Part 2
The process of obtaining a picture on Dry Collodion plates is in itself a most simple and easy matter, but there are one or two precautions that appear necessary to ensure success that cannot be lightly neglected. In the first place, it is absolutely certain, that if we want a clean and bright picture, we must have a plate perfectly free from all extraneous matters, such as soap, grease, &c. Various plans for cleaning the glass plate have been proposed, all more or less successful, but in most of them there is one great fault, namely, that of using a powder, as tripoli, rotten-stone, &c. to rub off the dirt with. Now we find that in practice this will not answer, from the almost impossibility of getting rid of the floating particles of the powder when the plate is rendered slightly electrical by rubbing, and as each of these particles if it become enveloped in the Collodion film, would produce a spot on the finished picture, we find it necessary to search in another direction for a detergent for the glass plate to which this objection would not apply. One soon presents itself in the form of _old waste Collodion_--this spread on the glass plate and rubbed off again with cotton wool, makes the best and most perfect cleanser hitherto proposed, without any of the objections usually appended to other materials used for the same purpose.
The next precaution necessary to be observed is, that all the solutions should be perfectly bright and clear; they should be absolutely free from floating particles of any kind. This is essential, as it is impossible to obtain clean pictures without attention to it; the floating bodies in the solution settle on the plate, and form so many nuclei, around which, in the development of the picture, the silver is deposited in an opaque mass, forming spots and blemishes on the surface of the plate.
There is one precaution that cannot be dispensed with, and that is, to be sure that the chemicals employed are of absolute purity; without this, success is very problematical, and vexation and disgust the sure reward of its neglect.
The process may for convenience be divided into the following stages:--
1.--Cleaning the plate. 2.--Coating it with Collodion. 3.--Rendering the plate sensitive. 4.--Applying the Preservative solution. 5.--Exposure in the camera. 6.--Development of the picture. 7.--Fixing the developed image. 8.--Varnishing the finished negative.
CLEANING THE PLATE.
The glass plate is first to be thoroughly washed with an abundance of water, and dried on clean cloths; it is then to be placed in the plate holder (_Fig. 1_), and have poured over its upper side a small quantity of old Collodion. Now take a tuft of cotton wool and rub the Collodion all over the plate, giving the hand a circular motion at the time: keep rubbing until the Collodion is very nearly dry, then turn the plate in the holder and repeat the same treatment with the opposite side; then lean the plate thus treated against a wall, while another, or any number are put through this stage. When a sufficient number have been so far cleaned, the plate holder is to be carefully wiped, and the first plate--the edges of which have also been carefully wiped with a _clean_ cloth--is to be replaced, and treated with a smart rubbing with a wash leather, the operator at intervals gently breathing on the plate. Both sides of the plate being cleaned in this way, it may be removed, after again wiping the edges carefully, to the plate box, to await the subsequent steps of the process. Plates cleaned in this manner should look perfectly transparent, and free from any marks of the cloth or leather, and when breathed upon should condense the moisture of the breath in one uniform degree over the whole surface. If patches of uneven condensation appear, a repetition of the process must be had recourse to.
The plate being clean, we proceed to the next step,
COATING THE PLATE.
Lay a piece of clean blotting paper on the table, larger than the plate we are about to use; place the clean plate on this, and then bring the pneumatic plate holder to bear on the centre of the glass, making sure that it has laid hold firmly. We then raise the plate with the left hand, and bring the surface upwards which was previously on the blotting paper; it will no doubt be found that small particles of dust have attached themselves to the plate, these must be removed by a broad and soft camel's hair brush, kept for this purpose only.
The Collodion is then to be poured on, as shown in the diagram (_Fig. 2_), and the superfluous quantity returned to the bottle from one of the corners of the plate. It does not matter which of the corners is used for this purpose, that which is most convenient to the operator assuming the preference. If the Collodion should have a tendency to set in ridges across the plate, a rocking motion, while the delivery corner is in the mouth of the bottle, may be given to it, still keeping the plate in a vertical plane. This will restore the film to perfect evenness and freedom from irregularity of any sort. The plate should be held in the vertical position for a few moments before being placed on the dipper to undergo the next operation of
RENDERING THE PLATE SENSITIVE.
The plate being placed, coated side outwards, on the dipper, is to be plunged without hesitation into the nitrate of silver bath (_Fig. 3_). This must be done without stopping, otherwise a line across the plate will indicate, on development, the position of the plate in the bath at the time this stoppage took place; so that if we were to immerse the plate by a series of jerks, we should have as a result, so many bands of unequal development in the finished picture; showing the importance of plunging the plate into the bath without any stoppage during its descent.
