CHAPTER VIII.

=THE COLLODIO-ALBUMEN PROCESS.=

[Sidenote: COLLODIO-ALBUMEN PROCESS.]

This is a process, invented by Dr. Taupenot, for obtaining negatives on glass, which bids fair to outrival all others, being easy of manipulation, and giving results of the most exquisite minutiæ and beauty. Glass plates, when prepared and excited by this process, may be kept at least a fortnight before being developed, and these plates when exposed in the frame may be developed immediately, or kept for days before commencing this operation. Indeed it is quite possible to prepare and excite a number of plates before leaving home to go on a tour of twelve or fourteen days; to expose the plates at any time or place during the journey, and bring them home to be developed.

The manipulation may be said to consist of nine distinct operations.

1. Cleaning the plate. 2. Coating with iodized collodion. 3. Exciting the collodion film. 4. Coating with albumen. 5. Exciting the albumen coating. 6. Exposure in the camera. 7. Developing the image. 8. Fixing the image. 9. Varnishing the plate.

Before describing these operations, I propose to give clear directions for preparing the necessary solutions, merely promising that, where I have deviated from the inventor's plan, it has been after performing careful experiments, to test the merits of the two modes of proceeding.

The necessary solutions for this process are:

Collodion bath solution. Iodized collodion. Iodized albumen. Albumen bath solution. Pyrogallic solution. Silver developing solution. Fixing solution.

_Collodion Bath Solution._

Nitrate of silver in crystals 1 ounce. Iodide of potassium 2 grains. Distilled water 16 ounces. Alcohol 2 drachms.

Dissolve the ounce of nitrate of silver in two ounces of the distilled water, and the two grains of iodide of potassium in one drachm of distilled water; mix the two solutions and shake well together until the precipitate which is first thrown down is re-dissolved; when this takes place, add the remaining fourteen ounces of distilled water, and the two drachms of alcohol. On the addition of the water a turbidness ensues, which must be removed by the solution being very carefully filtered through filtering paper; and the filtered liquid should be clear and transparent, free from any deposit or floating particles, and must possess a slightly acid reaction of test-paper.

In order to ascertain if the solution thus prepared possesses the necessary amount of free acid without superabundance, proceed to test and to correct it, if necessary.

_Iodized Collodion,_

The collodion to be used in this process must be one yielding good _negative_ pictures--that supplied by Home & Thornthwaite under the name of negative collodion answers admirably. This is supplied either ready iodized, or the collodion and iodizing in separate bottles. As this collodion becomes less sensitive after being iodized a fortnight, it is advisable to iodize no more than will be used in that time--therefore, obtain the collodion and the iodizing solution separate, as the mode of iodizing this collodion is very simple. Half an ounce of the iodizing solution is mixed with one ounce and a half of collodion, and the mixture allowed to settle twelve hours before being used; and it is even advisable to pour off the clear solution into a perfectly clean bottle, in order to get rid of any insoluble matter which may fall to the bottom.

_Iodized Albumen._

White of egg (free from yelk) 10 ounces. Honey 1 ounce. Iodide of calcium 2 scruples. Yeast 1 tablespoonful.

Mix these together in a tall glass jar, or wide-mouthed bottle of at least one pint capacity; tie a piece of paper, pierce with small holes over the top to keep out dust; then place the whole near a fire or other warm situation, where the temperature is not lower than seventy degrees, or higher than ninety degrees. In a few hours fermentation commences, which is evident by the formation of bubbles of gas, rising through the liquid. This action continues for five or six days; when it ceases, pour the whole on a paper-filter contained in a funnel, underneath which must be placed a bottle to receive the liquid as it passes through. The fluid being of a viscid nature filters slowly, generally occupying twelve hours.

The filtered liquid is the "iodized albumen," which is said by Dr. Taupenot to keep good for years. It must be carefully preserved from dust or contact with any substance, as the success of the picture depends materially on the condition of this albumen.

_Albumen Bath Solution._

Nitrate of silver 1 ounce and a half. Acetic acid, glacial 1 ounce. Distilled water 16 ounces. Animal charcoal 2 drachms.

Dissolve the nitrate of silver in the distilled water, then add the acetic acid and animal charcoal, and keep in a closely stoppered bottle for use.

_Pyrogallic Solution._

Pyrogallic acid 15 grains. Glacial acetic acid 2 drachms. Alcohol 2 drachms. Distilled water 7 ounces.

