There are a thousand and one formulæ for developing solutions for the wet plate, but they are all composed of protosulphate of iron or a compound thereof, acetic acid, and water, with the addition of some organic substance, such as sugar, rock candy, glycerine, etc. etc.
The development of a negative is nothing more than the deposition of metallic silver in a state of fine sub-division upon a base of the same metal, which is the image latent in the collodion film after exposure in the camera. And it is supposed that the finer the depositp34secured in the development the better will be the chemical effect and printing quality of the resulting negative. Therefore, the use of organic bodies in the developer is supposed to effect or induce a finer deposit. The careful observer, however, will soon discover that the success of the development depends more on the time of exposure, the temperature of the developing solution and the condition of the bath, than upon any adventitious aids, such as rock candy, etc.
A developing solution, composed alone of an aqueous solution of protosulphate of iron and acetic acid, can be made to produce the finest effects possible to the process.
Half fill with protosulphate of iron a wide mouth 64 oz. bottle, fill up full with water, set aside to dissolve, shaking the bottle once in awhile, so that the water may become saturated. Put a small glass funnel on a stand, so that you can place under it a 16 oz. bottle; fill the 16 oz. bottle with water and enough of the strong iron solution to make a twenty grain to the ounce solution, add one ounce of acetic acid, pour all into the filter and place the bottle beneath the funnel to receive it. This filtered solution is the developer for negatives.
Some experience is necessary to enable one to develope a negative properly and secure the best results.
Holding the plate in the left hand, take the developer bottle in the right, hold it over the plate near the left hand, let the first finger of the right hand rest against the edge of the plate, tilt the bottle so that the developer will run on the plate; at the same time movep35the right hand toward the other end of the plate rather quickly, letting the developer run in a steady, but not copious stream; deflect the plate with the left hand at the same time, so that the solution will flow from you in such a manner that the whole surface of the plate may be covered with the liquid at nearly the same time as possible. Now set down the bottle and keep the plate in motion, so as to cause the solution to have an equal action on every part of the surface. Very soon the image will appear and brighten, until every part of the detail comes out, and when it begins to look as if fading away or becoming less distinct the development is finished.
This can be ascertained with more certainty at this time by holding the plate so as to be able to look through it toward the light, so as to examine its density, remembering that the high lights should be quite dense and the medium shadows be full of detail. One very soon learns to know the proper density.
The plate should be now very thoroughly washed, to free the surface from the iron before fixing.
Great care should be taken in this manipulation to cover the plate quickly with the solution, holding it all on the plate. As the development is made by the precipitation of the free silver on the surface of the film upon the latent image, none of the free silver should be washed from the plate by a flood of developing solution carrying it off the surface.
Hyposulphite of soda is generally considered to be the most suitable fixing agent for negatives, although some prefer cyanide of potassium.p36
The hyposulphite, however, is the safest, both for the plate and for the operator. One pound of hyposulphite of soda to a gallon of water will make a solution of a suitable strength to clear a negative as rapidly as is necessary, and it should be contained in a flat dish. When from much use the fixing solution becomes muddy, it should be thrown into a suitable receptacle for liquid wastes, as it is rich in silver.
Leave the negative in the fixing solution until all the iodide of silver is dissolved from the film, and no trace of the yellowish deposit can be seen by transmitted light.
When the negative is thoroughly cleared, if it is found that it lacks density or, in other words, is not intense enough, wash it very carefully to free it from every trace of the soda solution, and then proceed to strengthen it in the following manner:
Keep near at hand in a 64 oz. bottle this solution:
and in a small bottle a ten-grain-to-the-ounce solution of silver nitrate.
When a negative is to be strengthened, from the large bottle take enough of the solution to cover the surface; to this add a half dram of the silver and flow it over the negative.
A change of color will at once take place in the film, which will become darker as the silver deposit becomes heavier; if one application is not enough to secure the required density, wash the plate and proceed again, as before.p37
Negatives may be strengthened before fixing, if it is found necessary, by flowing the surface with the weak silver solution and afterwards using the ordinary developer.