When the plate has rested for half a minute in the bath, it may be withdrawn, and quickly re-immersed. This washing must be continued at intervals, until the greasy appearance goes off, generally for the space of two minutes, when the plate is to be taken out of the bath and placed with its lower edge on a pad of blotting paper, in a position as shown in the cut (_Fig. 4._) A fragment of blotting paper is then to be used to absorb the moisture from the back of the plate, and a pneumatic plate holder--which should only be used for this purpose--is applied to it to form a support while
APPLYING THE PRESERVATIVE SOLUTION.
Taking the plate in the left hand by means of the pneumatic holder, incline it as shown in the diagram (_Fig. 5_); then having poured into a perfectly clean measure rather more of the preservative solution than is necessary to cover the plate twice,[B] pour half of it along the upper edge (A B) in such a manner, that a wave of the solution may flow uniformly from one end of the plate to the other; allow this to flow off into the waste pan or sink, and then bring the plate to the horizontal position, and pour on the remainder of the preservative solution, eight times at least, allowing it to flow back into the measure from each corner in succession, in order that the whole plate may be brought uniformly under its influence. The plate is to be again placed on a piece of clean blotting paper (as shown at _Fig. 4_), and its back once more wiped with a fragment of blotting or papier Joseph, in order to remove any of the preservative solution that may have run from the surface to the underside in the previous operation. The plate thus preserved is to be reared on a piece of blotting paper with its face against the wall until dry, and is then to be stowed away in a plate box, perfectly light-tight to await the
[B] A plate, 9 inches by 7, takes about 1 ounce of solution.
EXPOSURE IN THE CAMERA.
Collodion plates preserved as above directed, will keep perfectly good and sensitive for 12 months at least; and from the appearance of the developed image on a plate that has been kept that time, I see at present no reason why, if preserved from the damp, they would not keep indefinitely. In my experiments, I have never found the least difference in sensitiveness, whether the plate be used within a few hours of the time of its preparation, or has been kept for months; until, however, we have had more experience in the matter, it would be safer not to rely on plates more than 12 months old.
The time of exposure in the camera, of course varies in this process, under the same circumstances as it does with the wet Collodion; but I have found as a general rule, that it is better to give the plate a full exposure than to fall into the opposite extreme: that is to say, it is preferable to expose the plate sufficient time for the deepest shadows to make an impression than to close the dark slide at an earlier period, the mode of development allowing considerable latitude in this particular. With a 3-inch single lens, 16-inch focus, with a ½-inch stop, the usual time for a bright landscape will be about 5 minutes; this of course is merely an approximation to the time of exposure, the exact time can only be arrived at by experience. I do not think I can do better than follow the plan adopted in my "Practical Photography," of giving instances of under and over exposure, as a means of educating the tyro in the appearances that result from these conditions of the plate.
If the exposure has been of too short duration, the image will come out under the developing solution with difficulty; and after a continued immersion in it will only present the high lights, the deep shadows not being represented, or, if so, in so faint a manner as to be useless in the picture.
An over exposed plate, when treated with the developing solution, will almost immediately give indications of the picture; and in a few minutes, the whole of the picture, _deep shadows and all_, will come put in unnatural force; on looking through the picture thus produced, we shall observe a great flatness in it, there is a want of contrast between the various parts, and although by continuing the development we might obtain a tolerably intense negative, the resulting picture would be flat, meagre, and unsatisfactory: on the contrary, a plate that has been exposed for the correct time, will comport itself very differently under development from the foregoing.
The sky and high lights will first appear, then the half tones, and lastly, the parts of the picture that were in deep shadow will show themselves; this effect should take place in about five minutes from the time of immersion in the developing bath: a picture that comes out sooner than this, is, as a general rule, over exposed; and one that is much after the five minutes before it makes its appearance, may be considered as under exposed.
We trust that the above instances may be of service in indicating the average time required for an exposure of the plate, but we must ask the reader not to take the figures given as actual values, but merely as very close approximations to the truth. We will imagine the plate to have been properly exposed, and proceed to
THE DEVELOPMENT OF THE PICTURE.
It is not necessary that the picture should be developed immediately after exposure in the camera; any time that is convenient to the operator may intervene between the processes, provided the aggregate time before and after exposure does not exceed the limits of keeping power of the plate.
The development of the picture may be conducted in two ways, either by immersing the plate in baths or dishes, or by placing it on the levelling stand and treating it with the solutions, in their proper order, as detailed below. Each plan possesses certain advantages, but it is of little consequence which one is followed. Perhaps there is less danger of the film washing off if the plate be treated on the levelling stand, and on the other side with large plates it is more difficult to cover them evenly with the developing solution than it is simply to immerse them in a pan of solution. We say to the reader, try both ways, and make your own selection.
