14 July 2012
What is Drape? | Cusick Drape Test
Drape
Drape
is the term used to describe the way a fabric hangs under its own
weight. It has an important bearing on how good a garment looks in use.
The draping qualities required from a fabric will differ completely
depending on its end use, therefore a given value for drape cannot be
classified as either good or bad. Knitted fabrics are relatively floppy
and garments made from them will tend to follow the body contours. Woven
fabrics are relatively stiff when compared with knitted fabrics
so that they are used in tailored clothing where the fabric hangs away
from the body and disguises its contours. Measurement of a fabric s
drape is meant to assess its ability to do this and also its ability to
hang in graceful curves.
Cusick Drape Test
In the drape test the specimen deforms with multi-directional curvature and consequently the results are dependent to a certain amount upon the shear properties of the fabric. The results are mainly dependent, however, on the bending stiffness of the fabric.
In the test a circular
specimen is held concentrically between two smaller horizontal discs and
is allowed to drape into folds under its own weight. A light is shone
from underneath the specimen as shown in Fig. 10.4 and the shadow
that the fabric casts, shown in Fig. A, is traced onto an annular piece
of paper the same size as the unsupported part of the fabric specimen.
The stiffer a fabric is, the larger is the area of its shadow compared with the unsupported area of the fabric. To measure the areas involved, the whole paper ring is weighed and then the shadow part of the ring is cut away and weighed. The paper is assumed to have constant mass per unit area so that the measured mass is proportional to area. The drape coefficient can then be calculated using the following equation:
The higher the drape coefficient the stiffer is the fabric. At least two specimens should be used, the fabric being tested both ways up so that a total of six measurements are made on the same specimen. There are three diameters of specimen that can be used:
• A 24cm for limp fabrics; drape coefficient below 30% with the 30cm sample;
• B 30cm for medium fabrics;
• C 36cm for stiff fabrics; drape coefficient above 85% with the 30cm sample.
Cusick Drape Test
In the drape test the specimen deforms with multi-directional curvature and consequently the results are dependent to a certain amount upon the shear properties of the fabric. The results are mainly dependent, however, on the bending stiffness of the fabric.
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| Drape Test |
The stiffer a fabric is, the larger is the area of its shadow compared with the unsupported area of the fabric. To measure the areas involved, the whole paper ring is weighed and then the shadow part of the ring is cut away and weighed. The paper is assumed to have constant mass per unit area so that the measured mass is proportional to area. The drape coefficient can then be calculated using the following equation:
The higher the drape coefficient the stiffer is the fabric. At least two specimens should be used, the fabric being tested both ways up so that a total of six measurements are made on the same specimen. There are three diameters of specimen that can be used:
• A 24cm for limp fabrics; drape coefficient below 30% with the 30cm sample;
• B 30cm for medium fabrics;
• C 36cm for stiff fabrics; drape coefficient above 85% with the 30cm sample.
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| Drape test top view of draped fabric |
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