Dissolve the pyrogallic acid in the distilled water, and then add the acetic acid and alcohol.

_Silver Developing Solution._

Nitrate of silver 1 drachm. Acetic acid 2 drachms. Distilled water 7 ounces.

Dissolve the nitrate of silver in the distilled water, and then add the acetic acid.

_Fixing Solution._

Hyposulphite of soda 2 ounces. Water 1 pint--dissolve.

_Varnish._

The varnish best adapted for this purpose is that supplied by Home & Thornthwaite, and termed negative varnish.[H]

[Footnote H: In this country, Humphrey's Collodion Gilding is the article in almost universal use.]

_Cleaning the Plate._

The plates must be cleaned in the usual way, merely premising that extra care must be observed to remove every impurity, as cleanliness in photography is an absolute necessity.

In order to hold large plates whilst being cleaned, the "screw plate-holder" is exceedingly useful. This is made in three sizes, and adapts itself to all sized plates.

The small size is useful for plates up to 7 inches by 6.

The second size is for plates up to 10 inches by 8.

And the third size for plates up to 14 inches by 10.

_Coating with Iodized Collodion._

The plate having been thoroughly cleaned, and received its final polish by the use of a prepared chamois leather, is coated with negative collodion, which has been iodized at least twelve hours, and allowed to settle.

_Exciting the Collodion Film._[I]

[Footnote I: This and subsequent operations (except exposure in the camera) must be performed in a dark room.]

After the ether has evaporated, and the surface of the collodion appears set, the plate must be laid, collodion side upwards, on a glass dipper, and plunged with _one downward movement_ into a bath filled to within an inch of the top with collodion bath solution, made as described at page 190, which must be carefully filtered through filtering paper before being used. After the plate has been allowed to remain in the bath one minute, it is lifted out three or four times, in order to facilitate the removal of the oily appearance the plate now presents. When the surface appears wetted uniformly, on being drawn out of the solution the plate is removed from the dipper, and the excess of solution drained off, and is then placed collodion side upwards, on a fixing stand, and distilled or filtered rain water poured over the surface, so as to remove as much as possible of the bath solution from the surface. The plate is now removed from the fixing stand; the back well washed with water, and then placed nearly upright on blotting paper, with the face against a wall for _one minute_ to drain.

_Coating with Albumen._

Having allowed the plate to drain one minute, place it again on a levelling stand, with the film upwards, and pour over it as much of the iodized albumen as the plate will hold, from a glass measure containing not more than enough of the albumen to coat two plates with, pour off the excess into the measure, and again cover the plate with albumen three separate times; ultimately drain off as much as possible of the excess of albumen, and place the plate nearly upright against the wall, with the coated side inwards, to dry, which takes place in an ordinary temperature in about one hour.

In coating with albumen, the presence of air-bubbles or dust must be guarded against. The former can be easily done by taking care, in pouring the albumen into the measure and on the plate, not to pour so as to generate air-bubbles in the liquid. But should any be detected, hold the plate horizontally and give it another coating of albumen, then incline the plate so that the bulk of the liquid shall pass over and carry off the bubbles with the running stream. Dust on the plate must be prevented by operating in a room as free from this photographic enemy as possible.

In order to render the coating of albumen as uniform as possible, the plate must stand to dry on two or three layers of filtering paper and the upper surface must touch the wall at _one point only_ and not to be allowed to rest against it along its entire upper edge.

When the albumen coating is _thoroughly dry_ (and not till then), the plate is ready to be excited, but if more have been prepared than are likely to be used for taking pictures on during the next ten days or fortnight, they may be stowed away in a plate box, ready to receive the sensitive coating at any time. The author's experience has led him to believe that these albumenized plates will keep good any length of time, as plates which had been coated a month, when excited, exposed, and developed, appeared to possess all the properties of recently prepared plates.

_Exciting the Albumen Coating._

Prior to the plates being excited they must be _thoroughly dry_ and free from any particles of loose dust on the surface, back, or edge. Sufficient of the albumen bath solution, page 192, must be filtered through filtering paper to fill a dipping bath of the required size, so that the plate can be immersed in it.

The careful filtering of the fluid is very necessary in order to free it from any floating particles, and to separate the animal charcoal.

