Etching having been completed, the plate is cut off about in. beyond the edges of the sub ject, and this margin given a bevelled rebate to allow of nailing to the wood mount.
916. As regards ease of working and quality of the half-tone reproduction, photographic originals may be arranged in the following (decreasing) order of preference Black-tone prints on glossy or semi-glossy develop ment papers (white).
Carbon and Carbro prints of black tone on white smooth support.
P.O. P. prints of warm black tone.
Wartn-tone or sepia-toned prints on glossy or semi glossy development papers (white).
Prints on smooth matt white papers.
Red-toned prints, red carbon prints, and prints on tinted papers.
Rough-surface and textured prints.
A kind of original which should on no account be sent to the photo-engraver, if any other is available, is a positive transparency. The en graver will usually make a copy negative from it, and from that a print, with the result that the half-tone block is almost always greatly inferior to one made from a print from the original negative. It must be borne in mind that there is a reduction of contrast and some loss of fine detail in a half-tone reproduction. A satisfactory result must not be expected except from a perfect original ; if the latter is poor, it is well to have it worked up by an experienced retoucher of originals for process reproduction.
Fine etchers are not necessarily artists, and often attempt to improve the reproductions of originals which they consider poor in one way or another. Hence, when it is a question of reproducing a photograph in which the contrast or tones represents a definite artistic aim, it is well to insist that the reproduction shall be as nearly facsimile as possible. The schedule of charges for ordinary work, even on copper, scarcely allows of the care necessary for the finest results, and it is better to pay more for a superior grade of quality.
Originals sent to the photo-engraver should be lightly marked on the back with soft pencil only. They should be carefully packed between stout cardboards or inserted in a cardboard tube for protection against creasing or damage in transit.
917. In addition to the size of the repro duction, already referred to in § 928, originals require to be marked with particulars of the screen and edging of picture which are desired. These particulars should be marked on the margin of a mounted print or on a strip of white paper attached to the back of the original with a touch or two of gum.
The following table shows the rulings of screen to be used for half-tone blocks suitable for various descriptions of printing. The screens commonly kept by most photo-engravers are indicated by heavier type— Lines per inch Description of printing 50, 55, 6o Daily newspapers printed on rotary machines 85, oo Newspapers, etc., printed on fiat-bed machines.
120, 133 Average work on medium-quality paper. 150, th5 High-class printing on art paper.
75, 200 Superfine printing of the highest class_ In case of doubt as to the screen to be used it is well to confer with the manager of the printing works.
The picture on a half-tone block may be made rectangular, circular, or any other shape ; it may also be vignetted to an irregular and shaded. outline, or s' routed to outline," i.e. the back ground cut away round the subject.
As regards a surround for the subject, this may be a thin black rule or line (which is fre (iuently of assistance to the printer) close against the picture ; or this rule may be at a slight separation produced by the cutting of an inter mediate white band about in. in width with a graving tool. This latter finish is usually given unless " solid rule " is ordered.
The part of the subject to be included may be shown by pencil lines on the face of the original, or by marks indicating the ends of the diagonals of a rectangular picture or axes of an oval ; or, again, by a paper mask attached to the back of the original so that it can be folded over on to the front.
Also, as required, the original should be marked to indicate the outline of a vignette or the line to which the bust in a portrait is to be cut away.