Reilly, James M. The Albumen & Salted Paper Book: The history and practice of photographic printing, 1840-1895. Light Impressions Corporation. Rochester, 1980.
|Ammonium chloride||15 g||combine and add to;|
|Glacial acetic acid||2 ml|
The mixture should be beaten in an electric mixer or blender for 3 minutes, or until the entire mixture has been converted to a froth. Allow the mixture to settle in a covered container for 24 hours. Strain the mixture through muslin; the liquid may have to be squeezed through the muslin with some pressure. Cover and refrigerate for one week. The albumen solution will remain useful for several weeks after the one-week aging period. The smell of the albumen and its color, sedimentation, etc., will reveal when it has decomposed too badly to use.
Fig. 22. An 1874 advertisement for Dresden paper in an American photographic book, The Practical Printer.
The basic mechanism of coating consists in filling a tray to a depth of approximately 2/3 to ¾ inch with the albumen solution and floating the paper on the surface for 1½ minutes. The choice of paper for albumenizing is somewhat limited, since paper of the type commonly used for the purpose in the 19th century is not readily available in art supply stores. A thin, smooth all-rag stock is necessary, and perhaps the closest approximation of the ideal that is available in most areas is Strathmore Series 500 drawing paper, one-ply, with the plate finish. Although it is somewhat heavier than the usual 19th-century rawstocks, this paper will perform satisfactorily.
To coat the paper, first condition both the paper and the albumen solution by allowing them to gradually come to the operating temperature of the work room. When ready to coat, filter the albumen through muslin and place it in a tray slightly bigger than the size of sheet to be coated. Immediately before a batch of paper is to be floated, it is helpful to add a surfactant such as Kodak Photo-FloTM 1:200 to the albumen solution. Use 4 ml of Kodak Photo-FloTM for each liter of albumen, and gently stir it into the solution, avoiding bubbles as much as possible. The purpose of the surfactant is twofold: first, it controls bubbles--one of the most troublesome aspects of the whole process--and second, it improves the runoff characteristics of the albumen during drying and promotes a more even coating. The commonly used jargon for surfactants in photographic coating plants is to call them "spreaders," which graphically sums up their benefits in the coating process.
Fig. 23. A drying rack for albumen paper.
The actual procedures and precautions of the floating process itself are the same as those described in Chapter 3 for plain salted papers. Albumen paper must be coated on one side only and cannot be immersed in the solution. With thin papers air bubbles trapped under the sheet will be visible as light circles on a dark background, and if they appear, the sheet must be lifted by one corner and the bubbles broken. With thicker paper the bubbles will not be visible through the sheet, so each sheet must be lifted off the surface and the bottom side inspected for bubbles. Floating paper requires a little skill, but it is not really difficult and experience is the best teacher. It is best to start with a sheet about 10 x 12 inches in size, since this leaves plenty of margin area when one 8 x 10 or four 4 x 5 prints are desired. The time of floating should be 1 to 1 ½ minutes. Time the process from the moment all bubbles are broken and the sheet lies flat on the surface of the solution. Lift the sheet slowly off the solution and hang it to dry by two corners along the long edge of the sheet.
The arrangements necessary for drying the sheets are the same as those for plain salted papers described in Chapter 3. One additional factor is present with albumen paper, however, and that is the effect of heat on the drying process. The higher the temperature of the drying environment, the faster will be the drying, and more importantly, the glossier will be the paper. Temperatures of 30 to 50°C were maintained in drying rooms in albumen paper factories in the 19th century. High temperature drying is not necessary, but it does offer a way to improve the gloss and depth of single-coated albumen papers. During the process of drying the albumen will collect along the bottom edge of the sheet. If this runoff is allowed to dry, a thick rind of albumen will form and make the sheets very difficult to work with in subsequent operations. In addition, the last droplet will take a very long time to dry. The remedy for this is to blot off the collected runoff with a cloth several times during the drying process. The sheets should dry in a relatively short time if this precaution is observed. When dry, the sheets should be placed in a pile and flattened under weights. This makes them supple and easy to handle in the further floating operations to come.
