The ASIAN Drape meter consists of a circularspecimen support, an electric lamp to give off light, and an exposing anddeveloping arrangement using light sensitive ammonia paper to determined thearea covered by the shadow of the test specimen, and an electric lamp to exposethe ammonia paper to determine the area covered by the shadow of the testspecimen. The circular specimen support is made out cast aluminum and is fixedover a clear acrylic sheet. The sheet is hinged at one end and can be liftedfor placing the ammonia paper for exposure. The paper is kept below the acrylicsheet on a resilient surface so that it is in close contact with the sheet whenit is horizontal.
The specimenholding and paper exposing arrangement is kept inside a sheet metal exposingchamber. The electric lamp is fitted at the upper end of the chamber so thatlight rays coming from it are intercepted by the test specimen. The rays whichare not intercepted fall on the paper and expose it, thus giving a demarcationbetween exposed and unexposed areas. The chamber has a close fittings door. Ithas ventilation holes near its bottom and top for keeping it cool.
An ammoniavapour developing chamber in which the exposed paper is kept for developing isprovided below the exposing chamber. This chamber has a close fitting door andan arrangement to keep ammonium hydroxide to create a suitable atmosphere fordeveloping the print. The test specimen is kept over a welded wire meshplateform to ensure a uniform developing.
The outside of the apparatus is finished in darkadmiralty grey synthetic enamel to give it a corrosion resistant finish.
A metaltemplate of 250 mm diameter have a central hole for marking and cutting thetest specimens, a specimen pressing disc, one hundred sheets of ammonia processpaper, and one bottle of ammonium hydroxide are supplied as standardaccessories.