio of projected area of the drape specimen
to its theoretical maximum.
Significance of drape measurement(1,2,3,4)
The drape co-efficient is a measure of drape. It is a single number with a
theoretical maximum of hundred and minimum of zero. The specimen deforms with
multi-directional curvature and result is therefore dependent upon the shear
stiffness of the fabric in addition to bending stiffness.
Stages of developments of drape measuring
||M I T Drape-o-meter
||Original F R L Drape Meter
Improved F R L Drape Meter
||Cusick’s Drape Meter
||BTRA Drape Meter
||Developments by Marathwada University(10)
Drape measurement can be employed for study of
the effects of fabric geometry, chemical processing treatment and finishes for
woven and knitted fabrics, certain qualities of nonwovens. Drape co-efficient
can also be used as an index for control of batches in production. The drape
measurement is significant in garment industry where the fabric is selected
according to the end use. The drape is one of the most important properties in
selection criteria of fabric of garment industry. For eg, the fabrics for
suiting should possess fewer drapes and the fabric for shirting and ladies wear
should possess high drape.
The details of M I T Drape-O-Meter, Original F R L Drape Meter(5),
Improved F R L Drape Meter(5), Cusick's Drape Meter(6) and
BTRA Drape Meter(9) are available in the given references. It is
beyond the scope of this publication to describe the same. The comparison of the
same is given in Table 1.
Table1: Comparison of Drape Meters (Till 1977)
||F R L (1950)
(dia in CM)
(dia in CM)
|10 cm, 12.5 cm
||Area of draping
||Shadow due to
||Shadow due to
||Drawing of draped
||Light source Used
mercury vapor Lamp (125 w)
Excluding sample preparation Time
In 1993, constructive attempts(10)
were also made by the present author to develop the slightly improved drape
meter, but the development was limited and of academic interest only and not up
to the mark for commercial aspects.
In last decade of 2000 century, lots of improvements were witnessed by textile
and garment industry, thanks to microprocessors, electronics chips and IT
industry. Drape measurement is not the exception for the same as it was then
very easy & accurate to analyse the draped pattern/image with the help of
different sensors. The following are the instruments developed recently.
D H L Drape Meter (According to BS - 5058/1977)
In 2005, the author(11) developed the D H L Drape Meter. The
development was based on BS 5058/1977.
The characteristics of drape of fabric are complex in nature. The instrument is
developed to test the fabric drape in a simple way. The drape is due to the
deformation by gravity of an initially horizontal annular ring of fabric. A
measure of drape is obtained as a single number with theoretical maximum of 100%
and minimum of zero %. The specimen deforms multidirectional curvature and the
result therefore depends upon the shear stiffness of fabric and bending
A circular fabric specimen is held concentrically between smaller horizontal
disc and an annular ring of fabric is allowed to drape into graceful folds
around the lower supporting disc. The outline of shadow is traced on paper and
then its mass is determined. Initially, the weight of paper of 15 cm dia is
determined and the drape co-efficient is calculated.
The instrument consists of three parts, viz, 1. Mirror Unit; 2. Sample Holder;
3. Shadow Tracing Surface.
The parabolic mirror is used to obtain the perfect parallel light beam. The
light source is located at focal point of the said mirror. In absence of fabric
sample, the illuminated light circle is perfectly obtained as of 15 cm dia. The
fabric sample of 15 cm dia is prepared and located in between two supporting
disc of either 6 cm or 9 cm depending upon the quality of fabric. The drape
pattern of fabric is traced on a white paper placed on top glass of an
instrument. The paper is cut perfectly on the drape pattern. The weight of the
paper is noted. The standard weight of 15 cm circular paper is already known.
The drape co-efficient is calculated from these two readings. It is advisable to
test the fabric sample from both sides and minimum two samples per test. The
nodes, ie, curving of folds appeared due to draping also can be noted.
Drape co-efficient (DC%) =
------------------------ x 100
Where, mass of drape pattern (gms) = W
mass/unit area of white paper (gm/cm2) = w
Area of supporting disc of 6 cm dia = a
Area of fabric sample of 15 cm dia = A
Measuring principle - Measurement of shadow area
obtained due to parallel light.
Recording Technique - Manually drawing/tracing of
Test Specimen - 15 cm dia.
