(Household Cyclopedia, 1881)[edit | edit source]
(Note: This section is normally not very useful but many people master this old art and earn good money with an old view camera, costumes of some 150 years ago, by actually taking old glass plate photographs.)
Apothecaries' weight is used throughout this article. In case of liquids the abbreviation oz. signifies fluidounce. To make Pyroxyline or Gun-cotton, suitable for Photographic Collodion.
- By nitre process: Oil of vitriol (s. g. 1.70) 6 oz.; dried nitrate of potash, 3 1/2 oz.; water, 1 oz. Mix the acid and the water in a porcelain vessel, and add the pulverized nitre, gradually stirring with a glass rod until the lumps disappear and the mixture becomes transparent. Place a thermometer in the mixture, and when it indicates between 145o and 150o Fahr., the cotton should be immersed. Take 60 grs. of clean cotton, and separate it into 10 or 12 bolls, and immerse the bolls separately, and leaving the whole in the mixture for 10 minutes. Should the temperature fall to 140o, float the cup on boiling water, and maintain it between 140o and 150o. At the expiration of 10 minutes lift the cotton with glass rods, and squeeze out the acid quickly and dash the mass into a large vessel of clean, cold water, separating the mass so as to wash it thoroughly and quickly. Complete the washing by immersion for several hours in running water, then spread it out to dry spontaneously.
- By mixed acids: Oil of vitriol (s.g. 1.845), 18 oz.; nitric acid (s. g. 1.457), 6 oz.; water, 5 oz. Mix the nitric acid and water in a porcelain vessel, then add the oil of vitriol and mix thoroughly and allow the mixture to cool to 150o Fahr., when immerse the cotton. Take 300 grs. of clean cotton, well loosened, and immerse piecemeal, so as to saturate thoroughly with the acids. Allow the whole to remain 7 minutes, after which time lift it out with the rods and wash it precisely as directed in last process.
Photographic Collodion.
Pure alcohol (s. g. 0.805), 10 oz.; pure ether (s. g. 0.725), 20 oz.; prepared cotton, 300 grs. Pour the alcohol into a 40 oz. glass bottle, add the cotton, and shake until the cotton is thoroughly wetted; then add the ether, shake well and set away in a cool, dark place for several weeks to settle. Mark "Plain Collodion." In very warm weather increase the proportion of alcohol by addition a day before use or at time of iodizing.
Iodizers for Photographic Collodion.
Iodide of ammonium, 90 grs.; iodide of cadmium, 30 grs.; bromide of ammonium, 40 grs.; alcohol (8.10), 10 oz.
Or, iodide of magnesium, 200 grs.; bromide of cadmium, 50 grs.; alcohol (810), 10 oz. Pulverize the salts, and add gradually to the alcohol, commencing with the bromide; shake until completely dissolved, and set away in a dark place. Mark "Iodizing Solution."
To Iodize Collodion.
Plain collodion, 3 oz.; iodizing solution, 1 oz. Mix and set away in a dark, cool place 12 hours before using. Any of the ordinary iodides or bromides can be substituted in the above formula.
Sensitizing Baths.
For positives: Pure re-crystallized nitrate of silver (437 gr.), 1 oz.; pure nitric acid, 3 minims; alcohol, 2 drs; distilled water, 10 oz.; iodide of potassium, 1 gr. Dissolve the nitrate of silver in 3 oz. of the distilled water, add the iodide of potassium, shake and allow to settle; test for acidity with blue litmus paper, and, if present, neutralize carefully with a solution of carbonate of soda. When neutral, add the remaining 7 oz. of distilled water, filter and add the alcohol and nitric acid, and the bath is ready for use.
For negatives: Pure recrystallized nitrate of silver, 1 oz.; glacial acetic acid, 5 minims; alcohol, 3 drs.; iodide of potassium, 1 gr.; distilled water, 10 oz. Dissolve the silver in 8 oz., and treat precisely as for bath for negatives, observing that it is to be acidified with glacial acetic acid in place of nitric acid.
