The water has probably made the section quite limp, and it should be immersed quickly by sliding it into the solution face upwards. This allows the developer to flow across it evenly, and as soon as this has happened you should turn the film over so that the sensitive side is next to the bottom of the dish. The film will then probably arch slightly in the middle, but after a few seconds it will flatten out, and there is no need to touch it again for a few minutes. The progress of development can be watched from the back of the film, and the amount of density that it has attained can be judged to a nicety.
Another convenient method of developing the separate exposures which may be preferred is to fill a flat-bottomed measure, or, better still, a thin tumbler, with developer, and put the sections into that. The slight curling makes the film go conveniently into the glass, and the progress of development can be watched through the sides of the tumbler. Air bubbles, if they form on the gelatine surface, can be shaken off instantly by pressing the palm of the hand over the top of the glass, and shaking the glass and contents once or twice with the other hand, or the film may be lifted up and dropped back again two or three times.
There are one or two useful commercial appliances for keeping film sections flat, and in this connection I might mention the " Primus " film-holder, which consists of two small clips, which grip the edge of the film, and are themselves held in place by a spring handle. This little piece of apparatus entirely removes the necessity of dabbling one's fingers in the developing solution, and in the case of pyro this is an advantage not to be overlooked.
This method of tentative or personal development has many adherents, and I have therefore devoted more space to it than I perhaps should have done otherwise. Roll film users have, however, discovered that there are other and easier ways of obtaining negatives, and the majority of them have adopted the strip method. This, as the name implies, means developing the whole spool at once. The black paper is all unwound, and the sensitive film is rolled up in the hand before development. A pair of strong clips, sold by most photographic dealers, should be first attached to the two ends of the strip. The preliminary washing is carried out by drawing the film through a bowl of clean water, and development is conducted in much the same fashion. Big dishes are necessary and plenty of developer; but for expedition there is nothing like it, although, in the case of a very varied series of exposures, one may now and then find one negative that requires longer development than the others. If such a case occurs, that negative must be cut out and allowed to remain in the developing bath after the others are done, but the occurrence is rarer than one might be led to suppose.
As far as my own practice is concerned, I have almost entirely adopted Mr. Watkins's method of development by factor, and find it by far the most satisfactory way of obtaining good and regular results. In the chapter of this book devoted to Negative-making the factorial method is fully described, so that I scarcely need occupy space with it here ; still, there are just a few points to be remembered. A slow developer, with a high multiplying factor, is not particularly suitable for the ordinary strip development, as the continual and necessary movement of the arms is liable to tire one before development is really complete. Rodinal, which, in my opinion, is the simplest and best commercial developing agent obtainable, had practically to be discarded on this account. Negatives developed with rodinal lose some of their density in the fixing bath, and the time of development is rather long to compensate for this. I therefore used for some time the following pyro-soda formula, which gives negatives of a particularly useful character. As will be seen, however, it differs but little from the Barnet pyro-soda developer given in the chapter on Negative-making.
Carbonate of soda .... 3 ounces Carbonate of potash 1 ounce.
For normal exposures use equal parts of No. 1 and No. 2, together with sufficient water to double the quantity used of the two solutions. As this is somewhat apt to oxydise rapidly, a little metabisulphite of potash should be added. The factor for this formula is ten, and development is usually complete in six or seven minutes.
As, however, I have a great liking for the delicate negatives that rodinal alone seems capable of yielding, and at the same time was sufficiently enamoured of the " always ready " character of that estimable preparation, I devised a means of overcoming the tiring way of " sawing" the film up and down during the twelve long minutes that rodinal demands : and this is what I did. A screw eye was fixed into the wooden ceiling of my dark room, and a thin cord with a small weight attached was passed through it. To the other end of the cord a strong clip was fastened, and this clip received one end of the film. I then got one of the special film developing dishes (of which there are several patterns obtainable) mounted on a wooden base with an adjustable arm for passing the film under. This arm carries a vulcanite roller, and by means of this the film is kept beneath the surface of the solution; the weight attached to the cord keeps everything taut, and then all one has to do is to pull the clip attached to the othet end to and fro, and the whole film is developed with an ease and convenience that must be tried to be believed. A similar device was recently described and illustrated in the " Photogram".
Sulphite of soda .... 6 ounces.
Pyrogallic acid.....I ounce.
Barnet Roll Films Are Orthochromatic And Non-Curling. Made To Fit All Daylight-Loading Cameras. Can Be Confidently Recommended. Perfectly Coated With An Extremely Rapid Emulsion. Very Rich In Silver, Giving Very Great Latitude In Exposure.