When one has become accustomed to the work, and can tell that the negative is not dense enough before fixing, it is the best plan to re-develop before fixing.
The mercurial intensifying solution for dry plates is very nice for wet plates.
Having described the positive and negative collodion process, there remains to give an account of the latest and greatest achievement in photographic progress.
The history of dry plate photography comes within the last ten or fifteen years, and being so recent and so fully written up in current photographic literature, space in this work will not be taken for a full account of the rise and progress abroad and at home of this wonderful improvement in photography, but instead will be given some formulæ for the preparation of Gelatino Argentic Emulsion, and the most approved methods of working it.
The shortening of the time of exposure for sittings in the studio from one-tenth to one-twentieth of the time required for the old wet plate process, at its best, has rendered the dry plate such a power in the hands of the photographer as to have caused it to be almost universally adopted in the studios of this country, and has practically displaced the wet process in the field and for all out-door photography.p38
Since the introduction of the new process into the United States, the preparation of rapid dry plates has been and remains now in the hands of certain prominent firms, who, from the skill they have acquired and the advantages they derive from all the machinery and conveniences that large capital enables them to procure, are enabled to supply fully the demand with a much better article than could be had were each consumer to manufacture for himself. In fact, if the photographer were compelled to manufacture his own dry plates there would be a very different condition of affairs at the present time.
Gelatine is a substance so susceptible to change from the action of our climate, with its varying temperature, that of a large number who have attempted to make dry plates for the trade, many have completely failed, some of them after a partial success; and others after spending thousands of dollars never could make two batches of emulsion alike; and then again the keen competition of the successful concerns has reduced the profits to not more than fair returns to a precarious business.
There are many, no doubt, who would be glad to experiment in this field, especially among amateurs, and it is for the benefit of such that certain hints and formulæ are given in this connection to enable them to make, if successful, their own plates.
The formulæ herewith given are selected from a large number published in the German, English and American journals, and while good dry plates may be made by either of them, yet it is doubtful if the highest success would repay the outlay.p39
A careful study of the published formulæ and the current literature on the subject of Gelatino-Bromide Emulsion will disclose the general principles on which they are based.
A certain amount of bromide of ammonium or potassium (preferably ammonium, on account of its greater uniformity and purity) and nitrate of silver are dissolved separately, and mixed together in a thin solution of gelatine, at a moderately warm temperature. Great sensitiveness is obtained by a long exposure to the same warm temperature, or by the addition of a small amount of ammonia, and raising the heat to the boiling-point for from a half to a full hour; when it is cooled more gelatine is added and the whole allowed to congeal or set, when it is reduced to shreds, and washed in cold water to remove the excess of the preponderate salt.
The sensitiveness of the emulsion is said to depend upon the fineness of sub-division of the grain of the bromide of silver in the presence of the gelatine. This extreme fineness is secured by long emulsification, or by the use of ammonia and a boiling heat.
The strength and tenacity of the emulsion depend on the quality of the gelatine, and its freedom from deterioration during the process of emulsification and the subsequent washing. A soft gelatine is suitable for the process of emulsification; afterwards a hard quality is used to give body and resistance.
The presence of free bromide or of free nitrate of silver in the finished emulsion would be fatal to its usefulness; therefore, as both of those salts are easily soluble in water, they must be got rid of by washing; consequently, before washing, the mass of jelly shouldp40be induced by the use of a refrigerator to set firm and hard, so that it may be broken up into shreds for washing, and the smaller the shreds the less washing they will require.
Of the following formulæ the first two are copied from English photographic year books, and are believed to be reliable; the others are by Dr. Eder, the greatest German authority on gelatine emulsion, and they are comparatively simple.
PAGET PRIZE.
NO. 1.
NO. 2.
Twenty minims of No. 1 solution are introduced into the whole of No. 2, and the Gelatine is left to swell.
In another glass vessel 330 grains of nitrate of silver are dissolved in 3 ounces of distilled water; a small quantity, about two fluid drachms, of the latter is poured into a test tube and diluted with an equal bulk of distilled water.
