SENSITIVENESS OF PAPER.
Bromide paper is usually made in two speeds, s'ow and rapid. The latter is number of different papers, which give almost any desired contrast.
111:Tnon OF EXPOSURE.
In taking up a fresh negative, a test should be made either with a strip of paper or in sections as described. The results of these tests are compared, and if necessary, further ones made until success ful. The exposure is then written on a thin strip of paper gummed to the edge of the negative for the purpose, giving par ticulars as to time, distance, and paper, assuming the light to remain constant. Thus a negative requiring six seconds at 18 in. on rapid paper is marked G-18-R. Of course, these tests must be developed as taken, but once the exposure is settled, the papers may go into a box and wait chiefly used for enlarging, and the former for contact printing. Both may be used for either process with advantage, as the rapidity of the paper greatly influences the character of the result. For example, the blacks of the rapid paper never reach such a deep tint as they do with the slow paper, and therefore the results are softer. So that, when printing from a hard nega tive, it is preferable to use rapid paper ; and when printing from a soft negative, or one inclined to flatness, the slow. A specially slow make of paper is supplied by some firms, for very hard effects. This, as already pointed out, is one of the advantages of the process ; as ranging from Carbon Velox to Kodak Rapid are to be developed together. With regard to
the number of prints, some workers mark each on the back as. clone, so as to avoid printing more than necessary ; but this practice is bad for the reason before stated. The best plan is to lay them all one way in the box and keep count ; those from the next negative being laid the reverse way, and so on. Or the required number of sheets may be counted out be fore commencing. Supposing the printer to be using the exposure box previously described, the back of frame is removed, and the paper placed in position. The lat ter should not be cut an exact size, but should be larger than required, to allow of trimming afterwards. The back is filled in, and the shutter drawn ; these operations only taking a few seconds. Dm ing the whole time, the paper may be left exposed in the room without fear. There is, however, one disadvantage in the use of this box. It sometimes happens that a negative is denser one side than the other, and needs to be shaded gradually across. When working on a board, this may easily be done by slanting the frame so that one side comes nearer the light ; but with a box any necessary dodging must be clone by covering up. Such nega tives, however, are not common, and be exposed differently from the general method.