Manipulations.

Under the head of manipulations I give the method I employ, and avoid confusion by omitting all comments upon the thousand suggestions of others.

The glass is to have its sharp edges and corners removed, by drawing a file once or twice over it. The article used for holding the glass is called a vice. This vice is firmly secured to a bench.

[Since the foregoing pages have been in type there has been introduced into market a new patent vice, adopted both for glass and plate blocks. I find it, although a little more expensive, an article better suited to the wants of the operator or amateur. It is called Lewis's Patent Glass Vice.]

Clasp the glass firmly in the vice, and pour or spurt upon it a little alcohol and rotten stone, previously formed into a paste, and then, with a piece of cotton flannel, the same as used in the daguerreotype, rub the glass until it is perfectly cleansed from all foreign substances, which will soon be known by experience. The rotten stone paste should not be allowed to dry while rubbing, as it is more liable to scratch the glass. I use another small bottle containing clear alcohol, which I spurt upon the glass, to obviate the drying.

When the glass has been sufficiently cleaned, it should, while wet, be put in a vessel of water for future rinsing. Clean, as before, as many plates of glass as may be required, and when enough are ready, rinse them off in the water, and then in a quantity of clean water, or a running current, give them a second thorough rinsing, and set them aside to drain.

A convenient method of doing this, is to drive two nails horizontally into the wall or partition, a sufficient distance apart (say about 2½ inches) for the glass to rest on: the upper corner of the glass should be placed against the wall, and the extreme lower diagonal corner left hanging between the nails—which will probably be found the best position for draining yet suggested.

After drying, they may be put into a box for safe and clean keeping. Particular caution is necessary to avoid handling the glass during the operation. I never take the glass between my fingers, so that they come in contact with both sides of it, except at one particular corner, as at Figs. A and B. A quantity of glass prepared as above, may be kept on hand for use two or three days, and when wanted they should be again put into the vice[C] and cleaned, first with cotton flannel wet with alcohol, and then with dry flannel; and then, at a temperature slightly above that of the surrounding atmosphere, except in cases where the thermometer stands above 70°, it is ready for the brush,[D] which should be carefully applied to each surface, to free it from all particles of dust, and then it is ready for the film of collodion.

The glass is held between the thumb and forefinger of the left hand by the corner 1, Fig. A., 3 and 4 towards and nearest the body, and as nearly level as possible. I find this the best position to hold the glass; as, in the case of the larger ones, they can be rested on the end of the little finger, which should be placed as near the edge as possible. Then, from the collodion vial, pour on the collodion, commencing a little beyond the centre and towards 1, continuing pouring in the same place until the collodion nearly reaches the thumb—the glass slightly inclined that way; then let the glass incline towards 4, and continue to pour towards 2.

As soon as enough has been put on to liberally flow the glass, rapidly and steadily raise corner 1, and hold it directly over 3, where the excess will flow oil into the mouth of the vial, which should be placed there to receive it. In case of a speck of dust falling at the time of coating, it can often be prevented from injuring the surface by changing the direction of the flowing collodion, so as to stop it in some place where it will not be seen when the picture is finished. Now, with the thumb and finger of the right hand, I wipe off any drops or lines of collodion that may be found upon the outer edge or side of the glass, being careful not to disturb that connected with the face.

When the coating has become sufficiently dry, so that when I put my finger against it, it does not break the film, but only leaves a print, I put it into the silvering bath [see Fig. p. 34]. I generally try corners 2 and 3. The time, from the first commencement of pouring on collodion to its being put into the bath, should not exceed about half a minute, at a temperature of 60°. The finger test is the best I have found. The glass is to be rested on a dipper [see Fig. p. 34], and placed steadily and firmly into the nitrate of silver bath—this in a dark room. It should not be allowed to rest for an instant as it is entering the solution, or it would cause a line. The time for the glass to remain in the bath depends upon the age and amount of silver the bath contains; for a new solution, from two to three minutes will be sufficient to give the proper action. If it be old, three to five minutes will be better. When it is properly coated, it can be raised up and taken by the corner, and allowed to drain for a few seconds, and then should be placed in the tablet, and is ready for the camera. The time of exposure will depend upon the amount of light present. If the bath is newly mixed, and the collodion recently iodized, it should produce a sufficiently strong impression by an exposure of about one-third of the time required for a daguerreotype. If the collodion has been iodized some time, and the bath is old, about one-half of the time necessary to produce a daguerreian image will be required.