The solution of the bromo-gelatine is then rendered complete by immersing the bottle in hot water, and the dilute silver nitrate is added all at once.
The bottle is then shaken and the remainder of the strong silver solution added in quantities of half an ounce at a time, shaking the bottle as before after each addition.p41
The emulsion is then boiled for fifty-five (55) minutes, and when cooled down to 90 degrees F., one ounce of gelatine, which has been previously swelled and dissolved in water so as to measure four ounces, is added and put away in a cold place to set.
When set, squeeze through coarse canvas into cold water one half gallon and ¼ lb. salt; let it remain for five minutes, then wash thoroughly.
The addition of two ounces of alcohol and enough water to make up to twenty ounces completes the process.
In the preparation of this or any gelatine emulsion the work may be carried on in daylight as far as the mixing of the bromide and silver, which must be done in a dark room by the aid of a lamp or gas light shaded by orange or ruby glass. Sufficient of this non-actinic light may be admitted to enable the work of washing the emulsion, and afterwards the coating of the plates, to be carried on with ease and comfort, as the emulsion when wet is only half as sensitive as when dry.
JARMAN.
Dissolve in two jars in a vessel of water heated to 140 degrees F., stir each solution well with a separate rod or strip of glass, and when equally heated to 140p42degrees the silver may be poured in a gentle stream into the gelatine gum solution by the aid of a safe light.
When all has been mixed and thoroughly stirred, cover the top of the dish and allow the temperature to be at 140 degrees for eight hours, occasionally stirring the emulsion during that time, which should be done in the dark.
At the end of that time there should be weighed out, of Nelson's soft gelatine 250 grains, and of French hard gelatine 150 grains.
This 400 grains of gelatine must now be added to the emulsion, and occasionally stirred until all of it is thoroughly dissolved and incorporated with the emulsion, which will take about a quarter of an hour; it is then poured out in a clean 12×10 deep porcelain dish to set, and should be allowed to set for forty-eight hours, when it may be wrung through a piece of coarse canvas and allowed to fall into a solution of
Let it remain in this for five minutes, then strain through a horse hair sieve and wash it well for an hour and a half. Allow the shreddy emulsion to drain well in the sieve for about a quarter of an hour; at the end of that time place it in a clean stone-ware jar to melt, with the addition of four drachms of saturated solution of nitrate of potash upon melting, which may be done by setting the jar into a dish of water at a temperature of about 120 degrees F.
It will be found on measurement to be nearly 25 ounces of emulsion; as soon as it is ready for filtering four ounces of methylated spirit may be mixed with it,p43to which have been added four drachms of an alcoholic solution of tannic acid, made by mixing ten grains of tannic acid with one ounce of alcohol; this is to prevent frilling.
The rapidity of the plates will be about eight times that of a wet collodion plate, which for all ordinary purposes will be as rapid as could be desired.
Dr. Eder, the distinguished German scientist (who is a great authority on gelatine emulsions, and has published a book on this subject), gives the two following formulæ:
EDER.
Dissolve the silver in water and precipitate it with ammonia. Continue the addition a few drops at a time, until the brown oxide of silver re-dissolves and the liquid looks as bright as pure water; the strength of the ammonia is immaterial.
The nitrate of silver may be warmed to 93 degrees F., and poured into the bromized gelatine a little at a time, continually stirring with a glass rod. Rinse the silver bottle with 10 c. c. about 1½ drachms of water and add it to the emulsion, place the bottle containing the emulsion in a basin or saucepan of water heated to 90 degrees F., leave it therein from 15 to 30 minutes without further heat; after 30 minutes the emulsion is ready to be congealed previous to washing.
This emulsion never fogs, but it is imperative thatp44in no part of the progress the temperature should exceed 100 degrees F., and it is a safe rule not to go beyond 90 degrees F. It is recommended to use French gelatine.
EDER.
The bromide of potassium must be pure and not alkaline, ditto the gelatine.
