EFFECT OF SEAM ON DRAPE COEFFICIENT

5.1 Introduction

5.1 .I Materials

5.2 Methods

5.3 Results and Discussions

5.3.1 Effect of the Direction of Seam on Drape Coefficient

5.3.1.1 Warp Direction Seam

5.3.1.2 Weft Direction Seam

5.3.1.3 Radial Seam

5.3.2 Effect of the types of seam on the Drape Coefficient

5.3.3 Effect of Seam Allowance on Drape Coefficient

5.3.4 Effect of Stitch Density on Drape Coefficient

5.3.5 Effect of Sewing Thread on Drape Coefficient

5.3.6 Effect of Seam on each Fabric

5.3.6.1 Sample 1

5.3.6.2. Sample 2

5.3.6.3 Sample 3

5.3.6.4. Sample 4

5.6.3.5 Sample 5

6.0 C0NCLUSK)NS

EFFECT OF SEAM ON DRAPE COEFFICIENT

5.1 INTRODUCTION

Fabric drape had attracted the attention of many researchers because of

the attempts to realize the clothing system by introducing the fabric properties,

in which fabric drape is the key element. It is obvious that fabrics have to be

stitched together for a garment to be formed. The seams of the garment affect

the fabric drape greatly. It is impractical, to work on the garment system without

the consideration of seams and the methods of assembling of fabrics into

garments.

5.1.1 MATERIALS

The materials are the described in the Chapter 3.

5.2 METHODS

For the present study, Cusick Drapemeter was used for evaluation of

fabric drape in terms of drape coefficient. Singer electrically operated sewing r

machine, sewing needle number 11, cotton 9 d lyester spun threads with

yam count 80 were chosen for sewing. The stitch density was varied as 4,6

and 9 stitcheslcm. Stitch tension was maintained constant on both the sides of

the fabric. All test fabrics were placed in the standard testing atmosphere for 24

hours before test. Materials used were woven fabrics.

5.3 RESULTSAND DISCUSSION

5.3.1 Effect of the Dlrectlon of Seam on Drape Coefficient

Investigation of effect of direction of seam on drape coefficient was

considered for the present study. Generally, when a fabric is cut for designing a

garment it should be cut along the warp direction, 2s it is strong and more

durable. Whenever a paper pattern is made the warp direction otherwise known

as straight grain is always marked in the paper.

From the literature survey it was observed that only limited number of

papers have been published on seam and drape coefficient. So, a

comprehensive study was initiated to investigate on this area

5.3.1.1 Warp Direction Seam

This denotes the seam, which is sewn parallel to the selvedge of the

fabric. From the study it was found that the warp direction seam had higher

drape coefficient. In turn the seam on the warp direction reduces the

drapeability of the fabric considerably. When compared to the wefi direction

warp direction seam was found to be higher; this may be due to the number of

warp threads, which is higher than that of the weft threads in fabric count. More

the number of warp threads higher the bending rigidity of a fabric, which in turn

affects the drapeability of the fabric.

5.3.1.2 Weft Dltectlon Seam

There was an increasing trend in the drape coefficient when seam was

applied to the fabric. But when compared to the warp direction seam, the wefi

direction seam had lesser drape coefficient, which means better drapeability

than that of the warp direction seam fabric. The reason is that the number of

weft threads in the fabric is lesser than that of the warp.

5.3.1.3 Radial Seam

Radial seam is popular in women's attire. It was found that the drape

coefficient decreased in the radial seam when compared to that of the fabric

without seam. This study is in good agreement with the study conducted by

Suda and Nagasaka [37, 381. The decrease is due to the disturbance caused

near the perimeter of the circular specimen. The radial seam was produced by

attaching extra material (but maintaining 30 cm diameter) along the perimeter,

which increased the weight due to seam fixing and stitching along the

perimeter, thereby reducing the drape coefficient. Drape is the fall of fabric on

its own weight when supported at one part. This may be the reason for the

reduction in the drape coefficient. Radial seam was tested test with only one

type of seam namely plain seam, as edge stitched seam is not applicable for

the radial seam

5.3.2 Effect of the types of seam on the Drape Coefficient

A simple and commonly used plain seam was used as one type.

