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
|Sulphate of iron,||2 drachms.|
|Acetic acid,||2 drachms.|
|Nitrate of potassa,||½ drachm.|
|Nitrate of silver Solution,||30 drops.|
|Nitric acid,||12 drops.|
The image will gradually appear, and if the time of exposure has been right, you will be able to observe the three grades of contrast in the development, that is, dark parts or shades, middle tones, and lights. You will see, moreover, whether the relative conditions of the collodion and the silver-bath are in good working order, by the mode in which
the development takes place. If the whole surface of the collodion plate soon assumes a foggy, milky, or clouded appearance, with but faint contrast between the lights and shades, (and knowing that the camera is quite impermeable to light excepting through the lens,) you may fairly conclude one of two things, either that the time of exposure was too long, or the condition of the materials was not normally good. Of these difficulties I will speak shortly. By carefully watching the development it is not difficult to observe how the shades increase in density, how, in fine, the picture becomes more and more developed; and particularly the photographer can distinguish the regular shading of the background. At last the development arrives at its culminating point; if it were to proceed any further, the background and the transparent parts would begin to be foggy; the contrast diminishes, and finally the picture is spoiled. The rule is this: the moment the image is complete and the background has received its first shade, pour off the remaining part of the developer, and wash immediately and thoroughly by allowing a small stream of rain-water to play upon the surface until every trace of the iron is removed Wash also the posterior side of the glass in like manner. We now proceed to the sixth and last operation.
|Cyanide of potassium,||1 drachm.|
Have this solution ready. With the right hand place the collodionized plate in a gutta-percha dish held in the left hand, and pour upon the developed image a quantity of the above solution in a gentle stream, until all the white or yellow iodide of silver has been completely dissolved, taking care in the mean while that the fluid is kept moving backward and forward, so as to preserve uniformity of action. After this operation wash the plate again in many waters on both sides and until all traces of the cyanide are removed. Holding the positive now over a piece of black velvet in such a position by a window that the impingent rays shall reach the eye, the quality of the ambrotype can be determined. The picture must be quite clear; the shades dark, almost black; the lights brilliant and white; and in every respect the lines and points must be sharply defined. H there is no regular gradation of light into shade, bat almost one mass of shade, and the picture is offensively black, the time of exposure was too short or the development not carried on far enough; but if in this case the development had been continued until the retrograde action had set in, then certainly the time was too short. The remedy in such a case is quite natural; rub the picture out and take another with a longer exposure. If, on the contrary, the picture is hazy, or foggy as it is technically denominated, and the lights and shades too much blended or too little distinct from each other, and the development was rapid, and a difficulty presented itself in discriminating when the reduction began to assume a retrograde action, in such a case it may be confidently concluded that the time of exposure was too long. The remedy of course is known. But the defects just mentioned might have been caused by carrying on the development too long; and it would be very proper to attribute these defects to this cause, if the development had been slow and carelessly watched. But if the haze and fogginess commenced almost as soon as the developing solution was poured upon the surface, you would be justified in ascribing the cause of this veil over the picture to an abnormal condition of the silver-bath or the collodion. This evil indicates, as a general thing, alkalinity in either one or the other, or in both, and can be remedied by rendering either one or the other acid. it may be caused by a new bath and a new neutral silver solution.
If the collodion is nearly colorless and new, this material is probably the cause of the want of contrast in the picture, of the feebleness in the development, and, it is possible, of the veil that covers the whole plate. Take some highly colored old collodion and add it to the new in the proportion of one drachm in ten, and try another picture; or add to the collodion tincture of iodine, that is, a solution of iodine in alcohol. In either case, most likely, under the circumstances, an improvement will be manifest. If the picture is not yet perfectly clear, proceed in the same direction, that is, add more of the old collodion or of the tincture. If the bath is quite neutral or alkaline, it will be well indeed to drop in a minim or two of nitric acid. To do this take a drachm of distilled water and drop into it five minims of nitric acid. The mixture contains about sixty drops, of which six drops will contain about half a drop of nitric acid. Begin, therefore, and add six drops of the solution to the bath, and keep doing so until the picture is perfectly satisfactory. I prefer myself keeping the bath as nearly neutral as possible, and to apply the remedial action to the collodion, by adding free iodine or old collodion, of which the former seems by decomposition to liberate an acid in and on the collodion film in proper quantity, at the right time, and in the proper place; and the latter, that is, old collodion, effects the same result, because it has already undergone the decomposition of the pyroxyline that is called ripening, and contains the materials for producing intensity and for avoiding fogginess.