The plate upon being removed from the camera is placed face upwards in a porcelain or glass dish of a convenient size (not too large), and sufficient distilled water is to be poured over it to cover the surface thoroughly--this is for the purpose of softening the preservative solution, and must be allowed to remain on the plate for five minutes; the plate is then to be lifted in and out of the water by means of the silver hook. This done, remove the plate to a perfectly clean dish, and pour carefully over it the developing solution, composed of
Saturated Solution of Gallic Acid (p. 10) 8 ounces. Solution of Nitrate of Silver (p. 10) 2 drams. THOROUGHLY MIXED.
In a few minutes the picture will begin to make its appearance, and will gradually unfold its details under the influence of the developer, until the whole of them are apparent; on raising the plate, however, when this stage of development is reached, and viewing it by transmitted light, the picture will appear weak and poor; we must now remove the plate from the bath, and add 2 drams more of the nitrate silver solution, and having thoroughly mixed it with the gallic acid already in the dish, we return the partially developed plate, which in the course of a few minutes will have acquired a great amount of intensity,--the exact degree can be regulated by the time of immersion: when the picture appears sufficiently intense, it is to be removed from the developing dish, and a gentle stream of water is poured over it, in order to remove any adhering developing solution, and stop all further reducing action on it.
During the whole time of the development, the gallic acid should remain quite clear; it will become slightly discoloured before the end of the development, but it ought not at any time to become muddy, or it will deposit a sort of sandy sediment on the surface of the plate, which cannot be removed by subsequent washing.
The usual time occupied in the development of a successful picture is from 20 to 30 minutes, it might be developed much quicker by using pyrogallic acid, but at present I give the preference to the developer I have described, as I believe it to be more certain, and more under the control of the operator than the pyrogallic acid; and further, as it is not necessary to watch the development all the time it is going on, there can be very little saving of time in the more rapid method of bringing out the latent picture.
The picture being washed free from the adhering developing solution, is to be placed on the levelling stand, and subjected to the seventh part of the process--
FIXING THE DEVELOPED IMAGE.
This is accomplished by pouring over the surface of the plate sufficient solution of hyposulphite of soda (p. 15) to thoroughly cover it, this will dissolve out the unaltered iodide of silver, and give us a clear and bright picture, in which the deep shadows should be as transparent as the glass itself, and the high lights as dense as a piece of metal, the intermediate tones assuming their proper positions according to the intensity of the light that was concerned in their formation.
When the whole of the yellow iodide of silver is removed, the fixing solution may be thrown off, and the plate must be treated with an abundance of water; too much cannot well be given at this stage, as the hyposulphite adheres with great tenacity to the plate, even after a good washing. The back of the plate must be washed as well as the front, for I have found that a neglect of this precaution has ruined many a fine negative; the hyposulphite remaining at the back finding its way by capillary attraction to the surface, and once there, its destructive qualities are sure, sooner or later, to render themselves evident.
The picture being thoroughly washed, and either dried spontaneously or by the fire, has only to be covered with a film of varnish. And now comes the last operation, of
VARNISHING THE FINISHED NEGATIVE.
Benzoin varnish is the best coating that can be given to a Collodion negative. It resists the action of pieces of grit; it does not crack; and, above all, it does not, like amber varnish, split off the picture on the slightest friction.
The application of this varnish is a very simple matter. The negative is to be again placed on a pneumatic plate holder, and the varnish is to be poured on to the surface in precisely the same manner as the Collodion was at the commencement of the process, the superfluous quantity being returned to the bottle: in a few moments the varnish will be quite dry and hard, and the plate may be handled with perfect safety.
I may mention, as a precaution, in varnishing the plate, that it is better to perform that operation in a still atmosphere; as the solvent of the gum being chloroform and very volatile, if it were conducted in a current of air, there might be some difficulty in obtaining an even coating to the picture.
In concluding this description of a process, which is at once simple and certain, I would ask the patient attention of those who may do me the honor of repeating my experiments. I have endeavoured to render the details of the process as intelligible as possible, and if I have succeeded in advancing the art of Photography only one step by so doing, I consider that it is an ample return for hours and days spent in anxious thought and laborious experiment.
FINIS.
SPECIAL LIST OF REQUISITES
FOR THE
=DRY COLLODION PROCESS,=
SUPPLIED BY
Messrs, BLAND & LONG,
Opticians, & Photographic Instrument Makers
TO THE QUEEN,
=153, FLEET STREET, LONDON.=
* * * * *
BLAND & LONG'S
=IODIZED DRY COLLODION.=
This preparation will keep for an indefinite period, and can be exported to any climate, without risk of deterioration.
_Half-pints, 10s.; Pints, 18s._
* * * * *
BLAND & LONG'S
=PRESERVATIVE SOLUTION,=
READY FOR USE.--_1s. per pint._
BLAND & LONG'S
=BENZOIN VARNISH,=
FOR PROTECTING THE FINISHED NEGATIVE.