These baths should be kept in a dark place, and always show an acid test. When out of order, boil for a few minutes, add one-tenth volume of distilled water and restore to the original strength by adding strong solution of crystallized nitrate of silver in distilled water, and acidifying with the proper acids.
Developers.
For positives: 1. Pure sulphate of iron, 150 grs.; glacial acetic acid, 6 fl. drs.; water, 10 oz.; nitric acid, 2 minims. Dissolve the sulphate of iron in the water, and add the acetic and nitric acid and cork tightly.
- Sulphate of iron, 480 grs.; nitrate of baryta, 320 grs.; alcohol, 1 oz.; nitric acid, 30 minims; water, 10 oz. Powder the nitrate of baryta and dissolve in the water warmed; when dissolved, add the powdered sulphate of iron stirring for a few minutes, filter, and when the liquid becomes cold, add the nitric acid and alcohol separately. Bottle and cork tightly.
For negatives: 1. Pyrogallic acid, 10 grs.; glacial acetic acid, 3 drs.; distilled water, 10 oz. Dissolve the pyrogallic acid in the water, add the glacial acetic acid, cork tightly. 2. Sulphate of iron and ammonium, 2 oz., or sulphate of iron, 1 1/2 oz.; glacial acetic acid, 1/2 oz., or acetic acid No. 8, 1 1/2 oz.; alcohol, 1/2 oz.; distilled water, 10 oz. Add to the distilled water in the order indicated, the iron-salt to be first dissolved. In warm weather this developer requires dilution, and must be washed from the plate the instant the details appear.
Fixing Solutions.
For positives: Cyanide of potassium, 120 grs.; nitrate of silver, 6 grs.; water, 10 oz. When this solution requires more than a minute or two to clear the picture, add a small amount of cyanide of potassium.
[This solution is highly poisonous, and should not be allowed to touch unsound skin, nor should the fumes be breathed.]
For negatives: The above solution of cyanide of potassium answers very well, or hyposulphite of soda, 10 oz.; water, 10 oz.; ether, 30 minims.
Strengthening or Intensifying Solutions
Should be employed after the picture has been developed, fixed and carefully washed:
Nitrate of silver, 200 grs.; distilled water, 10 ounces. Or, Bi-chloride of mercury, 30 grs.; distilled water, 40 oz. Cleaning the Glass Plates.
Before washing the glasses, each square should be roughened on the edges and at the corners by means of a file, whetstone, or a sheet of emery paper; or more simply by drawing the edges of two plates across each other. A cream of Tripoli powder and spirits of wine with a little ammonia added, is commonly employed. A tuft of cotton is to be dipped in this mixture and the glasses well rubbed with it for a few minutes.
After wiping the glass carefully, complete the process by polishing with an old silk handkerchief, avoiding contact with the skin of the hand. Leather may be used instead of silk for the final polishing; they must be first beaten, then washed in pure water, dried in the sun and well pulled out until they are soft and yielding. Before deciding that the glass is clean, hold it in an angular position and breathe upon it.
Other modes of cleaning glasses have been recommended, of which, perhaps, the residues of collodion are the most simple. Add a fluidrachm of water to the ounce of collodion until the pyroxyline begins to form a white deposit not redissolved on agitation: this will prevent the collodion from evaporating too quickly. Then pour a little upon the glass and rub with a tuft of wool or piece of cambric. Clean off with a second piece, and finish with cloth and leathers as before, no water will be required. New glass plates are frequently dotted on the surface with little gritty particles, which consist of carbonate of lime. They are not removed by potash or any alkali, but dissolve readily in a diluted acid, such as oil of vitriol, with about four parts of water added, or dilute nitric acid.
Lea's Cleaning Solution.
Water, 1 pt.; sulphuric acid, 1/2 oz.; bichromate potash, 1/2 oz. The glass plates, varnished or otherwise, are left, say 10 or 12 hours or as much longer as desired, in this solution, and then rinsed in clean water and wiped or rubbed dry with soft white paper. It removes nitrate of silver stains from the fingers.
Coating the Plate.
