THE PHOTOGRAPHIC NEWS. Vol. 1, December 10, 1858

THE COLLODIO-ALBUMEN PROCESS.

5th stage--Exposure.--AS most operators agree that the development should not be delayed beyond two or three weeks of course it matters not in what part of this period the exposure takes place. The time in this process need not be measured so exactly as with any other kind of sensitive plate or sheet, but an approximate idea only can be given.. In summer, with sunshine, a stereoscopic landscape, lens with ¼ inch opening, will average 1½ or 2 minutes. With a 16 inch focus lens, and ½ inch opening, from 5 to 7 minutes will be requisite; but in a deep wood I have had to expose 30 and 35 minutes, and even wet collodion would have taken 10, though the sun was shining brilliantly--so that the operator must judge for himself. If there are dark nooks and patches in his picture, he must expose for them, as he can remedy over exposure. In the next stage, which is 6^th--The development, my method differs from the general one. I use

Pour water over the plate, then drain and level the plate, which is well done with a funnel placed in a round hole, cut in an old box, or board supported at each end. Pour upon it the gallic acid and silver solution; see that it covers the whole plate, and then it may be left ten minutes or there-abouts, when it must again be looked at, and if the details are not coming out pour off and add 1 part gallic acid solution, and one part silver. This will generally give the blacks greater intensity, and in time, betwixt 30 minutes and one hour, the negative should be fully out; but sometimes it takes much longer through under-exposure. A few days ago, I took some views on a peculiarly dark day, which were three hours in developing, although in the last hour I used an equal mixture of the silver and gallic acid solutions. Yet the whites are as transparent as though they had been exposed in summer, and developed in half an hour. The time taken by development seems long, and would be so for twenty pictures, but it is easy to develop three, four, or even a dozen at once. I always bring out a quantity at the same time, so that this quantity only takes the real time that one or two would if brought out singly. A good picture in this, as in every process, should have dense sky and the minute markings in the shade.

I before observed that this mode of developing differed from that in general use. My own, and many of my friends' opinion, is, that the above is the safest, and gives the best half tones. I have, however, known many operators who prefer the one more generally used; so I will give that as well, that the beginner may try both, and make his own choice--

In a dish of this solution place the plate, and in a few minutes add a drop or two (not more) of a 40 grain solution of nitrate of silver to an ounce of water, and the development will be complete in an hour or two. If the blacks are not intense enough, or if the development seems to become stationary, add a few drops of the silver solution.

The measure, which is used for the gallic acid and silver should be perfectly clean; indeed, it is the safest way of proceeding to wash the measure, after developing, with a strong solution of cyanide of potassium, and after that, well with water. Nothing remains now but the

7th--Fixing and varnishing.--It was the custom with many to use cyanide of potassium to fix the collodio-albumen negatives, but this I have proved to be a great mistake by fixing one by this salt, and another by hyposulphite of soda, and comparing them. In the first place, the time it would take to dissolve the iodide of silver out of the "whites" by cyanide, is long enough for the opacity of the "blacks" to be much--very. much--injured. Again, very often it curls up the film, so that in drying, marks are left like cracks in the glass, and frequently it loosens the coating so that it leaves the glass. Hyposulphite of soda is free from all these faults, and if the plate is placed in a solution of 1 oz. of the latter to 6 oz. of water, from 10 to 20 minutes will suffice to fix it, which can readily be seen by the yellow colour leaving the unaffected parts transparent and clear. Wash gently, and leave the plate in water for an hour, renewing the water once or twice. Wash then, and dry by gentle heat, when it must be varnished. Each maker has the way to use his varnish marked upon his bottles--whether with heat or no. That which I use requires no heat, and is very good; but many prefer that which is applied whilst the plate is Warm. But if the cold plate is used, it must be perfectly dry.

Causes of failure.--This I always look upon as a necessary chapter in the description of any process, as few photographers are chemists, and still fewer have any teacher to appeal to in case of failure. The greatest reputed drawback to this process is blistering of the plates. I never had but one blister out of hundreds of pictures; but my friends occasionally have had some great disappointments from this cause, and in every instance which I could thoroughly investigate I have, proved that the plates were not dried properly after albumenising the collodion filth, and almost always that they were stowed away damp after the last bath. This does not show until in developing small blisters rise like bubbles, and in drying leave a mark which is printed. I once, for a friend, developed a lot of scenes in the wildest part of Scotland, and none but an artist could imagine my vexation at seeing the most exquisite scenes I ever beheld, without any exception, Come out, and then be spoiled by blisters like bubbles rising as thickly as rain-drops, and spoiling every plate.

My belief is, that if a man will use proper collodion, and attend to this particular, he need not meet with this failure. Neither thick nor thin collodion is the cause--that I proved, and stated my experiments in one of the journals; and I have come to the conclusion that it is either an unsuitable collodion or the want of dryness in the plates.

It will be understood that dust, which causes spots On the picture, must be guarded against.

Some of the advantages of this process seem to me to be--the keeping of the plates, which I have stated. to be on an average three weeks. I have, however, last week been using a lot of plates prepared in August, and kept since then in a tin box: the results are as clear in the lights as if they were not a week old--the blacks are intense, and the minuteness and half-tone almost, if not quite, as perfect as I ever got. Surely this says enough for their keeping qualities.

Again, I am using the same silver bath which I have used two years; of course, having replenished it often with a 40 or 50 grain solution of silver. When it becomes deeply discoloured, as it does at times, I add a little kaolin, shake up, leave for a few hours in the light (I find the light aids it in clearing), then filter into the bath again. If the negative looks very dirty, When dry rub it gently with a soft silk handkerchief, and this will often remove this appearance, as it frequently arises, from a deposit. which takes place in developing; but this is very seldom the case if the things are clean.

The stages of this process seem many and intricate, but as this account is written for the younger student, it must be remembered that I have made them separate so as not to be overlooked; and I believe that some of them may be performed in a very little longer time than described.

My own belief is, that the first preparation, up to the time when the plates are dry, may be performed by daylight; but let not the beginner try any experiments. The reason why I give this opinion is, that I was once preparing a lot of plates, when a friend of mine threw open the door, and the sunshine fell upon three or four before the albumen had been applied. These I marked as experimental, but in bringing out the pictures I could perceive no difference whatever betwixt these and others prepared in the usual manner.

As to the results of the above process, I must refer the reader to the editor of this journal; as he, having seen a few, is a less interested person than myself.

[We can assure our readers that the pictures which our valued correspondent has from time to time forwarded to us as specimens of the collodio-albumen process, which he has so intelligibly described, leave nothing to be desired. We can confidently recommend the above paper to the careful attention of our readers--ED.]