Towler, John. The Silver Sunbeam. Joseph H. Ladd, New York: 1864. Electronic edition prepared from facsimile edition of Morgan and Morgan, Inc., Hastings-on-Hudson, New York. Second printing, Feb. 1974. ISBN 871000-005-9
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THESE comprehend the Talbotype or Calotype, and the Wax-Paper Process of Legray, and its modifications.
This process is a negative on paper. Talbot. published, six months before the discovery of the Daguerreotype, his process with the chloride of silver; and the year following the Calotype, or, as it is now frequently denominated, the Talbotype, was made known. The object is to obtain a depositor film of iodide of silver of a fine and even structure upon the surface of paper. The best paper for this purpose is of the English manufacture, being sized with gelatine, the foreign papers being sized with starch.
There are two methods of iodizing
1st. Float the papers on a solution of iodide of potassium, and allow them to dry; afterward float them on a solution of nitrate of silver. By double decomposition, a film of iodide of silver is formed on the surface in contact with nitrate of potassa..
2d. Add a solution of iodide of potassium to one of nitrate of silver. Collect the yellow precipitate, and dissolve it in a strong solution of iodide of potassium. The paper is floated for a moment upon this solution and dried. It is then floated upon water which decomposes the salt, and precipitates the iodide of silver in a very finely divided state on the surface of the paper. The sheets of paper are then dried. Their color is a pale yellow, and they are as yet not sensitive to light.
Float the papers, or rather brush over their surfaces a solution of nitrate of silver, containing both acetic acid and gallic acid. Acetic acid acts here as elsewhere: it diminishes the energy of the decomposition; it preserves the whites of the paper.
The Talbotype process in more definite terms stands as follows:
Float the paper in the following solution for a minute
|Nitrate of silver,||60 grains.|
|Distilled water,||2 ounces.|
Hang up the paper in a dark room to dry. Next float it in
|Iodide of potassium,||1 drachm.|
|Distilled water,||2½ ounces.|
for ten minutes; afterward it is soaked in water for an hour, in order to remove the excess of iodide, and then dried. It is sensitized by brushing over it the following solution
|Nitrate of silver,||25 grains.|
|Distilled water,||4 drachms.|
|Glacial acetic acid,||1 ounce.|
|Saturated solution of gallic acid,||1½ ounces.|
In a few seconds the excess is allowed to flow off, and, after draining, it is placed between folds of blotting paper, when it is ready for immediate use. If the sensitized paper has to be kept some time, a much weaker solution of gallo-aceto-nitrate is used than that just prescribed. To every ounce of the above solution add from thirty to fifty ounces of distilled water, according to the temperature of the climate and the time it has to be kept.
An exposure of the paper in the camera whilst still moist for a second or two will produce a latent image, which is developed in full intensity by washing the paper with a mixture of four parts of the saturated solution of gallic acid, and one part of a solution of nitrate of silver, (50 grains to the ounce of water.) The image soon begins to appear, and is fully developed in a few minutes.
Immerse the prints in a solution of bromide of potassium of ten grains to the ounce, or in one of hyposulphite of soda, as was afterward indicated by Sir John Herschel, of one part of the salt to ten parts of water, until the yellow iodide has been completely removed. The prints are finally washed in many waters, dried and saturated with white wax, which renders them transparent.
Several distinguished photographers have improved upon this calotype process, amongst whom we may mention Blanquart-Evrard, Legray, Baldus, Geoffray, Tillard etc. Amongst all these improvements and extensions the wax-paper process of Legray is the most extensively employed. For tourists it presents undeniable advantages in portability of material, and less liability to fracture. The wax, too, is a decided preservation of organic matter against the action of nitrate of silver.
This is the simplest of all the processes for taking negatives on paper. It differs from the calotype, inasmuch as the paper is first waxed before sensitization in Legray's process, whereas in Talbot's the waxing part of the operation is the last. The paper suitable for this process must be thin, compact, homogeneous, when viewed by transmitted light, and the sizing of the paper must have been carefully performed. The English papers, although perhaps the finest, are not suitable, from the fact that they have been sized with gelatine, which presents great difficulty in the waxing. Saxony negative paper is considered the best.
