Now lift up the whirler from the bench, grasping the handle of the brace firmly in the right hand. Hold it at arm’s length, and by a series of quick jerks set the plate revolving. This will require a little patience to do evenly and rapidly, but with practice it will become quite easy.
The plate is coated twice, whirling it after each application of the sensitive mixture. The whirler is then laid upon the bench, and the hinge piece let down. This relaxes the strain upon the leather laces, and allows the jaw to be lifted and the plate removed.
An inverted revolving egg-beater may be made to serve for the same purpose.
DRYING THE COATED ZINC.
The film of albumen now requires drying, which should be done over a spirit lamp. The best form of lamp is one of the small pocket spirit stoves sold by ironmongers, and having the three supports for a kettle cut away. The zinc is held over the flame and kept in constant motion, so as to dry the film as quickly and evenly as possible; no fear need be felt at applying too great a heat so long as the metal can be held comfortably in the fingers. When dry, the plate is ready for printing upon.
For drying large plates, two or more of these stoves would be required, but it is very easy to extemporize a suitable arrangement, by laying a large pad of cotton saturated with spirits of wine in a tin dish, and setting it on fire; by this means a stove of any desired dimensions can be prepared quickly. To extinguish such a flame, cover it with a large sheet of zinc.
It must be borne in mind that the film on the zinc is now very sensitive to {43} light, therefore the preparation of the film must be done in a yellow light, as must also the operation of placing it in the printing-frame, inking up, and development; gas or lamp light may be used, as the film is not sensitive to artificial light of a low actinic power.
THE PRINTING FRAME.
The printing-frames used for this purpose must be of the box pattern, fitted with stout plate-glass fronts, the cross bars behind being fitted with wooden screws, instead of springs, as absolute contact can only be obtained between the surfaces of the glass negative and zinc plate by means of screw-pressure.
The front glass of the printing-frame must be kept perfectly clean, and especial care must be taken that no grit be upon either glass, inside the frame, or on the back of the negative, else the negative will be broken.