When the collodion is properly cleared from sediment, take a glass plate, previously cleaned, and wipe it gently with a broad camel's-hair brush in order to remove any particles of dust which may have subsequently collected. If it be a plate of moderate size it may be held by the corners in a horizontal position, between the forefinger and thumb of the left hand. The collodion is to be poured on steadily until a circular pool is formed extending nearly to the edges of the glass,
Figure 21.1: Coating the Photographic Plate.
By a slight inclination of the plate the fluid is made to flow towards the corner marked 1 in the above diagram, until it nearly touches the thumb by which the glass is held; from corner 1 it passes to corner 2 held by the fore-finger, from 2 to 3 and lastly, the excess poured back into the bottle from the corner marked No. 4. It is next to be held over the bottle for a moment until it nearly ceases to drip and then by raising the thumb a little the direction of the plate is changed so as to give a rocking movement, which makes the diagonal lines coalesce and produces a smooth surface.
The operation of coating a plate with collodion must not be done hurriedly, and nothing is required to ensure success but steadiness of hand and a sufficiency of the fluid poured in the first instance upon the plate.
With regard to the time which ought to elapse between coating and dipping, observe the following: After exposing a layer of collidion to the air for a short time, the greater part of the ether evaporates and leaves the pyroxyline in a state in which it is neither wet nor dry; but receives the impression of the finger without adhering to it. This is termed setting, and when it takes place the time has come for submitting the plate to the action of the bath.
When the plate is ready, rest it upon the glass dipper, collodion side uppermost, and lower it into the solution by a slow and steady movement and let it remain until the oily appearance on the surface disappears.
Exposure.
After the plate has been taken out of the bath it should be exposed and developed with all convenient despatch, otherwise the film will become partially dry, the developing solutions will not flow easily, and the negative will be weak and metallic.
Development.
The pyrogallic acid solution having been previously measured out (about 3 drs. for a stereoscopic plate or a plate 5 X 4, 1 oz. for a 9 X 7, and 12 drs. for a plate l0 X 8), hold the glass in the band in the same manner as when coating it with collodion, and flow the liquid on evenly.
Development with Sulphate of Iron.
This reducing agent developes the picture so rapidly, when the collodion contains only iodide, that its employment requires care. The solution should be thrown on to the plate rather quickly and with a sweep. In the course of a few seconds the image appears in all its parts, and the liquid on the film shows signs of commencing turbidity. When this happens, the developer must be poured off immediately, and the plate washed with water, otherwise the shadows will be misty from adherent particles of silver. Plates developed with sulphate of iron may be further blackened by washing the film and pouring over it a 20 gr. solution of nitrate of silver, followed by a second application of sulphate of iron. A better process, however, is to wash away all traces of the iron salt by a stream of water applied for a few seconds, and then to mix the ordinary solution of pyrogallic acid with nitrate of silver.
Fixing and Varnishing the Negative.
Wash the film gently with water, and pour the solution of hyposulphite on and off until the whole of the iodide has been cleared away. The solution of hyposulphite becomes nearly black after a time, but this is of no importance, some operators considering that even a preliminary washing to remove the pyrogallic acid solution is unnecessary. A thorough washing after the hyposulphite will be essential. After the negative has been washed flow it over with a solution of gum Arabic, stand it on clean blotting-paper to dry; otherwise dust will ascend the film by capillary action, and give an appearance as if impurities had drained down from above. It is important that the plate should be dried by artificial heat before varnishing, and the negative will also look more neat if a damp cloth be first run along the edge with the finger and thumb, so as to scrape away the collodion, and leave a clear margin of 1/8 to 1/4 of an inch all round. After doing so remove with the nail or a camel'shair brush any loose or detached particles of collodion, which otherwise might be washed on to the image by the varnish, and produce a spot.
To Adjust Camera for Chemical Focus.
Take a photograph of a printed sheet with the full aperture of the portrait lens, the central letters being carefully focussed as before. Then examine at what part of the plate the greatest amount of distinctness of outline is to be found. It will sometimes, happen that whereas the exact centre was focussed visually, the letters on a spot midway between the centre and edge are the sharpest in the photograph. In that case the chemical focus is longer than the other, and by a distance equivalent to, but in the opposite direction of, the space through which the lens has to be moved, in order to define those particulars sharply to the eye.