There will always be a slight difference in gloss and thickness of coating between the top half of the sheets and the bottom half because of the action of gravity in hanging the sheets to dry. The severity of this effect depends on a large number of factors, but it is usually not so pronounced as to render a batch of paper completely unsuitable for use. Obviously many of the characteristics of the finished prints depend on the thickness and glossiness of the coating of albumen; among these are the ultimate color of the prints, their brilliance and "depth," and the ease of toning and fixing. Toning and fixing are more difficult with thicker coatings because the albumen becomes increasingly less permeable as the coating thickness increases. As mentioned above, one of the most attractive features of albumen paper in the 19th century was its glossy surface and added "depth," so experiments were made to increase the coating thickness by using multiple coatings of albumen. It was soon learned that some form of hardening or coagulating step was necessary between coatings to render the first coating insoluble. Otherwise there was no gain in thickness or amount of albumen on the sheet, because the second coating step dissolved off the albumen remaining from the first coating operation.
There are three possible approaches to hardening the albumen between the first and second coating operations. The simplest and most widely used method in the 19th century was to store the paper in a warm loft for six months, during which time a slow curing process sufficiently hardened the albumen.- If a speedier result is desired, there are two "instantaneous" approaches. One is to subject the albumen to a current of steam, which in effect cooks the albumen and renders it insoluble. The other is easier and more practical; it involves briefly immersing the sheets in a 70% solution of isopropyl alcohol. Pure alcohol is too strong and unevenly coagulates the albumen layer, while too dilute alcohol solutions are not strong enough to coagulate the albumen before it partially dissolves into the water. Experience has shown that a 70% solution is the most effective. To prevent leaching out of the chlorides from the albumen, whatever chloride content is present in the albumen itself should also be added to the alcohol solution--if the albumen contains 2% ammonium chloride, so should the alcohol solution.
A satisfactory procedure to accomplish the hardening is simply to place the alcohol solution in a tray and slowly pull the sheets of albumenized paper through the solution and hang them up to dry. When they are dry they should be placed in a pile and flattened under some weights to make them easier to manipulate during the second floating operation.
Mark the edge of each sheet that was lowest when the sheets were hung to dry the first time. This marked edge will be hung as the top after the second floating on the albumen, in order to even out the coating and thereby compensate for the runoff effect.
Two coatings of albumen produce papers that are quite glossy and may even be so heavily coated that they are brittle and hard to tone. Double-coated paper usually produces better prints from thin negatives than single-coated paper does. For more information on this point, see Chapter 7. A large portion of the albumen paper sold after 1880 was of the double-coated variety. However, double-coated papers have a greater tendency to curl, and are harder to manipulate in sensitization and printing.
Once the sheets have been albumenized, they will keep very well if stored in a cool and dry place. If the sheets must be rolled for storage, it is better to roll them with the albumen side out so that the cracking of the albumen is minimized. To sensitize the sheets for printing they must not be excessively dry at the time of sensitization, because if too dry, they will not properly absorb the silver nitrate solution. A good plan is to place the sheets overnight in a damp location such as a basement, etc. This also tends to make the sheets more supple and easier to handle. Albumen paper should be floated on a 10-12% silver nitrate solution for 2 ½ to 3 minutes. No additives to the sensitizing bath are required in the ordinary course of printing. See Chapter 6 for complete information on the sensitization process and the management of the silver bath.
Of course, care must be taken during sensitization to make sure that no air bubbles are trapped under the sheet; bubbles prevent sensitization where they occur, and will cause white circles on the face of the finished print. The sheets must be very slowly and carefully lifted off the silver solution, since no silver solution should reach the back of the sheet, and also because if lifted too quickly, the runoff of sensitizer might cause uneven sensitization. Some old manuals recommend drawing the sheets over a glass rod as they are lifted free of the solution, but this is unnecessary if the sheets are slowly peeled from the surface. Mild heat may be used to accelerate the drying of the paper after sensitization, but the paper must not be allowed to become excessively dry at the time of printing. As is the case during the albumenizing steps, the silver solution which runs off the sheets when they are hung to dry must be blotted with blotting paper or a cloth. Not only does this speed the drying process, but it insures more even sensitization.