The bromized gelatine must be melted at 140 to 160 degrees, and then add 77 grains of silver nitrate in one ounce (plus) of water. The silver may be warmed to the same temperature as the gelatine, but this is immaterial. Rinse the silver bottle with three drachms of water and add it to the emulsion. The bottle with the emulsion is now put in a saucepan partly filled with hot water, covered to exclude all light, and the water in the saucepan set boiling, which should be continued for 25 to 30 minutes, then both water and emulsion cooled down to 90 degrees F., then add 340 minims of ammonia, stirring it thoroughly through the emulsion, which should be left for from 30 to 40 minutes at a heat of 90 degrees F., then it is ready to set and wash.
Dr. Eder says this last is quicker and better for portraits.
Any form of room that has running water in it, if there is a window, the better, unless the work is donep45at night. If in the daytime, shade the window with heavy red orange paper; if gas is used, shade the flame with a ruby globe or chimney, and cut a piece of tin to fit in the pipe below the burner to cut off rays of light falling through bottom opening of globe or chimney.
If there is no gas purchase a dry plate lantern.
Emulsion in the jelly and when wet on the plates is only half as sensitive as when dry, so that it is not necessary to distress one's self working in the dark.
When the silver and bromide are brought together and mixed, it should be done in this dark room. The solutions are poured into a glazed earthenware bottle, which can be tightly corked. When it is required that the emulsion should be heated, put the bottle into a tin pail, fill the pail with hot water and put on the cover and heat in any convenient manner; when it is necessary to examine the emulsion, remove the pail and contents to the dark room.
A thermometer for testing heat in liquids should be used to regulate the temperature.
A deep porcelain tray is the best dish for holding the emulsion, while it sets previous to washing. To prevent the emulsion from adhering to the tray it may be waxed carefully, but leave no surplus; when the emulsion has set as firmly as it will, it may be cut up into very small squares for washing, but probably the best way is to squeeze it through the meshes of very coarse canvas, such as ladies use for embroidering on with wool. The shreds may be permitted to fall into a fine horsehair sieve placed in a pan of very cold water and allowed to soak for a time, when the sieve may be raised, and the water will in a short time drain awayp46from the shreds. This may be repeated until the water, when tested with silver solution, gives no precipitate of bromide.
After the emulsion is washed it must be melted and filtered before it can be used to coat plates. These manipulations must be performed in the dark room. For melting the emulsion use a small oil stove placed in a tin box, the open side placed to the wall; set the dish containing the emulsion on the tin box over the heat; or, a more perfect arrangement is to take a tin or sheet iron bake-pan, make a hole through the bottom near one end, and into the hole fix and solder a tin funnel, into which you can put a glass funnel that will hold a pint or more; set this pan on the tin box containing the oil or gas stove, the end of the pan containing the funnel projecting over the tin box towards you; fill the pan with hot water, which the heat of the stove beneath will keep hot; into it set the dish containing the emulsion to be heated or melted; when that has taken place pour into the funnel to filter, through loose absorbent cotton or a thin piece of chamois skin or flannel, as you prefer; the funnel will be kept warm by the hot water in the pan surrounding it.
Filter into a pitcher with a lip suitable for pouring from, or a small earthenware teapot would be better. You would be using the emulsion from the bottom, and thus avoid air bubbles; when all is filtered set the pitcher or pot into the hot water to keep of an even temperature.
Soak the glass in strong lye or potash for a time, then wash carefully and put into acid, then washp47again and albumenize with the white of one egg to six ounces of water without ammonia. The plates should be slightly warm when being coated.
Hold the plate in the left hand, as you would for coating with collodion, flow with emulsion as you would with collodion, letting the surplus flow off the right hand lower corner, but do not let more than the gross surplus run off; retain enough to make a rather thick film; now move the plate so as to facilitate an even distribution of the film, then set the plate on the leveled cooling table.
This table should be a large slab of marble or slate with a perfectly plain and level surface; before using it should be cooled by placing ice or a refrigerating solution on it. The coated plates are laid on this level table, where the cold soon chills the emulsion, causing it to set, when they may be set up in racks and placed in the drying room or box, where in the course of a few hours, if the conditions are favorable, they will dry and are then ready for use.