Obtain pure white wax from the bleacher's, or, in case this can not be procured, make use of the purest yellow wax that can be had. Next prepare a water-bath in which water can be kept boiling, either by lamps or a charcoal-fire. On the lid of the water bath place a porcelain or metallic plate, and when hot, rub the surface with the wax until it is covered uniformly with a layer of melted wax. Place upon this a piece of paper to be waxed. Rub its surface in like manner, until it is uniformly covered and transparent; and proceed in this manner until a pile of eight or ten papers is thus formed. If the dish is sufficiently large, place a piece of paper by the side of the pile, and then if the uppermost paper on the pile is quite transparent with wax, place it upon the dry paper; upon this place another sheet of unwaxed paper, and then on this the second one from the pile, and proceed thus until all the waxed papers are interleaved with dry sheets. The intention of this operation is to get rid of the excess of wax. Repeat this operation until the object is effected. Use a pad of cotton, and gentle pressure on the top of the pile as you proceed, but be very careful not to make a single crease, otherwise the sheet in question is utterly spoiled. As soon as the paper ceases to shine from the melted wax, it is time to stop any further removal of wax. The sheets of paper, that have served as interleaves, maybe used in the preparation of the next batch of waxed papers. The papers thus prepared are separated, and when the wax has congealed in their fibrous structure, they are put away for future use between plates of clean glass.
Formula of Legray.
|Sugar of mills,||1 ounce.|
|Iodide of potassium or ammonium,||3 drachms|
|Bromide of potassium,||48 grains.|
* Take seven ounces of rice and bruise it; then boil it in seven pints of rain or distilled water. As soon as the rice yields beneath the fingers, the boiling has been carried on far enough. The water is decanted, and to this are added forty-six grains of isinglass to each pint of rice-water, and the mixture is again boiled.
Mix, dissolve, and filter. It is necessary to be supplied with an abundance of this bath, in order that the papers can easily be submerged, in which there is considerable difficulty by reason of the fatty nature of wax. This bath can be preserved a long time if kept, after using, in well-stoppered bottles.
When about to use this bath, pour it into one of the deep dishes employed in other operations in photography, such as for albumenizing or for toning, and let it be two or three inches in depth when poured in.
Take each paper by two opposite diagonal corners, and bending it into a hollow curve, immerse first one of the two other diagonal corners, and than the other; move the paper backward and forward, so as to get the fluid over it, gradually lowering the two corners held in the hands. Finally, by means of a glass triangle or bent glass rods, press the sheet entirely beneath the surface of the liquid, and remove all bubbles. Proceed in like manner with all the rest, carefully avoiding all bubbles between the papers. In about two hours the papers will be sufficiently impregnated with the iodizing solution; after which they are taken out singly by first raising one corner with a glass rod, and then seizing this with the left hand, it is removed from the liquid and allowed to drain for a moment, and finally hung upon varnished hooks to dry; or the papers maybe suspended on a line by clamping each upper corner by means of a clothes-pin. Great care is required so as not to produce any wrinkle or crease in the papers in any of these operations. Several iodizing solutions have been proposed; the following with whey or serum is found to work well.
|Whey* or serum,||25 ounces.|
|Sugar of milk,**||4 drachms.|
|Iodide of potassium,||3 drachms.|
|Bromide of potassium,||48 grains.|
* Whey is obtained by boiling a couple of quarts of skimmed milk, and then adding, as soon alit begins to rise, acetic acid drop by drop until the curdling or coagulation is complete. The whole is then poured into a muslin bag and filtered. When it has cooled down to about 100° or blood beat, the white of an egg well beaten is added and stirred up. The liquid is again made to boil, and by the coagulation of the albumen, the whey becomes clarified. It is filtered a second time, and is then ready for use.
