The Dictionary Of Photography

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

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Opalotype
To make the emulsion
Take of No. 2          ............ i5omins.
No. 3          ............ 150 ..
.. No. 4          ............ 28 dfrns.
Mix, and add gradually, with constant agitation,
No. 1.................. 75 mins.
Give the plates an edging of albumen or india-rubber solution a quarter of an inch broad, and, after coating, allow them to dry thoroughly. The prints should be washed, toned, and fixed in the same way as ordinary silver prints, or the sulpho-cyanide toning bath may be used with better effect. (See Toning.) As it is necessary to examine the opal during the operation of printing, it is obvious that some arrangement must be made for replacing it in exactly the same position. Printing frames may be obtained commercially specially adapted for this work, but an ordinary printing frame may be utilised in the following manner : - Replace the hinged back by a solid piece of wood TV of an inch less in thickness; coat the inside of this back with a composition of gelatine made as follows : -
Gelatine (Nelson's X opaque) ...... 1 oz.
Water           ... ... ... ... ... 4 ozs.
Glycerine ... ... ... ....... 2 ,,
Soak the gelatine in water, and dissolve by the aid of heat; add the glycerine last. The opals will adhere to this on being damped, or a thick india-rubber solution, with a little castor oil added, may be used : -
Pure masticated rubber ... ... ... 40 grs.
Castor oil ...... ... ... ... 10 drops.
Benzole         ... ... ... ... ... 1 oz.
A small Spot of this at each corner will cause the opal to adhere firmly to the wood. To keep the negative in position, a screw may be driven through one end of the printing frame, and the point of the screw cut off; a groove cut in it in which to fit the negative. To the back affix three or four small tongues of metal pierced with holes, which holes may drop over pins driven into the sides of frame, or the back may be permanently fixed by a hinge to one end of the frame.
475