Secondly, edge finished seam was considered, as this seam is used for holding

the seam in place and it is the second largely used seam for garment

construction. Though there was the increase in the drape coefficient when

compared to the fabric without seam, the plain seam fabrics had lesser drape

Table 5.1

Drape coefficient with Radial seam

Sample No.

1

2

3

4

5

Original Drape coefficient

78.00

68.29

75.72

60.36

67.77

Drape coefficient with radial seam

76.46

65.24

74.94

58.31

62.27

Fig 5.1

Drape Coefficient with Radial Seam

1 2 3 4 5

Sample

coefficient than that of the edge stitched seam fabric. The trend was similar in

both warp and weft direction.

The reason is that, for the plain seam only one stitch is applied on the P

fabric, but for the edge stitched seam three stitches are required. Therefore as

the number of row of stitches increases, the drape coefficient also increases.

The number of rows of the stiiches causes stiffness in the stitched area thereby

affecting the bending rigidity of the fabric in that particular area; this in turn

affects the other part of the fabric leading to poorer drapeability. It can be

concluded that unless necessity arises it is always better to minimize the

number of rows of stitch while constructing a garment.

5.3.3 Effect of Seam Allowance on Drape Coefficient

Seam allowance is another area, which needs to be analysed while

studying the effect of seam on fabric drape. Seam allowance varies with the

type of garment and on where the seam is applied on the garment. Normally

0.5 cm to 2 cm seam allowance is popular while constructing a garment. The

effect of this need to be analysed, so, four variation of seam allowance was

studied on various fabrics. The study reveals that initially with 0.5 cm seam,

there is an increasing trend in drape coefficient. But with a 1 cm seam

allowance there was a drop in the drape coefficient. Froml.5 cm onwards as

seam allowance increased the drape coefficient also increased (fig).

The reason for initial increase in drape coefficient is that the fabric with

seam has higher drape coefficient than that without seam. The 0.5 cm seam

allowance is a n a m seam allowance making the seam applied area to be very

stiff thereby obst~ding the bending capacity of the fabric, disturbing the fall of

the other part of the fabric. The decrease in the drape coefficient with seam

allowance of 1 cm is due to the bmader seam, which im~mves the bending of

fabric at that area, in turn appreciably decreasing the drape coefficient of the

fabric. For seam allowance 1.5 cm, it was noted that the increase in seam

allowance, increased the drape coefficient. This is due to the fact that

increased length in seam almost becomes a double-layered fabric at the area of

the seam. Thus, it can be concluded that Icm seam allowance is the ideal one

which cause less disturbance in the drape value.

5.3.4 Effect of Stitch Density on Drape Coefficient

Stitch density is another important factor, which needs to be analysed. In

the present work three varied stitch densities were used and their effect on

drape coefficient was studied. The stitch density considered for the present

study are 4,6 and 9 stitch per centimeter and they are termed as low, medium

and high respectively. Fmm low to medium stitch density there is a dmp in the

drape coefficient, and there was an increase in drape coefficient for high stitch

density.

An analysis on the behaviour of the fabric showed that the fabrics with

low stitch density, where the stitches are longer, caused disturbance in the

fabric structure. The long stitches caused the fabric to be stiffer in the line of

the stitch applied. As far as the medium stitch density is concerned the stitch

length goes hand in hand with the thread intersection of the fabric, so the fabric

structure is less disturbed, which is reflected in the decrease in the drape

coefficient when compared to the low stitch density. The study also established

that there is an increase in the drape coefficient with high stitch density when

compared to medium stitch density. The reason may be that the length of the

stitch is very small which damages the fabric structure causing the stiffness in

that area where stitch is applied in the fabric. It can be concluded that 4 stitch I

cm is found to be the optimum stitch density, which causes less hindrance to

drape coefficient of a fabric.