One of the most confusing things about researching the albumen printing process in 19th-century sources is the question of ammonia fuming. This was a procedure in which the sensitized and dried sheets of albumen paper were hung in a closed box and subjected to the vapors of ammonia. The ammonia fumes were supplied by placing strong ammonia in a dish in the bottom of the box. "Fuming" was usually carried on for 5 to 10 minutes. The purpose of fuming was to make the paper more sensitive and to obtain richer, more brilliant prints. While it is true that in some circumstances ammonia fuming will produce more sensitive and contrasty paper than would otherwise be obtained, nevertheless ammonia fuming is not necessary in order to produce good results.
Fig. 24. An advertisement for albumen paper, 1894. The tint of the paper and its quality level is shown on the label.
The confusion about the practice of fuming arises because ammonia fuming was a quite common practice in the United States and yet was hardly practiced at all in Europe;2' in Germany the practice was used very infrequently. Reading an American manual, one might find the fuming technique given a prominent place, while in a German manual it is only briefly mentioned. The resolution of this apparent contradiction lies in the fact that much of the value of fuming may be realized by simply increasing the strength of the silver bath or by aiming for negatives of slightly different density range. That is, other factors in the printing process may compensate for the lack of fuming and equally good results obtained.
The value of fuming was most important when a paper of low chloride content was sensitized on a relatively weak sensitizing bath. In this circumstance the extra sensitivity conferred by fuming might make a considerable difference in the results. However, with the use of a stronger silver bath only slightly more silver would be consumed, yet the paper would probably be as sensitive as the fumed sheet. In those places where the use of fuming had become customary, other factors in the process adjusted to that custom, and gradually fuming came to be perceived as a necessity; in areas where the practice never became customary, it was reserved for occasional use when extra sensitivity was called for. For the modern practice of albumen printing, the troublesome and unpleasant process of ammonia fuming seems unnecessary.
Albumen paper sensitized as described above will remain in good condition for 24 to 48 hours, depending on environmental conditions. For optimum results it should be both exposed and processed during that period. Care and patience should be exercised in every step of the printing operation, beginning with the loading of the printing frames. Make sure that the glass is clean and that the frame is working properly before risking a valuable negative. If a glass negative is used, a piece of foreign matter such as a splinter of wood between the glass of the frame and the negative can fracture the negative once pressure is applied. Always use felt pads in the printing frames to distribute the pressure, and make sure that the pads lie flat when re-closing the frames after checking the progress of exposure.
Fig. 25. Chickens and eggs were familiar motifs in albumen paper advertisements.
White light must be excluded from all operations in sensitizing and subsequent handling on :he paper, although it is helpful to evaluate the progress of exposure briefly with a low wattage white incandescent light. Yellow light does not allow the separation of tones in the middletone and shadow areas to be clearly seen, and under- or overexposed prints may be the result. The conduct of the printing operation itself is governed by the nature of the negative to be printed. A complete discussion of the factors involved in print exposure may be found in Chapter 7, but in general thin negatives are exposed to weaker and more attenuated light, while dense negatives may require the intensity of full sunlight. Only experience can provide the knowledge of how far to carry the exposure of any given print, but in all cases the print should appear too dark--to a greater or lesser degree--when leaving the printing frame. All prints bleach to a certain extent in the toning and fixing operations, but the exact degree of overprinting necessary will vary for different negatives and batches of paper, and also depends on taste. However, albumen prints require slightly less overprinting than salted paper prints do, and double-coated albumen papers need less overprinting than single-coated sheets.
