We roughly centre our light, but when we look at the focussing screen in the position where our lantern plate will be, it is probably quite unevenly illuminated, and we may be puzzled how to adjust our light and see our focussing screen at the same time. Before bothering about even illumination, place the negative in position and adjust the camera to get the exact amount of reduction required. Perhaps with the negative in focus we may not realize our illumination is defective, but after getting the image into approximate focus and size, remove the negative and see if the light on the focussing screen is even. Should it not be so, set a mirror at such a position that the reflected focussing screen may be seen when manipulating the light, which may require to be nearer to, or further from, the condenser ; or raised or lowered. When the light is in correct position replace the negative and make the exposure. The light may be sufficiently, cut off while withdrawing the shutter of the slide by interposing a piece of cardboard between the light and the condenser.
Supposing our slide made and dried, and we find that it answers the requirements laid down for the perfect slide, we proceed to its finishing. Should it not be up to standard, remove the film by placing the plate in a weak solution of hydrofluoric acid, and after rinsing and drying, it will serve as a cover glass. Nothing shows the good taste of the worker more than masking, and the greatest care should be taken to do this properly. Commercial masks are sold in a large variety of shapes, and it is well to obtain a variety of oblong ones with square corners properly cut.
MASKING THE SLIDE.
Now and again an oval or round may be necessary, but eschew the rounded or cushion corners, which were no doubt brought out because the makers found a difficulty in cutting good squares. Even when a, slide is made by contact it will be frequently improved by using an oblong rectangular mask instead of the full square. Many workers prefer to cut their own masks, and for this purpose boxes of square black paper are supplied with white lines ruled in both directions for accurate cutting. If using these masks they should be placed on a sheet of flat zinc and cut by means of a sharp and pointed knife drawn along a steel straight-edge. Boxes of black gummed strips are also sold of various widths and 3 1/4 inches long which may be converted into masks by sticking them down parallel to the side of the slides. The slide being masked it may be titled by writing in white ink on the mask - we do not like titles printed on the slide itself - and then two circular white spots should be placed at the top corners either with white ink, or by means of the small gummed spots sold for the purpose. These spots are essential, for every lantern worker then knows how to place the slide in the lantern. Some workers prefer what are known as " duplex " masks, which are white on one side and black on the other. These are placed on the slide with the black side below and the titles are written with black or coloured ink, and the spots at the top of the slide must also be made in the same dark colour.
This has always been the bugbear of lantern slide making for the amateur, and all sorts of things have been brought out to simplify, the process. The slide being masked, it is examined and if there are any little transparent holes they are carefully spotted-out with a sable spotting brush and a little water-colour. All dust is removed and a clean cover glass is placed on it to preserve the film, and the whole is bound together with a paper binding. Some workers prefer to use prepared glass plates with binding strips attached, and these are simple to use, but we should suggest that when they are placed in position, the flaps of paper which fold over on to the slide itself, instead of being moistened only, should be pasted with Johnson's Mountant and then, when they are quite flexible, pressed down into position. Other workers prefer to use an ordinary cover glass and the long strips, and when purchasing strips they should be procured with a special cement surface rather than ordinary gum. Such strips are moistened with hot water, placed at full length on the
BINDING THE SLIDE.
table and allowed to remain for a minute until they become limp; the slide and cover glass are then taken between the finger and thumb, placed at one end of the strips so that there is an equal overlap on each side and then wound over from corner to corner, at the same time pressing down the paper on to the slide, but missing the corners. When the last side has received its binding the end is clipped off with a pair of scissors and a cut at each corner will remove a V-shaped piece, thus allowing the paper to fold nicely into position. If the slide is now placed flat on the table and gently pressed, the binders will be likely to nicely adhere, and when it is dry any surplus gum may be cleaned from the two glass surfaces. Perhaps the most useful adjunct for the purpose of binding is the " Specialist Lantern Slide Binder." This consists of two brass rollers covered with rubber ; and the slide with cover glass in position, having been placed on a length of moistened binding strip is pressed between the two rollers, as shown in the illustration. It is advisable to keep a moist sponge handy to wipe surplus gum or paste from the rollers from time to time. Although the short length strips may be preferred with this binder, some of our professional friends find no difficulty with the long ones.