5.3.5 Effect of Sewing Thread on Drape Coefficient

For the present study cotton and spun polyester sewing threads were

used to finish the seam. The comparison of the effect of sewing thread was

done with medium stitch density for warp and weft direction seam. This was

applied to both plain and edge finished seam. Generally, it was observed that

finishing the seam with polyester thread had lower drape coefficient than for the

fabric which was used to finish the seam with cotton thread. But the difference

was not significant. It can be concluded that the variation in sewing thread

does not make much difference in the drape coefficient.

5.3.6 Effect of Seam on each Fabric

5.3.6.1 Sample 1

Figures 5.1, 5.2, 5.3, and 5.4 show the drape coefficient of sample 1. It

is interesting to note that variation in the seam allowance and difference in

stitch density showed an increase from initial value i.e., drape coefficient of the

fabric without seam. Thereafter the drape coefficient decreased with increase in

seam allowance and stitch density and then increased. It was observed in the

drape coefficient of warp direction plain seam with high stitch density of fabric it

showed a gradual increase unlike the other cases. This may be due to the fact

that the warps count of the fabric Sample 1 is very highi, &e high stitch density

should have obstructed the bending rigidity of the fabric, which in turn is

reflected in the drape coefficient. The same reason is depicted in the Fig 5.2,

which exhibits a steep increase in the drape coefficient curve for a high stich

density seam. Regarding the comparision of sewing thread the Polyester cotton

thread showed a slightly improved drape coefficient when used with cotton

threads. As usual the warp direction seam had higher drape coefficient than

weft direction, which was visible in the Fig 5.3.

5.3.6.2. Sample 2

Table 5.2 shows the detail of the sample II drape behaviour with seam in

different variations. Generally, the sample II drape behaviour follows the general

trend as explained earlier. But in Fig 5.7, it is interesting to note that there is a

steep fall in drape coefficient for weft direction plain seam with 0.5 cm seam

width at medium stitch density, unlike the other types. This may be because the

fabric is plain weave dress material, which can withstand the least seam

allowance possible than that of the suiting and shirting material.

' Ornotropic structure of the fabric, warp count is higher than the weft count. Especially, for thicker fabrics, warp bend in^ stiffness is much greater than the weft 1401.

95

Tabl

e 5.

2. D

rape

Cd

cie

nt w

ith S

eam

S

AM

PLE

1

SAMPLE l Fig 5.2

Seam Allowance Vs Drape Coefficient

ESS weft llowl Ps warp (l"' I - PS weft ( m d )

ESS weft (mod) Ps waw I 0 0 0 5 1 0 1 5 2 0 / - 4 - ESS warp (med)l

- ESS warp (high! I - - -

Seam width (cms)

Fig 5.3 Stitch Density Vs Drape Coefficient

(SA - 2cm 8 1.5cm)

- PS weft (hlgh) - PS warp (high) - ESS weft (high)

83 5

83 0

82 5

185- *---*-•

Q 785- - PS warp (2cms) 780- -A- ESS weft (2cms) 7 7 ~ 1 , . , . -t ESS warp (2cms)

0

SMch Denrlty (Slcm) PS warp (1.5cms) --c- ESS wefl(1.5crns) -t ESS warp (1 5cms)

Fig 5.4 stitch ~ensity vs ~ m p e coefficient

(SA- lcm & O.!km)

2 4 8 8 lo 4

Stitch Density ( Wcm)

-* - PS weR (lcm) - PS warp (lcm) -ESS weR (Icm) -+- ESS warp (Icm) t- PS weft (0.5cm)

PS warp (0.5cm) + ESS weR (O.5cm) - ESS warp (0 5cm)