Template to prepare sample - 15 cm dia.
Light source - 15 w clear ordinary bulb.
Fuse - Socket type.
Features of the D H L Drape Meter
The instrument is lightweight, handy &
compact; an ordinary salesman can lift it. Moreover, the instrument is
supplied with 5 templates, each one indicating a range of drape
co-efficient and its probable application, say dress material, shirting,
curtains, etc. So during counter sale also, the instrument can provide
the primary judgment of drape. All the time the exact numerical value of
drape co-efficient is not necessary/required. In garment industry, quick
judgment of drape can be obtained from this instrument by using
Comparatively, the initial investment cost is
As the light, which is reflected from the mirror,
is in parallel form, the true shadow will obtain. The problem of
amplification of shadow due to diverging light rays is eliminated in
The ordinary light source is used (15 W clear),
which is easily available at low cost and it is not necessary to put on
the light in advance to warm-up the same.
The re-production of results is excellent.
The other advantages are: Minimum testing time
(15 min), less fabric consumption, less power consumption, dual power
supply, no necessity of dark room, low maintenance cost, few electric
connection and many more.
There may be a human error while tracing the
shadow of drape pattern.
The area available for draping the fabric in
annular ring shape is of 6 cm width in earlier instruments but in this
instrument it is limited to 4.5-cm width.
The range of drape co-efficient is 30% to 90%.
Computerised Drape Meter(12)
D & M Technology Co Ltd, based in Korea, offers a computerised drape meter
under the model name Drape Analyser DM 02.
Basically the instrument is a computerised version of Cusick's Drape Meter. The
detailed information is not made available due to language barrier. Even tough
few clips are collected as below:
An instrument is running under operating system
It is implemented with currently used Drape
Testers and attachments for camera setting.
It uses an image captured by digital camera or
scanner without paper marking & cutting.
It supports 3-dimensional texture mapping to
It reports statistical & shape parameter
analysis as well as drape co-efficients.
It outputs an on-line documentation with drape
It is easy to implement with any existing drape
Expert & academic versions are also
Compatible with Pentium PC at 800 x 600
Number of drape waves or nodes
Drape wave amplitude and wave length
Statistical data: Max & Minimum, Average wave
amplitude & its variance.
The comparison of the above two instruments is
tabulated in table 2.
Table 2: Comparison of Drape Meters (After the year 2000)
||Point of comparison
||D H L Drape meter (2005)
||Computerised Drape Meter
(dia in CM)
(dia in CM)
||Area of draping the fabric
||Can be varied
||Shadow Tracing Technique
||Shadow due to reflection
||Image captured by Digital
||Digital Camera or Scanner
||By Image processing
||Initial Investment Cost
With the summarised details of these instruments, one can conclude that, the
issue of drape testing should be addressed in detail with the help of
available modern technology. The reference study of existing drape meters
till 1977 (Ref Table I) uncovers the limitation of the instruments in terms
of type of output of results, ease of operations, cost, use of special type
of light source, etc. The garment industry will welcome the handy &
user-friendly instrument that can be managed by the counter sales. But the
above-referred instruments are required to be developed for the same.
Hence in recent developments (after the year 2000, Ref Table II) mainly two
distinct alternatives are addressed. Keeping the economical views in mind, D
H L Drape Meter is suitable for garment industry, academic institutes,
shops, malls, factory outlets & many more. The computerised instrument
is also suitable but the constraints in availability of finance may not
allow us to opt for this alternative. In short, facility of drape testing
from user's point of view should be made available at low investment cost.
Grover E B: Handbook of Textile Testing &
Booth J E: Principles of Textile Testing.
Kaswell E R: Textile Fibre, Yarn and Fabric.
Hearl J W S: Structural Mechanics of Fibre, Yarn
& Fabric, Vol I.
Textile Research Jr, 1950, (20), 539.
Journal of Textile Institute, 1665, (56), T 596.
BTRA, Instruction Manual, 1977.
Bhalerao S V: Project Report, Marathwada
Bhalerao S V: Instruction Manual, D H L Drape
The author is a Textile Engineer &
Consultant residing at 1, Devgiri, Ekata Nagar, Gangapur Road, Nashik 422
013. E-mail ID: email@example.com.