_1s. per oz._
This varnish does not require the plate to be warmed; but dries instantly, leaving a perfectly hard transparent coating on the picture.
* * * * *
=NITRATE OF SILVER BATH,=
FOR BLAND & LONG'S DRY COLLODION,
Ready for immediate use.--_7s. 6d. per pint._
* * * * *
=PURE CHEMICALS.=
_s._ _d._
Fused Nitrate of Silver, absolutely pure 4 6 per oz. Glacial Acetic Acid 1 0 " Pure Gelatine 0 6 " Pure Citric Acid 0 6 " Gallic Acid, pure 1 6 " Iodide of Cadmium 3 0 " Hyposulphite of Soda 1 0 per lb. Pure Sulphuric Æther 0 6 per oz. Absolute Alcohol 0 6 "
* * * * *
FOR THE PRICES OF APPARATUS
SEE
=BLAND & LONG'S=
Illustrated Catalogue of Photographic Apparatus
_Sent free by post, on application._
SENSITIVE
=DRY COLLODION PLATES,=
READY FOR EXPOSURE IN THE CAMERA.
(=LONG'S PROCESS.=)
* * * * *
Messrs. Bland & Long are now prepared to supply these plates, carefully secured in sealed cases, with full directions for exposure and development, of all sizes and in any quantity, at the following prices:--
Per Doz. | Per Doz. s. d. | £. s. d. 4¼ × 3¼ 5 0 | 7 × 6 0 14 0 5 × 4 6 6 | 8½ × 6½ 0 18 0 5½ × 3⅜ 6 0 | 9 × 7 1 1 0 6¼ × 3⅜ 8 6 | 10 × 8 1 6 0 6½ × 4¾ 8 6 | 11 × 9 1 13 6 6¾ × 3¼ 8 9 | 12 × 10 2 0 0 6 × 5 8 6 | 15 × 12 4 0 0
LARGER OR OTHER SIZES TO ORDER.
The advantages of a certain and simple Dry Collodion Process are so obvious to those who have practised Photography in the open air, that we feel it is merely necessary to introduce the above list to their notice with as few remarks as possible.
We would, however, mention a few particulars connected with the process for the information of those who have not hitherto practised the Dry Collodion process, as detailed by Mr. Long.
The plates as prepared for sale, are hermetically sealed in an envelope perfectly impervious to air and moisture, they can therefore be exported to any climate without risk of deterioration.
Plates prepared by Mr. Long's process will keep sensitive for almost an indefinite period, and can be developed at any time without regard to the date of exposure; this, it will be seen, is of immense advantage to the tourist, as he can delay the development of the whole of his plates until his return.
To those Photographers whose inclinations or want of leisure will not admit of their carrying through the first preparation of the plate, these Dry Sensitive Plates will be found invaluable, enabling their whole energy to be directed to the more careful selection of subject.
The plates being dry, there is no danger of dust settling on their surfaces; this point will be appreciated by every Photographer.
The development of the pictures can be conducted in any room whence the light can be excluded--as the process is simple and clean--three dishes being the only requisites in point of apparatus.
To Officers, Engineers, and Architects, these Dry Plates offer a desideratum of no small value, as they are _always ready for use_, occupy very little room in travelling, and can be used under circumstances which would preclude the adoption of any process that had to be carried out on the spot.
* * * * *
BLAND & LONG,
Photographic Instrument Makers to the Queen
153, FLEET STREET, LONDON.
THE
=DRY COLLODION PROCESSES.=
* * * * *
Messrs. BLAND & LONG have invented the following simple means of
=CHANGING THE DRY COLLODION PLATES=
while working in the fields. The plan has been in use for some time, and answers perfectly.
* * * * *
_Price according to size._
_Adapted to Stereoscopic Camera, 15s._
* * * * *
DESCRIPTION AND DIRECTIONS FOR USE.
No matter what process we employ to retain the sensitiveness of our plates, it is most objectionable that the glasses should be made to slide by their gravity from the plate-box to the slide; for if we employ either honey, glycerine, or oxymel as preservative agents, the chances are considerably in favor of an amount of dust settling on the surface, the dust being in a great part formed by the attrition of the roughened edges of the plate against the plate-box. Another inconvenience attending the use of a box when the plate has to slide, is the danger that exists under that arrangement of ripping the film from the edges of the plate by the friction against the groove in the box which holds it. These may appear very trivial matters, but they are nevertheless great drawbacks to successful operations.
We may mention that the plan we are about to describe is equally applicable to all Cameras of moderate size. We will, however, take our description from the form of apparatus adapted to a double lens Stereoscopic Camera.
The Camera (A) is furnished at its back with two wires (B). On these wires slides the plate-box (C), which has previously been fitted at its sides with two sockets (D). Just inside the back of the Camera box is a spring (E), and on the top of the Camera is a button (F), which secures the dark slide in its place.