Fig 5.5 Comparison of Sewing Thread

P S weR PIC P S w e R d t o l l I P S warp PIC P S w a r p m n o n I ESS wen PIC I=] ESS waR cotlon

ESS warp PIC ESS warp wnon

SAMPLE II Fig 5.6

Seam width Vs Drape Coefficient

& , . , , , . , . , < 0 0 0 5 I0 IS 2 0

Seam Width (cms)

--c low PS.wR Ir

4- low PS.warp --e low ESS.weR -low ESS.warp 4 med PS.weR

+ - med PS.warp med ESS.weR med ESS.warp

-c high PS.weR --+-high PS.warp +igh ESS.weR ---high ESS.warp

Fig 5.7 Stitch Density Vs Drape coefficient

( SA- 2cm & 1.5 cm)

- PS warp (2cms) -+- ESS w& (2cms) - ESS warp (2cms)

WO- - PS Weq1.5 cms) PS warp ( I .5cms)

Stitch Density (Ycm) +- ESS wefl(1 .5cms)

Fig 5.8 Stitch Denslty Vs Drape Coefficbnt

(SA - 1 cm 8 0.5 cm)

Fig 5.9 Comparison of Sewing Threads

mc: 5 m2- ;; --)- PS wefl (lcm)

-+- PS warp (lcrn)

8 z 0 6as

-A- ESS wefl (lcm) - ESS warp (lcm)

6a4 e; 1- ,\y,, -+ PS well (0.5cm) ed 2 PS warp (0.5cm) edo + ESS wefl(0.5cm)

0 2 I 6 I " --c ESS warp (o.!jcm) Smch Density (slcm)

SAMPLE Ill Fig 5.10

Seam Width Vs Drape CoofACient

7s-l , . , , , , , , , 0 0 0 5 10 1 5 2 0

Soam Width (ems)

- low PS.weR +- low PS.warp A low ESS.weR -low ESS.warp --+- med PS.wefi - 4-- med PS.warp

med ESS.weft med ESS.warp

-+-high PS.weR --e-high PS.warp -+ -h igh ESS.weft - -high ESS.warp

Fig 5.11 Stltch Density Vs Drape Coefficient

(SA -2cm 8 1 .5 cm)

- PS Weft (2crns) - PS warp (2cms) --c ESS wefl(2cms) - ESS warp (2cms) -+- PS weft(1.5 cms)

PS warp ( I .5cms) -+ ESS weft (1 .5cms) - ESS warp (1.5cms

Fig 5.12 Stitch Density Vs Drape Coefficient

(SA-lcm 8 O.Scm)

--c PS wen (Icm) - PS warp (Icm) -A- ESS weft (Icm) - ESS warp (Icm) -+- PS weR (0.5cm)

7504 , . , . , . , . , . , o 2 1 (I 8 10 PS warp (0.5cm)

4.- ESS wen (0.5cm) Stitch Ms i ty (dcm)

--t ESS warp ( 0 . 5 ~ 1 )

Fig 5.13 Comparison of Sewing Threads

# PS wsn (PIC) PSweR~co(lml

I PS warp (PIC) PS warn IaMicm) I ESS &n'(PIC) '

0 ESS wsn (colbn) 1 ~ E ~ w F ' O 1 l ESS warp (*)

OD-

OB -

,I

1: s 2

ri m i

SAMPLE IV Fig 5.14

!ham Width Vs Drip. Codficlent

-low Ps.weR --e low PS.warp - low ESS.weR

0 0 05 1 0 I5 2 0 -low ESS.warp + rned PS .weR

Soam Width ( m s ) -- rned PS.warp rned ESS.weR med ESS.warp

-high PS.wefl --+-high PS.warp *igh ESS.weR --+-high ESS.warp

Fig 5.15 Stitch Density Vs Drape Coefficient

(SA- 2cm 8 1.5 cm)

- PS WeR (2cms) - PS warp (2cms) + ESS weft (2cms) - ESS warp (2cms) -t PS wefql.5 ems)