The color of the prints after exposure will vary from a rich purple to a dark brown. The prints are very beautiful as they come from the frame, and many writers on the albumen printing process have remarked that they wished the prints could be preserved in that state forever. The exposed prints should be kept in a light-tight drawer or box until all prints are ready to be processed. The general outline of processing is the same as that given for plain salted papers at the end of Chapter 3. The first step in processing is an initial wash to remove the bulk of the free silver nitrate. Although the washing should be continued past the point where the wash water is free of the cloudy precipitate of silver chloride, do not allow the first wash to go on past 10 minutes in running water. Excessive washing removes the last small traces of silver nitrate that are necessary for some toners to work properly. The prints should be agitated or other steps taken to see that they are uniformly washed; they are now ready for toning.
The main difference between the processing of plain salted papers and that of albumen paper is the strength of the toning bath; albumen prints need a much stronger and more effective toning solution than salted papers do, because albumen is less permeable and the silver particles are more protected. This also means that the toning of albumen prints is usually slower--even with a stronger toning solution--than the toning of salted paper prints. Any variations in the thickness of the albumen coating, especially in the case of double-coated papers, will be immediately apparent in the toning step, because less heavily coated areas will tone more quickly and deeply.
Any of the gold toning baths given in Chapter 8 may be used with albumen paper. They should be used full strength for ordinary glossy albumen paper. A good way for beginning printers to get a sense of the toning process is to leave one print completely untoned, and fix it and dry it with the rest. In this manner a basis of comparison is established for the amount of toning that has taken place.
The historical practice of toning glossy albumen paper involved the used of gold toners almost exclusively, while salted papers and the later matte-albumen papers were toned with either gold or platinum toners or both used in combination. For glossy albumen paper, however, there can be little question of which toning method was usually applied, for all but a negligible few experimental prints were toned with gold toners of the kind described in Chapter 8. Black tones (instead of the usual cool browns and purples) were attainable with gold toners on albumen paper, but never gained great popularity.
The toning step is the focal point of the whole processing operation. Every other aspect of processing may be done "by rule" and is fairly routine, but toning of albumen prints is usually done by inspection. The problem with toning by inspection is that the prints alter dramatically in fixing and drying, and end up a little darker and colder in tone than they appear in the toning bath. Thus is it easy to under- or overestimate the amount of toning that has taken place. The progress of toning, even more so than the progress of exposure, cannot be accurately gauged in yellow light, so a weak white incandescent light is needed at intervals for evaluation of the toning operation. If the light is not too bright it may be left on during the whole toning process, because after the first wash the prints are considerably less sensitive. Another difficulty in toning is that all prints do not tone at the same rate, so that when one print in a batch is judged to be toned, the others in the same batch may not necessarily be toned to the same degree. The necessity of giving the prints individual attention limits the number of prints that may be toned at any one time.
The prints must be kept uniformly wetted and be constantly agitated during toning, or uneven toning will be the result. The gold toning solution should not be made too strong (in order to work more quickly), because too rapid a deposition of gold will spoil the prints. The gold layer will then be merely superficial, and will be largely removed in the fixing bath, leaving a flat and meager looking print. Also, if toning is carried to extremes in a normal strength bath, too much gold is substituted for silver and the prints turn an unpleasant slate blue color, and lose density. There must be a harmonious distribution of both gold and silver in the print to form an image of good color and contrast. Ideally the toning operation should last 10 to 15 minutes or even longer; in this way there is less chance of over-toning, and there is time to consider whether the prints are toned to the desired extent.
In large 19th-century galleries and mass-production printing establishments the toning of prints was a specialized occupation. The "tuners" in such places often used their own secret formulas, and each had his or her own special way of determining when a print was correctly toned. One thing to consider that may help in this determination is the extent to which the prints already have a purplish or cool brown color before the toning process is begun. Sometimes prints are quite reddish in color by the time they are ready to tone, and at other times the prints may retain the purplish color at that point. The purple color will completely disappear in the fixing solution, so if the purple color has fooled the "toner" into thinking that the toning has advanced farther than it actually has, then under-toned prints are sure to result. Many old manuals advise "redding up" the prints by. placing them in a 3% acetic acid solution for 10 minutes and washing them in running water before attempting to tone them. In the usual course of modern practice, "redding up" will not be necessary, because prints are usually not purplish at the point of toning unless ammonia fuming has been used.