In taking collodion positives beginners are very apt to develop the plate too long, as well as frequently to expose in the camera too long. The right time in both instances can be attained only by practice, after having consulted the best instructions. As soon as the picture is distinctly visible by reflection, stop the development; if it is then faulty, the time was either too long or too short; too short, if the shades are altogether too black, and transparent by transmitted light, and vice versa, if the reverse.
Supposing the picture to be correct and satisfactory, we proceed next to the
which consists in drying the plate. The operation is performed by means of the large flame of an alcohol lamp, or by the radiating heat from a stove. holding the plate by the left-hand corner, between the finger and the thumb of the left hand, first allow all the water to drain off at the nearest right-hand corner, by inclining the plate for this purpose; then holding the lamp in the right hand, move the flame gently over the back of the plate, so as to avoid fracture, beginning at the top and proceeding from side to side, and gradually downward, until the film is thoroughly dried. A second inspection now, by viewing the picture, as before, on a dark background, and by reflected light, decides whether the positive is good, tolerable, or indifferent, because now the final colors of the shaded parts are attained. These shaded parts are of a bright, white silvery hue, with the developer above given. Some tastes are more gratified with a more subdued contrast in which the whites are more deadened. This can be effected by making use of a much more rapid developer, and by omitting the nitrate of silver, and the nitric acid. For this purpose the following formula will be found practicable.
Formula No. 2. For Collodion Positives.
|Sulphate of the protoxide of iron,||4 drachms.|
|Acetic acid,||6 drachms.|
|Nitrate of baryta,||2 drachms.|
Mix intimately, and filter before using. Prepare fresh every day.
The next step which the artist has to take consists in removing any particles that may have settled upon the surface of the picture, and in coloring the cheeks, hands, and drapery where required. Dry colors are used; those of Newman are regarded as the best. Very little color will produce an agreeable effect. With a fine sable or fitch pencil, take a small portion, and rub it gently on either cheek, on the lips, the hands, and forehead; then brush off the extraneous quantity, or shade the color off from the center of the cheeks, for instance, to the edges. On the lights of the drapery the requisite coloring may be laid on in like manner. This operation of coloring is frequently performed on the varnished surface. Finally with a large broad sable pencil remove all loose coloring particles, and now the positive is ready for the
Whilst the plate is still warm, uniformly warm from the drying operation, flow it with the purest and most transparent crystal varnish, precisely in the same manner as the plate was covered with collodion. The operation must be performed with dexterity and care; with dexterity in order to avoid all ridges caused by stoppage, and with care to avoid loss of varnish by escaping to the posterior part of the plate, upon the fingers, and upon the sides of the bottle, and the floor. The indurated varnish on the back of the positive may be removed by a tuft of cotton wool, dipped either in alcohol, benzole, or chloroform, according as the resins in the varnish are dissolved in either of these menstrua. Do not apply any heat from a large flame on the back of the plate before the varnish has dried, otherwise the ethereal fluid in which it is dissolved will take fire in many instances, arid spoil the varnished surface. When the film is somewhat dry and indurated, and not quite smooth, heat may be applied carefully, in order to remove the unevenness, or the want of brilliancy.
Varnishes for Collodion Pictures.
Formula No. 1.
|Pure benzole,||15 ounces.|
Dissolve and filter through Swedish or ordinary filtering paper.