** Sugar of milk is concentrated whey, or that part which crystallizes when whey is evaporated to a syrupy consistence. This sugar of milk, or lactin, as it is also called, is purified by animal charcoal and again crystallized. It forms white, translucent, four-sided prisms of great hardness. It is soluble in five or six times its weight of cold water; its taste is feebly sweet, and feels gritty between the teeth. It enters into combination with the protoxide of lead, and is converted into grape sugar by boiling with dilute mineral acids. It can be made to ferment, but does not do so spontaneously.
To the first of the two preceding formulas, containing rice-water, which is that of Legray, the author of the process was in the habit of adding a small quantity of the cyanide and fluoride of potassium, which are regarded now as of little or no consequence.
When removed from the iodizing bath, the papers have changed their appearance; they are now in a spongy condition and devoid of transparence; but by heat they may be restored to their original state. They frequently assume a violet color. When dry, the sheets of paper are placed one over the other, between pieces of blotting-paper, and packed in a well-closed card-board box for future use.
The alkaline iodide in the waxed paper is converted into iodide of silver by immersing the sheets in the following aceto-nitrate of silver bath
|Re-crystallized or pure nitrate of silver,||7 drachms.|
|Glacial acetic acid,||7 drachms.|
|Distilled water,||12 ounces.|
Filter the bath into the appropriate dish and sensitize one sheet at a time, or at least do not place one sheet over another, and take care to break up all bubbles on the surface of the wax-paper. After remaining two or three minutes in this bath, each sheet is taken out, immersed in a dish of rain-water, well washed, and then immersed in a second. Afterward it is taken out, allowed to drain, pressed between folds of bibulous paper until it is no longer wet, but simply moist. In this condition it may be placed between two pieces of clean glass and exposed immediately, or it may be gummed along the edges, and then pasted upon a sheet of card-board and dried for future use.
De Champlouis has introduced an improvement into this part of the process. As soon as the sheets are removed from the aceto-nitrate bath, each is placed whilst still moist on the glass destined to receive it in the plate-holder; it is then carefully pressed on the surface by means of a small piece of sponge, in order to expel any bubble of air which, by remaining between the paper and the glass, might produce uneven reductions. On the sensitized paper a sheet of blotting-paper is in like manner applied by the sponge, and afterward a sheet of wax-paper or wax-cloth, which subserves the purpose of a final pressure. These two sheets must be thoroughly moistened with distilled water; they form a sort of cushion, which is pressed together by a second glass of the same dimensions as the first. The whole arrangement may then be placed in the plate-holder, for it is ready to receive the view immediately, or at any time within twelve days. By this expedient the paper dries very slowly from the edges to within. No washing is required before exposure, which is a great saving of time.
Iodized wax-paper, whatever may be its color before, whether yellow, reddish, or violet, is very quickly bleached in the silver bath.
The sensitized sheets, however prepared, must be protected against all access of light, otherwise they will be utterly spoiled. There are changing-boxes to be had for the reception of waxed paper sheets as also for dry plates; these are so arranged as to contain a certain number of sheets or plates, and to expose one at a time without any injury to the rest: Without such an arrangement, the tourist will be obliged either to have as many plate-holders as plates, or to have a small dark-chamber in which the hands can make the requisite changes by feel. The time of exposure of course is variable, according to temperature and the brilliancy of the light. Two or three minutes in a good light will in general be sufficient; in ordinary light on an average from ten to fifteen minutes will be required.
This operation may be performed right away or any time within twenty-four hours. In extreme cases the development may be postponed for a week; but the best results are obtained by developing immediately after exposure. The image, as a general thing, is not visible when taken from the plate-holder; excepting, perhaps, in parts especially where the paper has been well washed. The most constant developer is that of Crookes.
Heat in a glass flask twenty fluid ounces of concentrated alcohol to near the boiling point, and then add four ounces and a half of gallic acid; filter this solution into another vessel containing seventy-two grains of glacial acetic acid. This forms the stock solution of gallic acid which will keep for an indefinite time. It has a brownish color, but it is clear.