The drying room, or box, as the case may be, must be kept cool, and if any current of air is induced it should be cool and constant, so that the drying may proceed with perfect regularity until the process is complete. Should the drying by any means be checked a line will be formed on the plate, showing where the drying stopped for the time.
Plates may be dried by a current of warm air, butp48they are much more likely to frill during development; and a very little heat will melt the coating.
If the plates are dried by an induced current of air, the process may be hastened by placing dishes, filled with chloride of calcium, in the air passage to the drying box or room. The chloride will absorb all the moisture from the air passing over it, and the dry air will take up the moisture from the plates.
When the chloride of calcium becomes too damp for further use, place the dishes containing it in an oven and drive off the moisture by heat, when the dry calcium may be again used. By employing such means the plates may be dried in a few hours.
After the plates have become dry, they should be packed in good light-tight boxes and kept in a dry room until wanted for use.
Dry plates, ranging in rapidity from one-tenth to one-twentieth the time necessary for a wet collodion plate, are now commonly used in the studios of this country. Of course, plates of such extreme sensitiveness require great care in handling, and absolute freedom from any umpremeditated exposure to white light is necessary to their successful use.
It is therefore necessary that the dark room should be remodelled to suit the requirements necessary to the successful handling of such extremely rapid plates, and in this connection it is proposed to describe the necessary changes and alterations.
Any ordinary dark room may with little expense be fitted for dry plate work. First see that every chink or crevice which might admit white light is stopped orp49filled up, then fit the door or doors so that they will shut tight and remain closed.
For convenience of access to the room while work is proceeding, and for greater safety, it is well to erect a small porch or ante-room at each door, the entrance to which should be at right angles with the dark room door. The door to this porch and the dark room door should be fitted with springs to keep them closed. With this arrangement one can have access to the dark room at any time by closing one door before opening the other.
If the dark room is lighted by a window, it should be glazed with dark red orange glass, and if the exposure is toward the sun, it should be shaded with a green or ruby colored shade on a spring roller. If the sun never shines in the window, the shade is not necessary.
If the room is lighted by artificial light, the best way is to cut an opening in the wall or partition at the most convenient place, make a frame to fit or cover this opening, that will raise or slide, glaze it with red orange glass. On a shelf outside the opening place your gas-burner or lamp, with a large reflector behind, so as to reflect all the light through the glass into the room. If gas is used on the outside an argand burner will be the best, with a common white glass chimney for ordinary work, but for the most sensitive plates a light green or thin ruby chimney will be absolutely safe.
If a kerosene lamp is used, the common white chimney with full flame will be safe; and being outside, the room will not be heated by its flame, nor rendered offensive by its smoke and odor.
In front of the window or of the artificial light,p50erect a shelf or place a small table with a level top, which will support the developing dishes and bottles of developing solution, and on which the work of development may be carried on.
WASHING BOX.Washing Box
WASHING BOX.
If the room is so situated that neither window nor gas may be used in the manner suggested, then procure Carbutt's Developing Lantern, which is a most convenient lantern, not only for developing, but for other purposes. See figure.
The dark room should be supplied with running water, and the more generous the supply, the better, as a dry plate requires much washing, and a large stream will do the work much quicker than a small one.
In many instances, however, where running water may not be had, the washing box may be used with advantage. If running water is used, be careful not to use too much pressure; by attaching a rubber hose to the faucet and passing it over a nail or hook above, the pressure may be reduced so that a full but gentle stream falls upon the plate.
Safe closets should be provided to contain all sizes of plates; or the newp51made by Anthony & Co., may be used instead, both for unexposed and for exposed plates awaiting development.
NEGATIVE BOXESNegative Boxes.
NEGATIVE BOXES
The dark room should be supplied with the necessary apparatus, such as developing trays, which are of japanned tin, of glass or india rubber; see cuts,
JAPANNED IRON DEVELOPING TRAY,Japanned iron developing tray; Anthony's Glass Trays.
JAPANNED IRON DEVELOPING TRAY,
ANTHONY'S GLASS TRAYS,Japanned iron developing tray; Anthony's Glass Trays.