Formula No. 2.
|White stick lac,||3 ounces.|
|Picked sandarac,||3 drachms.|
|Alcohol, spec. grav., 815,||40 ounces.|
|Oil of bergamot,||6 drops.|
Dissolve the resins in the alcohol by means of a water-bath, and filter. This varnish is immediately ready for use; and, like all varnishes, is the best when new.
Formula No. 3. Crystal Varnish. Soft Copal Varnish.
|Finely powdered Dammar resin,||5 ounces.|
Set aside in a closed vessel for a week, shaking the mixture from time to time for a day or two; then allow the insoluble gum to subside. Draw off the supernatant liquid, which, when clear, is ready for use. The collodion plate must be quite dry and cold when this varnish is applied, and the latter is allowed to dry spontaneously.
Formula No. 4. Amber Varnish, (with Chloroform.)
|Amber in fine powder,||3 ounces.|
Shake the mixture from time to time for eight or ten days, and then filter. This varnish, like the preceding, is poured, like collodion, upon the cold plate, but with great dexterity, because it dries very rapidly.
Formula No. 5. Amber Varnish, (with Benzole.)
Heat the amber first in a close vessel to a temperature of about 570° Fahr., when it begins to soften and swell, yielding white fumes. It is then dissolved in the benzoic. This varnish too is flowed upon the cold plate, and allowed to dry spontaneously. These two varnishes are more especially adapted for negatives.
If it should happen that a collodion picture becomes somewhat spoiled by the cracking of the varnish, it is recommended, if its restoration or preservation be of great importance, to take the following method. First ascertain whether the solvent of the varnish on the plate be alcohol, chloroform, or benzole, by dropping on one corner a minute drop of each of these menstrua, to ascertain which dissolves the varnish. Next take a tin box, somewhat larger than the picture, about one inch deep. At the bottom of this box solder a ring of tin, about half an inch wide, of the same shape, and nearly of the same size, as a support for the glass plate. Pour a small quantity of the solvent on the outside of the support; place the plate collodion-side upward on the ring; cover the box as nearly air-tight as possible with a piece of glass, and place it in a water bath. The vapor of the solvent will soon cause the varnish to swell, and the edges of the cracks to coalesce. As soon as this end in view is accomplished, the plate is carefully withdrawn, and, when cool, is again varnished with a similar varnish.
The plate having been varnished with a transparent resin varnish, we proceed finally to the last operation.
We have now to make a background for the positive, of some black material, which may consist of a piece of black velvet, black paper, etc., of the same size as the plate; or we may apply a coating of black varnish, either to the collodion surface, or to the posterior surface of the glass. If the varnish on the background be applied to the collodion side, the picture is not laterally inverted, but it loses considerably in transparency by, the intervening collodion; in consequence of this inconvenience, the background is generally placed on the side of the glass without the collodion.
Formula No. 1. For Black Varnish
|Oil of turpentine,||50 ounces.|
|Canada balsam,||4 ounces.|
Formula No. 2. For Black Varnish.
|Benzole or coal-tar naphtha,||50 ounces.|
Formula No. 3. For Black Tarnish.
|Pulverized bitumen,||10 ounces.|
|White wax,||2 ounces.|
Mix these ingredients together, and dissolve by a gentle beat; afterward filter and preserve in a well-corked bottle.
Varnish with bleached Shell-lac.
|Freshly bleached shell-lac,||4 ounces.|
|Canada balsam,||2 drachms.|
Dissolve at a warm temperature; allow to settle, and decant the clear portion for use.
The following varnish is used on the cold plate, is very hard when dry, and is not softened at a high temperature when printing.
|Gum sandarac,||4 ounces.|
|Oil of lavender,||3 ounces.|
Digest, dissolve, and decant as usual.
The positive print, denominated an ambrotype, is now finished. It remains only to fix it in a case or frame. In the first place a piece of very transparent and unblemished glass, of the same size as the type, is thoroughly cleaned, and its edges filed, as for collodion purposes, and all particles are brushed from its surface. It is then placed in a Preserver; over this comes a Mat; next the Ambrotype. The two latter are then firmly folded within the flexible edges of the preserver, and the compact mass is finally adjusted in its appropriate case.
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