The plate should in no case be allowed to become dry from the time it is taken from the bath up to the time of pouring on the developer. At a temperature of about 70°, I have had the glass out of the bath ten minutes without drying. After exposure, the glass should be taken again into the dark room, and removed from the tablet and held over a sink, pail, or basin and the developing solution poured on it as follows: hold the glass between the thumb and finger of the left hand, by the opposite end corner from that in coating with collodion, i. e., 2, and let 3 and 4 be from you.

Commence pouring on the developing solution at the end by the thumb, and let it flow quickly and evenly over the entire surface, the first flooding washing off any excess of nitrate of silver there may be about the edges or corners of the glass (if this silver is not washed off, it flows over the edges and on the surface of the impression, producing white wavy clouds of scum), and then hold the glass as nearly level as possible, it having upon its surface a thin covering of solution (care should be observed not to pour the developing solution on the plate in one place, as it would remove all the nitrate of silver and prevent the development of the image, leaving only a dark or black spot where it is poured on). Put down the bottle containing the developing solution, and take up a quart pitcher previously filled with water, and as soon as the outline of the image can be plainly seen by the weak or subdued light of an oil or fluid lamp or candle, pour the water over copiously and rapidly. Continue this until all the iron solution has been removed. If this is not done, the plate will be covered with blue scum on the application of the washing solution. Then the glass can be taken into a light room, and the iodide of silver coating washed off with the cyanide solution, and then rinsed with clear pure water, and stood in a position to drain and dry. I place a little blotting paper under them: it aids in absorbing the water, and facilitates the operation.

Place the face of the glass against the wall, in order to prevent dust from falling upon it. I have often dried the coating by holding or standing the glass adjacent to a stove. A steady heat is advisable, as it leaves the surface in a more perfect state, and free from any scum. After the coating is perfectly dry, it is ready for the preserving process. It should be warmed evenly, and when about milk warm, "Humphrey's Collodion Gilding" is poured on the image in precisely the same manner as the collodion. In a few seconds the coating sets, and after three-quarters of a minute, if it has not become dry, the blaze of a spirit lamp may be applied to the back and it will immediately become perfectly transparent, and nearly as hard as the glass itself: the effect is fully equal, if not superior, to that of chloride of gold in gilding the daguerreotype image. The surface becomes brilliant and permanent. The back of the glass can now be wiped and cleaned with paper or cloth, and gently warmed, and then with a common small brush one coat of black varnish can be applied. This brush should be drawn from side to side across the glass, and on the side opposite to that which has received the image.

This is in order not to make streaks in the coating of varnish, but to have uniform lines across the entire length or breadth of the glass. If the varnish is of the proper consistency, it will flow into a smooth, even coating. After this first coating is dry, apply a second in the same manner, only in an opposite direction, so as to cross the lines of the first, uniting at right angles; when this last coating is very nearly dry, a piece of paper, glazed black on one side, and cut to the proper size, can be put next the varnish; it gives it a clean finish, at the same time that it aids towards a dense blackening.

I sometimes apply the black varnish by flowing, in the same manner as in putting on the collodion.

This picture is to be colored and put up in the same manner as the daguerreotype image, with a mat and glass. The last glass may be dispensed with by first using the collodion gilding, and then upon its surface apply the black varnish, as before. In this case the image is seen through the same glass it is on, and without being reversed: in this case the mat goes on the outside of the glass.

When the image is seen through the glass upon which it is taken, it cannot be colored with very great success, as it cannot be seen through the reduced silver forming it. This forms a more or less opaque surface; but in point of economy the single glass is preferable. Yet I would not recommend such economy, for I consider that a good impression ought to be well put up, and the welfare of the art fully substantiates that consideration.

Many ways have been devised for putting up pictures I have produced pleasing effects upon colored glasses: for instance, a picture on a light purple glass has a very pleasing effect; also in some other colors. I have also used patent leather for backing the image.

I have produced curious and interesting results by placing a piece of white paper, or coloring white the back of the whites of the image, and then blackening over or around this. By this means the whites are preserved very clear.