ANTHONY'S GLASS TRAYS,
or the patented article, the
GLASS BOTTOM DRY PLATE DEVELOPING TRAYS.GLASS BOTTOM DRY PLATE DEVELOPING TRAYS.
GLASS BOTTOM DRY PLATE DEVELOPING TRAYS.
p52
and also the dishes to contain the fixing solutions, which may be trays or upright, like silver-bath dishes.
THE COMMON SENSE TRAYTHE COMMON SENSE TRAY.
THE COMMON SENSE TRAY
is a capital dish to contain the hypo and clearing solutions and is not expensive, and can be had of all sizes. All these dishes should be kept scrupulously clean when not in use.
TN: Graduate
There should be Graduates of the 16 oz. and the 8 oz. sizes, and also a minim glass measuring up top53one fluid ounce, also one or more of Anthony's Combined Funnel and Filter, for filtering the various solutions.
ANTHONY'S COMBINED FUNNEL AND FILTER.ANTHONY'S COMBINED FUNNEL AND FILTER.
ANTHONY'S COMBINED FUNNEL AND FILTER.
There should be glass-stoppered bottles for containing the developing solutions, especially the pyro; also racks to hold the plates while drying;FOLDING NEGATIVE RACK.FOLDING NEGATIVE RACK.one finely adjusted scale with apothecary weights weighing to a ¼ lb.; one camel's hair-brush, 3 inches wide, for dusting the plates beforep54putting them in the holders for exposure, and also for removing sediment from the surface of the film after fixing and washing.
CAMEL'S HAIR DUSTERS.CAMEL'S HAIR DUSTERS.
CAMEL'S HAIR DUSTERS.
Thus fitted and furnished, the dark room is ready and well adapted for the most difficult dry plate work, and we will now proceed to the consideration of the
Every manufacturer of dry plates encloses in each box of plates packed for the market a formula for the development of the same.
The various manufacturers of dry plates, whose names will be found in the advertising pages in this book, each have a formula which in some respects differs from all the others, and it is but fair to the maker of the plate, that his formula should be used, unless the operator is of much experience and understands the requirements of each particular kind of plate.
Therefore, while formulæ are given in this connection, although they are known to be of the best, yet in the hands of inexperience they may result to no better advantage than the formula appropriate to the plate used; consequently, we do not urge their use above any other, but rather that to which the operator is most accustomed.
The alkaline pyro developer is now in general use among professional photographers in this country, and there remains no doubt that it is the best developing agent for dry plates that has yet been brought into use.
This developer is composed of pyrogallic acid andp55an alkali, either ammonia, sal soda, or carbonate of potash, which, in solution and of proper strength, forms the medium through which the pyro is applied.
To these is added bromide of potassium or ammonium, which is the restrainer, and occupies about the same position or performs the same function as acetic acid in the wet plate developer, and besides being a restrainer it greatly aids in securing intensity and printing quality; and when plates are overtimed in exposure its prompt use may result in securing a good negative.
Some plates require double the quantity of pyro that others do to produce the same quality of negative. After ascertaining the normal amount of pyro necessary to develop plates of a certain make, if it is desired to increase intensity add more pyro, if your plate is developing too intense or hard add more of the alkali.
No. 1.
No. 2.
Keep No. 2 in glass-stoppered bottle.
To develop one 8×10 plate, take of
Put the exposed plate into the developing tray andp56pour the solution upon it, making sure that all parts of the plate are covered, and no air bubbles fixed to the surface; keep the dish in motion and in a short time the image will begin to appear; if properly timed the high lights will show up promptly, and in due time all parts will appear, and when detail is seen in the shadows take the plate from the dish and examine it by transmitted light. Note the gradations of light and shade; if they appear properly balanced, the plate has been properly timed in exposure. Return the plate to the dish and let the development proceed until the image sinks well into the film and you see nothing very clearly as it lies but the blacks.