In most cases the prints should take on a definite lilac or purplish tinge during toning, but the process should not be carried so far that the prints look at all bluish. The degree of toning to strive for is a matter of taste, but severe under-toning may lower the expected life-span of a print. The prints may be examined by transmitted light during toning to give a more accurate idea of how much toning has been accomplished. When by transmitted light the last traces of warm color have disappeared from the print, the toning process is quite advanced, and the final color of the print is likely to be purple or purplish-black. Many old manuals advise to tone until the warm color has almost disappeared by transmitted light. With each of the gold toning baths given in Chapter 8 there will be slight differences in rate of toning, and with the thiocyanate toner a difference in the mechanism of toning, but the general instructions given above apply no matter which toner formula is selected. When the toning is completed the prints should be given a running water wash for at least 5 minutes in accordance with the general outline of processing given at the end of Chapter 3.
Fixing of albumen prints is done in an alkaline 15% solution of sodium thiosulfate (also called "hypo"). While fixing the prints may appear to be a routine matter that does not require careful attention, in reality the permanence of the prints depends to a great extent on the observance of proper fixing procedure. The object of fixation is to render the image stable by removing any light-sensitive substances, leaving behind an image of metallic silver. As a practical matter, both fixation and washing of albumen prints is made more difficult by the nature of albumen itself, since coagulated albumen is resistant to penetration by solutions. Therefore attention to the correct procedure is of the utmost importance if thorough fixation of albumen prints is to be achieved. An explanation of the mechanisms of fixation and of the removal of harmful by-products of fixation will be found in Chapters 9 and 11.
Fig. 26. A novel print washer suggested in Photographic Mosaics for 1878.
The basic approach to fixing albumen prints is to use two fixing baths, both of which must be freshly made up the day on which they will be used. The prints should be uniformly wetted by the fixer and agitated constantly during the fixation process.
After 4 minutes in the first fixer they should be drained for at least 5 seconds and placed in a second tray of fresh fixer for an additional 4 minutes. The reason for the use of two-bath fixation is that some of the reaction products of silver chloride and sodium thiosulfate are insoluble in water and thus would never wash out of the print. The sulfur contained in these insoluble reaction products would eventually be released to attack and fade the silver image. However, these compounds--which are not soluble in water--are soluble in fresh sodium thiosulfate, and can be easily removed if there is a sufficient excess of fresh "hypo." This is the reason for the use of two fixing solutions.
It is important to make the fixing solutions slightly alkaline by adding 2 grams of sodium carbonate to each liter of fixing solution. This promotes more effective fixation and helps to prevent the blistering of the albumen layer on heavily albumenized papers. Another cause of blistering is too rapid changes in the temperature of processing solutions, so it is best to keep all solutions, including the fixer, at about 70°F (21 ° C). If blisters do appear, they do not spoil the prints in every case; if the blisters remain small they will sometimes disappear in drying, but if they are large or break, then the prints are usually ruined. Changes of temperature or pH of solutions are the main causes of blisters, but if they continually appear in spite of remedial measures, then there may be a problem of something in the rawstock reacting with the processing solutions. In that case a different rawstock will be needed.
When fixing is complete, the prints should be given a short wash (2 to 4 minutes) in running water and transferred to a hypo clearing agent solution at normal working strength. Either Kodak Hypo Clearing AgentTM or preferably, a 1% solution of sodium sulfite may be used for this purpose. After treatment in the hypo clearing agent the prints should receive a final wash for 30 minutes in an effective print washer. A large tray with a siphon arrangement will effectively wash one or two prints, but cannot satisfactorily handle more than that unless the prints are hand agitated during the entire washing period. To dry the prints a good approach is to gently blot them between acid-free blotters and allow them to air dry face up on fiberglass screens. Warm air may be used to accelerate drying.
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