Films. Among the substitutes offered for glass, negative. films, with or without a paper or other support, have met with the most favor
Both solutions are to be kept in well - stoppered bottles. A will keep good faff two or three weeks; It for several months.
For use, one mixes 100parts of A with 20 parts of B, and as this mixed developer will keep for a day in a well-stoppered bottle, sufficient for a whole batch of plates may be mixed at once. In this developer the image should appear in ten to fifteen seconds if the exposure has been correct, and the development should be completed in four to six minutes.
If overexposure is feared, the developer is diluted with half its bulk of water, or a com-mencement should be made with some of the developer which has been used for previous plates.
If, on the other hand, it is desired to force the development, there are added to each 100 cubic centimeters of the developer 2 to 5 drops of the following solution (C):
Strong Ammonia Solution..................
50 cub. cents.
The developer may also be made more active by increasing the proportion of B. - Dr. J. Eder.
7b Remove Hypo from Films. - In the Moniteur, M. Felisch recommends that in order to render harmless any traces of hypo that may remain in a plate after washing, it should be laid in an iodine bath, consisting of equal parts of iodine and iodide of potassium, dissolved in as much water as will make the solution the color of port wine. When removed from the solution the plate must be well washed again. To the foregoing the editors of the Mittheilungen add that they have often recommended the use of such a dilute solution of iodide - say 1: 100 - but remark that the plate should not be left too long in the iodine bath, otherwise part of the silver will be converted into iodide of silver, and for that reason they willingly use the iodine solution as a reducing medium in preference to cyanide of potassium.
I may here relate a little incident which occurred a few days ago in a studio of a first-class photographer. Watching him developing a plate, soon after the solution was poured on a slight scum came on the developer. "Adirty dish," I remarked.
" Impossible," was the reply, "you saw me rinse it well under the tap.
"Very well," I said, "before developing the next plate try rubbing your dish with a stiff brush and a little dilute nitric acid, and wash well with water and you will not be troubled with scum on your plates."
He took my advice, and having since followed it, that trouble disappeared. Rinsing a dish with water is very little good without a little elbow - grease as well. - William England.
872. Development is carried on exactly as for the dry plate. The same dishes, the developing solutions, are familiar to every one. Either the pyro with sulphite and carbonate of soda, as described further on, or the usual oxalate of potash and iron, may be used with uniform success.
Fixing is accomplished with hypo, as usual, and washing, just as you would silver prints and the most success. These films are supplied both in sheets or in continuous rolls, the former being backed while in the camera by a " carrier," and the latter, wound on spools, are carried across the camera-front by means of a very ingenious roll-holder. Films are also supplied upon that is, several at once. This also applies to fixing and development, as no injury to the film results from their passing over each other during any of the operations, if ordinary care is used to prevent bubbles of air remaining between the sheets.
In short, the operations may be described in their order, thus:
Exposure - Either with the roll-holder or the film-carriers, which may be purchased of any dealer.
Time may be determined by the usual tests; as a rule, less than is generally given a plate will suffice.
Development. - After your sheets have been carefully cut off at the regular distances, marked by the punch in the roll-holder, or on removal from the carriers, they are laid carefully in a dish of clean water of sufficient size to accommodate the number to be treated; care must be taken to avoid the formation of air-bubbles on the film while in the water; it is well to pass a camel's-hair brush, or the hand (if clean and soft), gently over the surface, to remove any that may appear. The object of placing them in water is to saturate the paper, and thus admit of its lying flat in the developing tray.
The formula for development comes with each package, and should be made as directed, so far as composition is concerned. Of course, there can be no such thing as a cast-iron rule for development, which requires modification with subjects that vary in character and timing, but the following may be relied upon to work well in the majority of cases:
Solution No. 1, as described in formula..................
Solution No. 2, as described in formula..................
Water, as described in formula ..................
The addition of about half an ounce of old developer to the above gives clearness and brilliancy to the shadows; it seems to have a ripening effect.
Now lay a negative - sheet in the developing tray, and let on about two ounces of water from the tap; this floats the sheets and prevents the paper sticking to the bottom of the dish, which would occasion uneven development, as this goes on from both sides. Now pour in your developer, and rock the dish sufficiently to cause a uniform mixture of the water and solution. Development will commence in about ten seconds, perhaps sooner. This varies with temperature and character of picture. If overexposure is indicated use the bromide solution as published in formula. If underexposed, increase the proportion of soda. Use judgment above all things, and you will be rewarded with success. The intensity is judged by looking through,as with a negative on glass, and should appear a trifle stronger than in the latter case. The rest of your sheets may be placed successively into the developer, and as many treated at once as you feel confident you can handle successfully. As each in turn indicates full development, transfer to a separate dish, for washing, which should take about a minute. Next place in a solution of alum as directed, for, say, half a minute, and then transfer immediately to the hypo solution. The strength of these two solutions is not important, provided you have neither too weak.