Bleaching Solution.—Make a saturated solution of muriate of ammonia (sal ammoniac) in pure water, and filter through paper. Reduce with an equal quantity of water when used. When the linen or any other portion of the impression is badly solarized, after removing the coating, rinse with water; then pour this upon the surface in the same manner as the gilding solution. If the solarization be very deep, apply the lamp beneath, and warm the plate a trifle. Now pour off, and, without rinsing, apply the gilding. The whole operation must be quickly performed, or the chlorine soon attacks the shades of the picture. When properly done, however, the solarized parts are restored to a clear, transparent white.
Electro, or Cold Gilding.—This process I have adopted, and it produces exceedingly beautiful impressions for the stereoscope, adding a great charm to the pleasing effect of that instrument. It also possesses a pretty and curious effect on views. It is easy of trial, and may be used by dissolving one gramme of chloride of gold in half a litre of ordinary water, and thirty grammes of hyposulphite of soda in another half litre of similar water; then pour the solution of chloride of gold into that of soda, by little and little, agitating it exactly as in M. Fizeau’s preparation, of which there is but a variation.
When you wish to use it, pour some into a plate, or any other vessel of the same kind, sufficient to cover the proof; then, after having added to it a drop of ammonia, immerse the plate in it as soon as you take it out of the mercury-box, after having wiped its back and edges, and agitate the mixture quickly from right to left, so as to dissolve rapidly the coating of iodide of silver as usual. As soon as the plate appears white, cease all rapid motion, but continue to give it a slight undulating one; for if it were allowed to remain still for only a few minutes, the proof would be clouded. By little and little, the surface of the plate takes a yellow tint, which darkens more and more, approaching to bistre. You stop therefore, at the color you wish; and when the proof has been washed and dried, in the manner previously explained, it will be found to be fixed, without any stain, with a limpid surface, and an extraordinary warm tone. If you were to augment the proportions of the ammonia or chloride of gold, the operation would progress much quicker, but then the middle of the proof would be always much clearer than towards the border. The mixture may be used several times without being renewed. It does not, however, give such a beautiful color to the impression as when it is newly prepared. By communicating to the vessel containing the solution a continual motion, the impression, when once immersed, will be fixed. During that time, and while attending to anything else, watch its color; and at the end of ten minutes or a quarter of an hour, take it out of the bath and dry it.
Agent for Neutralizing Bromine, Chlorine, and Iodine Vapors.—Aqua ammonia, sprinkled about the chemical or coating room, will soon neutralize all the vapor in the atmosphere of either chlorine, bromine, or iodine. No operator should be without, at least, a six-ounce bottle filled with ammonia. A little of its vapor about the camera-box has a decided and happy effect. Burnt coffee, pulverized, has also the property of destroying the vapors of the above chemicals, as also almost any other agent employed about the Daguerreotype room. Its deodorizing properties are such that if brought in contact with air filled with the odor of decomposing meat, it will instantly destroy all disagreeable smell. It can easily be used in the Daguerreotype room by placing a little of the raw bean, finely pulverized, on an old plate, and roasting it over the spirit-lamp.
Buff Dryer.—There are various methods for keeping buffs dry and free from dust. Some place a sheet of iron against the wall at an angle sufficient to put a lamp between it and the wall, and then let the buff rest against the top of the sheet. By this method the buff is for its full length close to the heated iron, and at the same time exposed to the heated atmosphere and any dust that may be free. I would recommend some arrangement by which the buff would be inclosed. I have found the following to answer the purpose well, which is a box of sheet iron twenty inches long, eight wide and five high, with one end left open and the other closed; the cover is made of the same material, with the edges bent over to go on and off. There are several wires running through the centre of the sides, which it is necessary to cover with cloth or paper to absorb all the moisture that may be made by applying the heat, and the buffs are put in and taken out at the open end. In order that the heat may be as nearly uniform as possible, an iron bar one inch wide, eighteen inches long and one half inch thick, is so bent that the centre is one quarter inch from the bottom of the box, and that at least two inches of each end come in contact with the bottom; this being riveted on the bottom, and a lamp with a small blaze applied to the centre of the bar of iron. This will constitute one of the best and cheapest buff dryers in use. It may be suspended from the wall by placing wires around it, or it may stand upon legs. Perhaps a more convenient plan is to place it under the workbench in a similar position to a drawer. One precaution is necessary: when first heating the dryer, apply but a very gentle heat. This will prevent an accumulation of moisture, which would otherwise pass off in steam, coming in contact with the buff, thus causing a dampness. Another caution: never have the temperature of the air in the heater more than ten degrees above that which surrounds it.
When wheels are used, they should be encased in a sheet iron or wood case. All those made for our market are provided in this respect.
Keeping Buffs in Order.—This is one of the most important objects to arrest the attention of the operator. Every buff is more or less liable to get out of order by dust falling upon or coming in contact with the polishing powder employed in cleaning the plate. The edge of every plate should be thoroughly wiped and freed from any material that may adhere while cleaning. I have adopted the following method, which proves highly successful:
Rub the buff leather, holding the face down, with the sharp edge of a pair of shears or a piece of glass. This brings out any portion of the skin which may have become matted from any moisture, and also takes out any substance imbedded in it, and prevents it from scratching. Then, with a stiff brush, rub the buff well, and it will be found to work well. This same process employ on wheels and hand buffs every morning, or oftener, as occasion requires.
Preparing Buffs.—Two of these are necessary. That part of the stick to be covered should be about eighteen or twenty inches long, and three wide, and made crowning on the face from one end to the other, about one half inch. Before covering, these are to be padded with two or three thicknesses of Canton flannel. The buff should not be too hard, but padded with flannel, so that by drawing it over the plate, it may touch across the surface. The only proper material for buffs is prepared buckskin; and if prepared in a proper manner, this needs nothing but to be tacked upon the stick. There are several varieties of wheels employed; the one most generally adopted is Lewis’ patent, which consists of several varieties of wheels. Any operator can make a suitable wheel on the same plan of a turning lathe.
To Clean Buckskins.—When the operator is compelled to purchase an unprepared buckskin, the following is a good process for cleaning it: There is always in the buckskin leather that is purchased, more or less of an oily matter, which is acquired in its preparation, sometimes even amounting, to a third of its weight. The following is the mode of ridding it of this noxious ingredient: Dissolve, in about six or seven quarts of filtered water, about five ounces of potash; when dissolved, wash with the solution an ordinary buckskin; when it has been well stirred in the liquid, the water becomes very soapy, owing to the combination of the potash with the oily matters contained in the skin. Throw away this solution and use some fresh water without potash and rather tepid; change it several times until it remains quite limpid. Then gently stretch the skin to dry in an airy shaded place. When thoroughly dried, rub it well between the hands. It thus becomes very pliant and velvet-like.