When about to develop a picture, measure out two fluid ounces of rain-water, to this add half a drachm of the alcoholic solution of gallic acid and seven minims of a solution of nitrate of silver containing eighty-six grains to the ounce of water.
The sheets of paper are kept submerged in this bath for about half an hour, by means of the glass rod or triangle, when the development will be complete, which must be determined by experience.
De Champlouis develops as follows
In the first place the paper is previously passed through the silver bath, in order to restore its humidity, if it is already dry; it is next placed on a plate of window-glass and floated with a thin layer of gallic acid solution; the image appears with great rapidity, owing to the quantity of silver in the moistened paper; notwithstanding this, the operator can easily follow the development. By pursuing this plan, spots and other mishaps are avoided.
Whichever plan is pursued, the temperature must always be at about 80°; the developing solutions can be used only once, and are then accumulated and reduced. Whilst the paper is developing, a dirty deposit appears gradually to cover its surface; it need not, however, cause any anxiety. The surface, too, becomes spongy and porous after development--a condition which is removed afterward.
If the exposure has been too short, the image is very slow in appearing, unless an excess of aceto-nitrate of silver be used, and even then there is a want of vigor, and especially of the middle tones. Such a negative will produce only blacks and whites in the positives printed from it.
If, on the contrary, the time has been too long, the surface presents a red tint, and the development commences with great rapidity on every part simultaneously, and soon assumes a uniform shade which takes away all contrast. For this there is no remedy; so that a short exposure is preferable, because a certain degree of vigor in the latter case, as well as contrast, can in general be obtained. The development is to be observed, as it progresses, by transmitted light, otherwise you might be deceived by the gray deposit already alluded to, and think the negative spoiled.
If the time has been about right, the print will appear possessed of the right gradations of light and shade, and of proper density of shade. As soon as the darkest parts are so opaque as to prevent an object from being distinguished through them, the development maybe considered complete. All further action is then stopped by immersing the negatives in water and washing it well by agitation, or by placing it on a plate of glass and then washing it from the tap, first on one side and then on the other.
This is effected by allowing the paper to remain for a quarter to half an hour in a solution of
|Hyposulphite of soda,||2 ounces.|
or until all the yellow color on the white parts has disappeared. The print is then well washed as before, and finally left in a vessel of water for a number of hours. Finally it is taken out, allowed to drain, and dried between folds of' blotting-paper.
When dry the papers have lost their brilliancy, they have a spongy appearance, and as if covered with an infinite number of small protuberances, such as are caused by the iodizing solution. The brilliancy can be restored and the spongy appearance be removed by holding the papers over a fire, or by placing each between sheets of blotting-paper on a water-bath, or finally by running a hot iron over each, so protected with bibulous paper. The iron, however, must not be hotter than boiling water. The wax-paper negatives are now complete, and are ready for use; from them positives on paper are obtained as from glass negatives. When not in use, they are preserved in a portfolio.
The author separates the cerolein from the myricin and cerin of bees-wax as follows:
Dissolve five ounces of yellow or white wax in ten ounces of alcohol in a retort, by means of heat raised to the boiling temperature; receive the distillate in a cool receiver, until the wax is completely dissolved. The melted wax is then poured into a vessel to cool; gradually the myricin and cerin solidify, and the cerolein remains alone in solution with the alcohol, which is separated by pouring it upon a fine muslin sieve, and finally being mixed with the distillate, it is filtered through paper. This forms the stock solution of cerolein No. 1.
Secondly, dissolve in three drachms of alcohol (spec. grav., .849) four drachms of iodide of ammonium, (or of potassium,) twelve grains of bromide, either of ammonium or of potassium, and twelve grains either of fluoride of ammonium or of potassium.
To twelve grains of freshly prepared iodide of silver add drop by drop of a concentrated solution of cyanide of potassium, until the former is dissolved, and then mix this with the alcoholic solution of the iodides, etc. There will be a deposit of salts undissolved in this mixture, which is bottle No. 2.