Time is necessary in this process to secure enough intensity, and this stage is the most difficult in the process, there being no means by which to judge with any degree of certainty the density of the image before you. It is better then to proceed too far than not far enough, as a slow printing negative is far better than one that is too thin and weak.[1]
[1]These directions apply to all dry plates except the Stanley, which can be developed to any required density at sight, and loses none in the fixing solution.
When the image has sunk pretty well into the film examine it again by looking through it, and note well its appearance, so that if it is about right when fixed you may remember how it appeared if you wish to increase or diminish the intensity of your next plate.
If the plate has been overtimed it will show up quickly, almost at once; when such is the case quickly pour off the developer and flow the plate with water, washing it well, then prepare more developer with nearly double the amount of pyro and a few drops of ap57strong solution of bromide of ammonium, which add to the 6 oz. of water and pour on the plate; then take half the usual quantity of the No. 1 solution in a graduate and pour it, a few drops at a time, into the developing tray, watching the action closely and keeping the solution in motion.
The negative at this time probably shows all the detail of the subject, but without any gradation of intensity. If the changes just described have been made promptly you will soon observe that the high lights will begin to gain in strength. Keep up the action by adding more of the alkali, drop by drop, until you can proceed no farther.
The chances are that you will secure a printable negative, but not a very good one; and if it is a portrait the best thing to do is to throw it away and make a new one.
The plate should now be very carefully washed previous to fixing.
Should the film show signs of loosening from the edges of the glass and swell so as to form folds or frills, take it from the water and immerse it in a solution of alum, which will harden the film and stop the frilling. Then wash the film again and put it in the
When the soda and alum are dissolved let it stand until all sediment settles to the bottom, then pour off the clear solution and use it to fix until from much use it becomes black and turbid, then make up and use a fresh solution.p58
The plate should be left in the fixing solution for fully five minutes after it appears thoroughly cleared, then take it out and wash until all traces of hypo are removed.
If the plate has not previously been in the alum solution it may now be put in the
Keep this solution in a flat dish, and after the plate has been washed from the hypo put it in this solution for two or three minutes; if there are any remaining traces of hypo in the film it will be decomposed, the film will be hardened and freed from color; when this is accomplished wash again and set the plate up to dry.
While the alkaline pyro developer is the best and gives the finest printing quality to negatives, there are many who prefer (for other reasons) the
No. 1.
Acidify with oxalic acid and filter.
No. 2.
Filter and add 60 drops sulphuric acid.
No. 3.
The developer is prepared by mixing together in ap59graduate the quantity necessary to cover the plate in the following proportions:
For instance, it will take about 8 ounces to cover an 8x10 plate in a flat dish; to make this quantity take of the
Always pour the iron into the oxalate solution, then add the bromide, and having placed the exposed plate in the dish pour the developer upon it, covering the surface of the plate as quickly as possible and removing any air bells that may stick to the surface.
Keep the solution in motion on the surface of the plate and in a short time the image will begin to appear, the high lights first, then the intermediate shades, last of all detail will be seen in the shadows. Now pour the developer off, take the plate out of the tray and look at the back of it. If the subject or image can be distinctly seen it may be considered finished and only needs to be washed and fixed.
If the plate has been over-exposed, which will be indicated by the image appearing quickly, wash off the developer with water, add more bromide to the solution and immerse the plate again.
If, on the contrary, the plate has not had enough time, it will be indicated by developing very slowly and with a very thin and weak image; when such is the case add more of the iron solution, however, not more than to make the proportion of the iron nearlyp60one-fourth of the whole solution. More than this proportion will cause a yellow precipitate, which will settle on the surface of the film and destroy it. If by this course you succeed in securing sufficient detail in the shadows, the negative may afterwards be strengthened.
It is as well, however, when a plate is found to be undertimed (and it is possible to make another from the same subject) to throw it away; it will scarcely repay further attention.
It will be seen that a considerable margin in time of exposure can be allowed and provided for. Yet none the less it is of the utmost importance to learn to give the correct and proper exposure to secure the finest results.
This, it is true, is not always possible, and as an under-exposed plate is lost, any error in exposure would better be in too much rather than in too little time.
