The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Silhouettes, Photographic                        Silk, Printing on
Holetschek's Table of Drop-shutter Speeds.
To use this Table find the distance of the opening of the dropping piece of the shutter above the lens, measuring from centre to centre of each. Example: - Assume this to be 8 cm., the lens has a diameter of 20 cm., the time of exposure is -£% sec.
Silhouettes, Photographic. The sitter is placed against a thin screen strongly illuminated from behind; an excellent plan being to stretch the screen over the doorway of a passage in which the camera is placed.
Silk, Printing on. Many photographic processes are ap-plicable to silk and other textiles; for example, the direct Cyanotype process (see Cyanotype), and practically all silver processes which do not involve the use of a definite colloid coating or film, although a trace of gelatine as a sizing agent is often useful. The following is applicable to silk, muslin, linen, or canvas : -
Water...... ......... 10 ozs.
Common salt         ... ......... 100 grs.
Gelatine ... ......... ... 20 ..
Dissolve with heat and uniformly moisten the textile, which may be conveniently stretched on a frame. When dry, moisten with a solution of silver nitrate, 40 grains to the ounce. The material being once more dry is ready for printing. Toning and fixing as for prints on Albumenised paper (see Albumenised Paper). For making enlargements on canvas see Enlarging, and for dyeing processes on textiles see Diazotype and Dyeing.