PRINTING FRAME.—A frame in which the sensitive surface of the paper is pressed into close contact with the face of the negative while it is being exposed to the light.
The ordinary printing frame consists of a wooden box-shaped frame, having a hinged lid to allow of the examination of the picture during the printing process. (See Fig. 358.) In choosing a frame the points to be observed are—First, that it is carefully made and perfectly square and true, otherwise the nega tive is liable to get broken when the pressure is put on. Secondly, the back should be hinged perfectly level, the joint allowing of no light to pass through. Lastly, it should be so arranged that there is no fear of the print or the negative shifting during any of the operations.
Durnford's frame is a very light and handy con trivance; it consists of a hinged backboard only, the negative being kept in position by springs.
In printing out upon glass or opals a specially constructed frame is required. A clever contrivance is that devised by Cowan. It is a frame made specially for printing out opals which are required to be ex amined during the progress of printing without fear of movement. It is also provided with a simple means of adjustment to allow for the various thicknesses of opal plates and negatives without fear of breakage. For the
printing of transparencies, provision is made for the inspection of same during printing through the opal. The frames are supplied with opaque masks, square and oval, to which the negatives are attached, and these are held in position in the frame by means of a hinged bar of wood and brass spring. The mask also serves to prevent the deep printing of the margins of the negative, which take up so much gold in toning. To attach the negative to the mask use a daub of the wax compound at the corners, and then lay on it the opal plate; and on its four corners at back also daub the wax. The hinged back is then shut down, and the com position causes the opal to adhere to the back of the frame; thus it can be lifted to allow of examination during printing.
For printing lantern slides from large negatives by contact, a frame constructed by Messrs. Adams & Co. is pro bably the simplest and handiest form. Fig 359 will show the plan adopted, whereby any part of the negative can be printed from, and not only any part but any angle. Two other ad vantages are, no risk of breaking the negative, and by means of wedges many slides may be made exactly the same as each other.