Positives for Pins, Lockets, etc.—I employ mica for floating the collodion on, as it can be as easily cut and fitted as the metallic plate in the daguerreotype; and positives taken upon fine, clear, transparent mica, are fully equal to those taken upon glass, and yet they are ambrotypes.

Mica is an article familiar to every one, as being used in stoves, gratings, etc.

The method of using it, is to take the impression on a thick piece, and then split it off, which can readily be done in the most perfect, thin, transparent plates; it is equally as thin as tissue paper, and can be cut as easily. The thickness of the piece upon which the impression is taken is of no moment, since it can be reduced at pleasure and is more easily handled while thick.

Observations on the Positive Collodion Process.

Fogging.—There are numerous causes which will produce fogging: the principal ones will be mentioned. One is the admission of light upon the collodion. This maybe from a want of closeness of the dark room, the tablet,[E] the camera, or by accidental exposure. The method to locate the particular cause is to, first, when the glass is taken from the nitrate bath, let it stand for sufficient time to drain, then pour on the developer, and if the coating assumes a mistiness, or light-grey color, the fault is in the dark room; again, if the plate, after it has been treated with the developer and fixed, is clear, then also the fault is there. Now try the tablet in the same manner, and if not there, try the camera, and the proper location will be found.

"Decomposition by exposure to light or by long keeping, even in the dark. The author conceives that it is possible for organic matter alone to produce, after a time, a partial decomposition of solution of nitrate of silver, sufficient to prevent it from being employed chemically neutral, but probably not much interfering with its properties in other respects.

"Use of rain water or of water containing carbonate of silver being perfectly neutral and from nitric acid. This difficulty is not a theoretical one only, but has actually been experienced. Rain water usually contains ammonia, and has a faint alkaline reaction. Pump water often abounds with carbonate of lime, much of which, but not the whole, is deposited on boiling. To remove the alkaline condition, add acetic acid, one drop to half a pint of the solution.

"Partial decomposition of the bath, by contact with metallic iron, with hyposulphite of soda, or with any developing agent, even in small quantity. Also by the use of accelerators, which injure the bath by degrees, and eventually prevent its employment in an accurately neutral state.

"Vapor of ammonia, or hydrosulphate of ammonia, escaping into the developing room."

Spots.—One principal cause of spots is dust. The operating room should be kept as free from this as possible, and instead of its being dusted, it should be wiped with a damp cloth. Specks or flakes of iodide of silver are often found in the nitrate bath. These sometimes occur by an ever-iodized collodion, and sometimes by collodion falling off while being silvered. When this occurs, the nitrate of silver solution should be filtered. A new sponge or a tuft of cotton is a good article to filter nitrate of silver solution through. A small particle of light finding its way upon the plate, will produce a spot. Another and very frequent cause is, putting the slide of the tablet down rapidly, causing it to spatter upon the plate the solution which has drained off from it. This paper will be opaque when viewed by reflected light, and dark when viewed by transmitted light. Occasionally a sort of transparent spot will appear: this may be traced to a want of sensibility of the iodide of silver. Large transparent spots frequently appear by the operator's pouring the developing solution upon one place, and washing off the small quantity of nitrate of silver necessary to develope the image. This will be easily detected, and can be obviated by flooding the most of the surface of the glass with a steady stream of the developer.

Stains and Lines.—If the glass be allowed to rest for an instant with one portion of its surface in the silvering solution and the other out of it, it would cause a streak across; hence the necessity of totally immersing it with one firm, steady motion removing the glass before it has been thoroughly wetted, and the ether and alcohol allowed a uniform action over the entire surface. A plate should not be disturbed in the bath until it has been in a full minute at least.

Irregular Lines are often caused by using the developing solution too strong, or by not pouring it evenly over the plate at once. Should it be allowed to rest in its progress, if but for an instant, it will leave its line. Sometimes spangles of metallic silver appear: these are caused by the presence of too much nitric acid in the developer for the proportion of iodide in the film and the strength of the bath.

There are other phases connected with the practice of the positive process, which it would be almost impossible to commit to paper, and cannot be so explained as to be perfectly comprehended by the new experimenter. It is absolutely necessary for all to observe every little point noticed in the foregoing pages, and at the same time exercise some good judgment, and no one need hesitate through fear of not being successful.

PRACTICAL DETAILS

OF THE

NEGATIVE PROCESS.

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