The plate is now taken and laid, albumen side upwards, on the dipper, and then lowered into the bath with one steady downward movement, where it is allowed to remain one minute; it is then taken out, the excess of liquid drained off, and placed on the fixing stand, with the albumen surface uppermost, and a stream of water poured over it for at least one minute, so as to remove every particle of the bath solution. This complete washing is very necessary, in order to prevent stains in the after development, which invariably takes place around the edges, if not thoroughly washed. The plate having been thoroughly washed, is leaned against a wall to dry, or if required for immediate exposure, may be dried on a plate of heated metal or foot warmer, but in no case must the exposure in the camera take place until the surface is thoroughly dry.

_Exposure in the Camera._[J]

[Footnote J: Remarks as to the selection of the view, &c., are not given, as this can be effected by the individual taste of the operator, but care must be taken that direct rays from the sun shall not fall on the lens or enter the camera during the exposure of a plate.]

As has been before stated, this operation may take place immediately the plate is thoroughly dry after being excited, or a fortnight may intervene between the excitement and exposure, provided the plate is kept very carefully excluded from light and any chemical or sulphurous vapors, in a plate-box adapted for that purpose, with the sensitive surface towards the back of the box. When the exposure is about to take place, or at any time previously, the camera-backs may each have a plate placed in them ready for exposure; to do this, the camera-back must be taken into the operating room and the door closed, so as to exclude all white light. The hinged flap of the camera back is opened, and the prepared plate laid, with its sensitive surface downwards, or next the sliding flap, so that its corners may rest on the silver wire corners of the plate frame previously placed within the camera back ready to receive it. The hinged flap is now closed and kept from opening by turning the flap button over it; the sliding flap is examined to see that it is pushed closely down so as to guard any access of light, and it is then ready to be placed in the camera, and may be taken into the open air with impunity. Should the exposure not take place immediately, or, should the camera back have to be carried any distance, it is advisable either to wrap it up in black cloth, or secure the flaps from the chance of coming open during transit, by a stout string being tied around the back.

The focussing is conducted in the usual way and the cap replaced on the lens; the focussing glass is now removed and the camera back fitted into the same aperture, with the sliding flap next the lens. The sliding flap is pulled up to its fullest extent, placing the hand on the camera back to prevent it rising out of the camera with this action. The cap of the lens is then removed, so that the light may be admitted into the camera, and to fall on the sensitive surface of the plate. After the necessary time of exposure has taken place, the cap is replaced on the lens, the sliding flap is pushed down, and the camera back withdrawn from the camera; the plate can then be taken into the operating room to be developed, or this operation may be deferred for days or even a week, or more if convenient. The time of exposure in the camera varies according to the intensity of the light and the aperture and focal length of the lens; therefore, to give the exact time of exposure would be impossible, still it may assist the amateur if I give the time required in summer with full sunshine, and merely state that this time may be increased to double in winter or dull weather.

In the ordinary sunshine of a summer's day the time of exposure will be:

30 seconds with a lens of 4-inch focus and 1/2-inch stop. 21 seconds with a lens of 4-inch focus and 5/8-inch stop. 5 seconds with a lens of 4-inch focus and 1-1/4 inch aperture with no stop. 1-1/2 minute with a lens of 6-inch focus and 1/2-inch stop. 4-1/2 seconds with a lens of 6-inch focus and 2-1/4-inch aperture with no stop. 2 minutes with a lens of 8-inch focus and 1/2-inch stop. 1-1/4 minute with a lens of 8-inch focus and 5/8-inch stop. 3-1/4 minutes with a lens of 10-inch focus and 1/2-inch stop. 2 minutes with a lens of 10-inch focus and 5/8-inch stop. 5 seconds with a lens of 10-inch focus, 3-1/4-inch aperture, with no stop. 6-1/4 minutes with a lens of 14-inch focus and 1/2-inch stop. 4 minutes with a lens of 14-inch focus and 5/8-inch stop. 2-1/4 minutes with a lens of 14-inch focus and 3/4-inch stop. 8-1/4 minutes with a lens of 16-inch focus and 1/2-inch stop. 5-1/4 minutes with a lens of 16-inch focus and 5/8-inch stop. 2-1/4 minutes with a lens of 16-inch focus and 3/4-inch stop.