Direct Positives on Glass.
In developing a glass positive, the solution of sulphate of iron should be flowed evenly over the film, and in some quantity, so as to wash off a portion of nitrate of silver into the sink.
Pyrogallic Acid Developer.
Forty grs. of pyrogallic acid being dissolved in 1 oz. of glacial acetic acid, and 20 minims added to 1 oz. of water when required for use. The strong solution becomes black from decomposition in the course of a few weeks, but when diluted it has only a faint yellow tint, and is tolerably effective in bringing out the image. In place of acetic acid strong alcohol may be used as a solvent, 1/2 a dr. of pyrogallic acid being dissolved in 1 oz. of spirit, and 20 minims of the resulting liquid added to each oz. of acidified water. No attempt must be made, however, to combine acetic acid and spirit in one solution, since abundance of acetic ether would be generated by so doing. These plans of preparing a concentrated developer are useful for a few weeks' keeping, but are not recommended for an unlimited time.
To Copy Engravings.
To photograph a full-sized steel engraving on a plate not larger than 7X6 or 5X4, is a very simple operation, and no special directions will be needed. Remove the engraving from its frame (the glass would cause irregular reflection), and suspend it vertically and in a reversed condition, in a good diffused light, placing a black cloth behind it, if any bright reflecting surface be presented to the lens. Point at it a camera mounted with a portraitlens, and if the image upon the ground glass appears misty towards the edge, make a diaphragm, and place it in front of the anterior glass. Instead of a portrait-lens an ordinary view-lens may be used, and as the field to be covered is small, a comparatively large diaphragm will suffice.
Be careful not to over-expose the plate, develop with pyrogallic acid, and fix with hyposulphite.
Copying Prints.
The additional deposit obtained, as above described, will often be found sufficient, and when such is the case the method is to be preferred, because the half-tones of a photograph are easily obliterated by too much intensifying. In the case of large copies of maps taken with orthoscopic lenses of long focus, the iodine method proves insufficient, and the fine lines of the drawing become partly obliterated during the prolonged development. In such a case it is advised to develop the plate only partially in the first instance, and to fix it with cyanide of potassium; then to intensify twice with pyrogallic acid, citric acid, and nitrate of silver, and lastly to treat the plate with the two following liquids: No 1. Iodine, 6 grs.; iodide of potassium, 12 grs,; water, 6 oz. No. 2. Sulphide of potassium, 1 dr.; water, 6 oz.
Apply No. 1, either in the yellow room, or in the daylight, until the whole of the image is converted into iodide of silver, and the deposit appears yellow throughout. Then pour water on the image from a jug, and apply No. 2, which must be allowed to remain until the yellow color changes to a deep reddish-brown. Lastly, dry the plate, and varnish in the usual way.
Stereoscopic Pictures.
Photographs for the refracting stereoscope are taken with small lenses of about 4 1/2 inches focus. For portraits a camera may advantageously be fitted with two double-combination lenses of 1 3/4 inches diameter, exactly equal in focal length and in rapidity of action. The caps are removed simultaneously, and the pictures impressed at the same instant. The centres of the lenses may be separated by 3 inches, when the camera is placed at about 6 or 8 feet from the sitter. Pictures taken with binocular camera of this kind require to be mounted in a reversed position to that which they occupy on the glass, or a pseudoscopic effect will be produced. The negatives may be cut in half, the right half being printed on the left side, or the finished prints may be removed before mounting.
Stereoscopic Transparencies.
Sensitive films prepared by Russell's Tannin Process. Place the negative and the prepared plate in contact, and squeeze them together in an ordinary pressure-frame; not too strongly, however, or it will probably be found, after throwing off a few impressions, that the negative has been scratched. Lay a strip of black velvet behind the sensitive film to absorb stray light.
Fixing Bath.
Take of hyposulphite of soda, 1 oz.; water, 6 oz. Dissolve without filtering, and preserve the solution in a stockbottle ready for use.
Paper Prints.
Albuminized Paper.