Of these two solutions the author takes, when about to use, about twenty drachms of No. 1 and two drachms of No. 2, and filters into a porcelain dish. This forms the bath in which the papers are immersed for about a quarter of an hour, five or six at a time, until the solution is exhausted. The papers when dry have a rosy tinge. The operations of sensitizing, etc.., are the same as in Legray's process.
White wax, in small pieces, is digested in the essence of turpentine for several days; the solution is then decanted and filtered. To every three ounces of this solution add seven grains of iodine, which is immediately dissolved without discoloration, or if any be produced, expose the mixture to the sun. Now add about from forty to forty-five drops of castor oil, pure and freshly made, to the above quantity of wax and turpentine. This forms the bath when filtered, in which the papers have to be immersed for five minutes or so. They are then sensitized, when dry, in the following bath
|Nitrate of silver,||1 drachm.|
|Nitrate of zinc,||2½ drachms.|
|Acetic acid,||2½ drachms.|
The paper is then washed carefully and dried. After exposure, the prints are developed by immersing them in
|Distilled water,||5 ounces.|
|Saturated solution of gallic acid,||5 ounces|
|Acetic acid,||1 ounce.|
To which is added a small quantity of a fresh solution of nitrate of silver. This process is said to be very rapid.
As before mentioned, various improvements have been made in the calotype and wax-paper processes, amongst which I shall finally give the wet-paper negative process of Humbert de Molard, owing to its simplicity and the rapidity of its action.
The papers are floated for five minutes on the following solution
|Distilled or rain-water,||6 ounces.|
|Iodide of ammonium,||2 drachms.|
They are then taken out, hung up, and dried. This paper will not keep long, and must not, therefore, be prepared long beforehand. With most papers, that is, those which are sized with starch, a violet color is produced by this floating, owing to the free iodine generally existing in iodide of ammonium.
When dry and about to be used, float each sheet on the following bath
|Distilled or rain-water,||6 ounces.|
|Nitrate of silver,||3½ drachms.|
|Nitrate of zinc,||1½ drachms.|
|Acetic acid,||1½ drachms.|
It is then placed with its, moist side downward on a clean piece of glass and exposed to the object, taking care to make allowance for the thickness of the glass. From three to thirty seconds will produce the required result. The paper is next floated on the developer, which consists of
|Water saturated with gallic acid,||6 ounces.|
|Water saturated with acetate of ammonia,||from 48 to 60 drops.|
The image appears with great rapidity, and its development has to be carefully watched. The washing and fixing are performed as usual. When dry, the negative prints are waxed, in order to give them the requisite transparence for the printing operation.
Take a sheet of iodized Turner's paper, half an inch wider and longer than a plate of glass fitting in the dark slide for the dry collodion process; pin it on to a board in the usual way, and, with a glass rod, spread over the paper a solution composed of
|Nitrate of silver,||28 grains.|
|Distilled water,||1 ounce.|
|Glacial acetic acid,||10 drops.|
Allow this to remain on the paper one minute, and then, carefully and evenly, pour one ounce of water over the paper, which is easily done by holding the board on which it is pinned slantingly, and take care that the lower edge of the paper reaches just beyond the corresponding edge of the board. Repeat this washing a second and a third time, and then pin up the paper to dry, or it may be dried between folds of blotting-paper. Now turn the sensitized surface downward on a sheet of white blotting-paper, and placing the plate of glass upon the non-sensitized side, with a little thick gum attach the overlapped edges of the paper to it. If the paper lies even-and it will do so if, when slightly moist, it be gummed to the glass, and afterward dried-it may then be exposed for a few minutes to the view. The time, of course, has to be learned by experience for given intensities of the light and the power of the lens.
After it has been exposed, separate the paper from the glass with a penknife, and develop the picture with a solution of gallic acid, to which has been added two drops of the silver solution to each drachm of the gallic acid solution. The picture comes out very quickly, and when it is fairly out, the development is completed with the gallic acid solution alone.
Fix with a weak solution of hyposulphite of soda; wash, dry, and wax by means of a hot iron, white wax, and blotting-paper.
The points requiring most care are:
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