PS warp (1 .!jcnla) - ESS wall ( 1 . 5 m ) - ESS warp (1.5wns)

Fig 5.16 Stitch Density Vr Drape Coefficient

(SA- Icm & O.Scm)

-- - 9 5 1 , . , . , , , . , , ,

0 2 4 e 8 10

Stitch Density (Slcm)

--c PS weR (lcm) - PS warp (lcm) --e- ESS weft (lcm) - ESS warp (lcm) - +-- PS weft (0.5cm)

PS warp (0.5cm) ESS weR (0.5cm)

--t ESS warp (0.5cm)

Fig 5.17 Comparison of Sewing Thread

PS weR (PIC) PS vmR (conon) PS warp (PIC) - PS werp (cotton) ESS weft (PIC) 0 ESS weft (cotton)

ESS warp (PIC) ESS warp (cotton)

SAMPLE V Fig 5.18

Seam Width VS Drape coefficknt

4 rned PS.werp rned ESS.wefl rned ESS.warp - high PS.weR high PS.warp

--* - high ESS.wefl + high ESS.warp

Fig 5.19 Stitch Density Vs Drape Coefficient

(SA- 2cm & I .5 cm)

a 1 0.0 0 5 1 0 1.5 2.0

Seam wldth (ems)

+low PS.wefl l0wPS.warp

A lwESS.wefl T low ESS.warp * rned PS.weft

76 - 74 -

a PS warp (2cms) 00- - - ESS wefl(2cms)

- t ESS warp (2cms) 0 7 4 , . , . , .

0 2 4

Stltch Denrlty (Slcm) PS warp (1.5cms) ESS wefi (1.5cms)

I f

L.j f - A - t ESS warp'(2cmi)

07 , . , . , . , . o 2 4 6 t- PS wefl(l.5 cms)

Stltch Denrlty (Slcm) 4 PS warp (1.5cms) ESS wefi (1.5cms)

Fig 5.20 Stitch Density Vs Drape Coefficient

(SA- lcm L 0.5 cm)

- PS weft (Icm) PS warp ( I cm)

A ESS weft (lcm) 8 7 A , , , , , , , , . , -t ESS warp (Icm)

o 2 4 6 B '0 PS weft(0.5cm) Stitch Density (Slcm) 4 PS warp (0.5cm)

ESS weft (0.5cm) * ESS warp (0.5cm)

Fig 5.21 Cornparision of Sewing Threads

PS weft (PIC) PS weft (mtton) PS warp (PIC) PS warp (cotton) ESS wen (PIC)

L7 ESS waR (cotton) ESS warp (PIC) ESS warp (cotton)

5.3.6.3. Sample 3

In Sample 3, when the seam was introduced there was no significant

change except for a very steep increase in the drape coefficient (Fig 5.9, 5.10,

5.1 1 & 5.12). Otherwise the trend was the same as discus*hd earlier.

5.3.6.4. Sample 4

Fig 5.14 shows the stiich density vs drape coefficient for 2 and 1.5 cm

seam width. It can be seen that weft direction plain seam with 1.5 cm seam

width showed only increasing trends. The rest of the variable trends in drape

coefficient were the same as the general trend.

002389

5.3.6.4. Sample 5

Sample 5 followed the general trend in drape behaviour without any

notable changes in the trend2.

6.0 CONCLUSIONS

The conclusions are as follows:

1. There was an increase in drape coefficient when seam was introduced in

the fabric.

'The warp and weft bending stiffness are similar in Isotropic structure of a fabric [40].

101

2. Drape coefficient of warp direction seam in the fabric was higher than the

wefl direction seam.

3. Drape coefficient of the fabric with seam allowance of lcrn was found to

be the lowest among the four seam allowances.

4. Fabric with medium stitch density had the lowest dkpe coefficient.

5. The fabric with radial seam exhibited a decrease in the drape coefficient

when compared to the fabric without seam.