It is said by some that by the use of citrate of soda almost any degree of over-exposure may be remedied, but there remains the fact that for a restraining agent to be of any value its application to a negative in development must be almost instantaneous upon the earliest discovery of the over-exposure.
When a large number of plates have been exposed and the first developed indicates that all have been overtimed, then a 50 per cent. solution of citrate of soda, used with judgment, might result in saving the lot.
When over-timing makes itself visible unexpectedly and it is feared that the development will have proceeded too far before the retarder can act, a good plan is to take the plate out of the dish and flow over it a solution of citric acid, containing a little chrome alum,p61which will immediately stop the action of the developer and give time to make other arrangements.
No. 1.
No. 2.
To use, take of
This will be enough to develop three or four 8×10 plates, if they are properly timed.
The above is one of the best forms of ammonia pyro developer; it gives negatives of very fine quality.
Many dry plates, on development with ammonia and pyro, show a green fog by reflected light, and a pink or red fog by transmitted light; this fog does not materially injure the printing quality of the plate, but spoils its appearance to the eye, and for that reason many establishments have given up the use of ammonia and in its place use soda or potash.
From the difficulty of judging when the development has reached the right point, in consequence of the opacity of the gelatine film, many negatives are finished before they have acquired sufficient density in development. As a result of this, much attention has been given to the discovery and preparation of redeveloping or intensifying solutions, many formulæp62for which have been published; among the best are the following:
Add to this a strong solution of Iodide of Potassium drop by drop, until the red precipitate begins to redissolve, then add a few grains of hyposulphite of Soda, or enough to clear the liquid.
When required for use pour part of this solution into a tray of a suitable size for the plate, add an equal amount of water, then immerse the plate and keep the solution in motion. You will immediately notice a change in the color of the film; take the plate out, and if it has gained enough strength, wash it and set it up to dry; if not, give it more.
It is proper to state that this process is more effective if the plate has been dried after development.
When the plate has been thoroughly fixed and fully washed, it will intensify by this method, without change of color by transmitted light, and it will have secured a lovely printing quality rarely seen even in the most perfect negatives.
This solution may be used until it is exhausted.
When dissolved, this solution is ready for application and can be used repeatedly.
The negative, after fixing and washing, is immersed in the solution until it turns white.p63
Now remove it and wash slightly, then immerse it in old ferrous oxalate developer and allow it to remain until it becomes black entirely through the film. This method gives fine results and good printing color.
Form the habit of noticing carefully the intensity of the illumination of the subject on the ground glass of the camera, so as to judge correctly the time of exposure, as much of the successful working of dry plates depends on the exposure; for although slightly under-exposed or much over-exposed plates may by suitable modification of the developer be saved and print good pictures, yet they will lack the glow and balance that are characteristic of the most perfect work.
Use a flat camel's-hair brush to remove any dust from the plate, before putting it in the shield for exposure.
Always keep your developing solution in motion on the plate.
Fix your negative very thoroughly; leave it in the hypo 5 or 6 minutes longer than it is apparently necessary.
Never use hypo after it becomes discolored or turbid and deposits a sediment.
Develop longer than you think necessary; a slow printing negative is preferable to a weak one.
Keep your dark room and its contents very clean and free from dust, and well ventilated.
No photographic establishment in these days is considered to be well equipped that does not employ a skillful retoucher and provide all the apparatus andp64conveniences for the proper performance of this very important branch of the art.
It is within the memory of many photographers when this work of retouching was done on the positive, and some establishments were compelled to employ a large force of skilled hands to work up and finish the crude productions of the camera and the printing frame.
After the introduction of the carte de visite portrait, and later the Imperial card, and the consequent reduction in price, the expense of this work became such a burthen to photographers that they were compelled to perfect their mechanical operations to the utmost extent, and by every means to endeavor to avoid it.
It occurred then to some one of the retouching artists to do this work upon the negative once for all, and from this beginning the art of retouching the negative has reached its present high position.
Retouching, like stippling or hatching in miniature, is a work of art, skill in which is gained only by assiduous practice controlled by good taste, and it is the special work of the artist and not of the photographer.