_Developing the Image._

The camera back is taken into the operating room, from which all white light is carefully excluded, the plate removed from the camera back, and laid, albumen side upwards, on the fixing stand; as much distilled water is now poured on it as the surface will hold, taking care that every part of the sensitive surface is covered with the liquid; allow the water to remain on the surface for one minute, then pour off and drain slightly; replace the plate on the stand, and pour over the surface so as thoroughly to cover every part, the pyrogallic solution (made as described at page 192, and carefully filtered just before being used); allow this to remain on the plate for one minute, then drain off into a perfectly clean measure, and add to it an equal bulk of silver developing solution, page 192; mix these thoroughly together with a glass rod, and then pour the mixed liquids over the plate; allow them to rest until the picture begins to appear, which generally takes about from three to five minutes; then pour off and on repeatedly, until the developing fluid becomes opaque, which then contains floating particles, and these, if allowed to do so, would settle on the plate, to the injury of the picture; but this may be prevented by brushing the surface with a camel's-hair brush frequently during the development. When this opacity of the developing fluid takes place, drain all the fluid off the plate, and thoroughly wash with water; then mix another quantity of pyrogallic and silver developing solution in the same proportions as before, and pour this on and off the plate as before, until the picture appears sufficiently intense, and the middle shades well brought out; when this takes place drain off, and wash with water, so as to clean the surface thoroughly, and the plate is then ready for the next step, "fixing the image."

Should the picture begin to develope in less than three minutes after the application of the mixed developing fluids, thoroughly drain the plate, and wash well with water, then continue the development with a solution of three parts pyrogallic solution and one part silver developing solution; but should the picture not begin to appear in five minutes, the addition of half a drachm of the albumen bath solution to each ounce of mixed developing solution will be necessary, in order to obtain the middle shades and the required intensity. It may be stated, as a guide, that the best negatives which the author has produced occupied from ten to twelve minutes in developing.

_Fixing the Image._

The plate, having been thoroughly freed from the developing fluid by careful washing, is now placed on the fixing stand, and the surface covered by the fixing solution, made as described at page 192, being poured over it. In a few seconds the yellow opalescent color of the film will begin to disappear, and its complete removal may be hastened by blowing gently on the plate, so as to disturb the fluid.

When every particle of yellowness has disappeared, the fixing solution is drained off, and the surface _thoroughly_ washed, and it is then leaned against the wall to drain and dry.

_Varnishing the Plate._

The plate, being thoroughly dry, is ready to receive a coating of transparent varnish.[K] in order to protect the albumen surface from injury during the printing process. To do this effectually the plate must be held before a fire, or over a lamp, until it is slightly warm all over; then pour over its surface the negative varnish, in the same manner as collodion is applied; allow the superfluous varnish to drain back into the bottle; hold the plate again before the fire until the whole of the spirit is evaporated; and, when cold, the plate is ready to be printed from, so as to produce any number of positive pictures on paper.

[Footnote K: Humphrey's Collodion Gilding is the best for this purpose.]

It will be observed, that in describing this process, the operator has been supposed to be so situated, that in case a second view of the same spot were required, he could return to his operating room, remove the plate which had been exposed, from the camera back to the plate box, and place another in the camera back, ready for taking another view. But, unfortunately, this is not at all times practicable. We, therefore, require some means of removing the plates, after being exposed, from the camera back into the plate box, and substituting others in their stead, whilst we are in the open air.

In order to effect this, the "field plate box" has been devised by the author, by the aid of which the plates may be removed from the box, exposed in the camera, and again returned into the box, without any possibility of access of light falling on it.

This box is but a trifle larger than the ordinary one, and is furnished with two sliding bottoms, working in grooves, one over the other; the lower bottom has a grooved channel, into which the side of the camera back slides; the camera back has an aperture through the side, closed by a narrow slide, and the lower bottom of the field box has a corresponding one. We now suppose the field box to have been previously filled with excited glass plates, having their sensitive sides towards the back of the box, and the box lid closed. The bottom slide is now pushed on until the aperture is in a line with any particular groove of the field box (which position is indicated by a numbered scale and index point). The camera back is then slid on to its place on the field box, so that the hinged flap is towards the front of the box, and its narrow slide drawn out. The upper slide is then withdrawn, and the box inclined, so that the plate in that groove opposite the aperture in the lower slide, may pass through into the camera back. When this has taken place, push in the narrow slide of the camera back, invert the box, and push in the inner slide; then withdraw the camera back from its channel, and expose the plate in the camera. When this is done, slide the back again into its channel, draw out the inner box slide, then the narrow camera back slide, invert the box, and the plate will then leave the camera back and pass into the field box, occupying the same groove as before.

In order to get out another plate, slide the lower bottom, so that the index points to the number on the scale, as that of the groove in which the required plate is situate. Then proceed as before directed.