circular support over which a specimen of the fabric in form of a circular piece is placed with an annular section overhanging the support. The horizontal area covered by the shadow left by the overhanging portion of the fabric is determined and compared against area to obtain the drape coefficient.
Drape is one of the subjective performance characteristics of fabric that contributes to aesthetic appeal. It is a complex property involving bending and shearing deformations. One of the methods of determining the drape characteristics in which both the warp and weft way characteristics interact to produce a graceful folding uses a circular support over which a specimen of the fabric in form of a circular piece is placed with an annular section overhanging the support. The horizontal area covered by the shadow left by the overhanging portion of the fabric is determined and compared against its actual area to obtain the drape co-efficient.
The “HIROSHIMA” Drape meter consists of a circular specimen support, an electric lamp to give off light, and an exposing and developing arrangement using ammonia process paper to determine the area covered by the shadow of the test specimen. The circular specimen support is made out of cast aluminium and is fixed over a clear acrylic sheet. The sheet is hinged at one end and can be lifted for placing the ammonia process paper for exposure. The paper is kept below the acrylic sheet on a resilient surface so that it is in close contact with the sheet when it is horizontal.
The specimen holding and paper exposing arrangement is kept inside a sheet metal exposure chamber. The electric lamp is fitted at the upper end of the chamber so that light ray coming from it is intercepted by the test specimen. The rays, which are not intercepted, fall on the paper and expose it, thus giving a demarcation between exposed and unexposed areas. The chamber has a close fittings door. It has ventilation doors near its bottom and top for keeping it cool.
An ammonia vapour-developing chamber in which the exposed paper is kept for developing is provided below the exposing chamber. The chamber has a close fitting door arrangement to keep ammonia hydroxide to create a suitable atmosphere for developing the print. The test specimen is kept over a welded wire mesh platform to ensure a uniform developing.
The outside of the apparatus is finished in dark grey synthetic enamel to give it a corrosion resistant finish.
A metal template of 250mm diameter have a central hole for marking and cutting the test specimens, a specimen pressing disc, one hundred sheets of ammonia process paper, and one bottle of ammonia hydroxide are supplied as standard accessories.