Formula 1. - Take of chloride of ammonium, 200 grs.; water 5 oz.; albumen, 15 oz. Chloride of barium is sometimes used in salting paper, instead of chloride of ammonium, but is contraindicated when the alkaline goldtoning process is adopted, since the carbonate of soda would throw down carbonate of baryta in the paper.
When pure albumen is used without water, from 5 to 8 grs. of salt to each ounce will be sufficient. The less the quantity of salt the warmer the color, but it must not be so far reduced as to injure the contrast and depth of shadow in the print.
If distilled water cannot be procured, rain-water, or even common spring-water, will often answer the purpose. For the albumen use eggs nearly fresh, and be careful that in opening the shell the yolk be not broken. Each egg will yield about one fluidounce of albumen.
When the ingredients are mixed, take a bundle of quills or a fork, and beat the whole into a perfect froth. As the froth forms it is to be skimmed off and placed in a flat dish to subside. The success of the operation depends very much upon this part of the process, for, if the albumen be not thoroughly beaten, cakes of animal membrane will be left in the liquid, and will cause streaks upon the paper. When the froth has partially subsided transfer the liquid part to a tall and narrow jar, and allow to stand for several hours, that the membranous shreds may settle to the bottom, then pour off the upper clear portion, which will be fit for use. Albuminous liquids are too glutinous to run well through a paper filter, and are better cleared by subsidence. Lower the paper on the liquid by one steady movement, since, if a pause be made, a line will be formed. Some papers are not readily wetted by the albumen, and when such is the case a few drops of spirituous solution of bile, or a fragment of the prepared oxgall sold by the artiste' colormen, will be found a useful adjunct. Care must be taken, however, not to add an excess, or the albumen will be rendered too fluid, and will sink into the paper, leaving no gloss.
To render the Paper Sensitive.
This operation must be conducted by the light of a candle or by yellow light.
Take of nitrate of silver, 60 grs.; distilled water, 1 oz. Prepare a sufficient quantity of this solution, and pour it out into a porcelain dish. After it has been a short time in use, the albumen, dissolved out of the papers, will cause a greasy scum to form upon the liquid, which, if allowed to remain, produces marble stains upon the sensitive paper; it must therefore be removed by folding a strip of blottingpaper the exact breadth of the dish, and drawing it lightly along the surface; lay the sheet upon the solution in the same manner as above described for the albumen.
Three minutes' contact will be sufficient with thin paper, but if a thick paper be used 4 or 5 minutes must be allowed for the decomposition. The papers are raised from the solution by a pair of bone forceps, or common tweezers tipped with sealingwax; or a pin may be used to lift up the corner, which is to be held by the finger and thumb, and allowed to drain a little before again putting in the pin, otherwise a mark will be produced upon the paper, from decomposition of the nitrate of silver. When the sheet is hung up a small strip of blotting-paper, suspended from the lower edge of the paper, will serve to drain off the last drop of liquid.
Formula 2. - Preparation of Plain Paper.
Take of chloride of ammonium, 200 grs.; citrate of soda, 200 grs; gelatine, 20 grs.; water, 20 oz. To prepare the citrate of soda dissolve 112 grs. of citric acid in 20 oz. of water, and add 133 grs. of the dried bicarbonate or sesquicarbonate of soda used for effervescing draughts.
Supposing the citric acid to be adulterated with tartaric acid, the above quantity of carbonate of soda would be too great, and free alkaline carbonate would then remain in the liquid after the neutralization was complete. The size of the paper would be liable to suffer in such a case, and the print would not be clean and bright. Excess of citric acid, on the other hand, gives very clean pictures, but they are too pale and red, without depth of shadow. Amateurs, desirous of simplifying the formula, may substitute an equal weight of "Rochelle salt" for the citrate of soda. This substance is a tartrate of potash and soda, and is sold by druggists in large crystals. Both tartrates and citrates are used for the purpose of giving a red and warm tone to the prints.
Render sensitive by floating for 2 or 3 minutes upon the solution of nitrate of silver employed for the albuminized paper.
Formula 3 - Ammonio-Nitrate Paper.
This is always prepared without albumen, which is dissolved by ammonio-nitrate of silver,
Take of chloride of ammonium, 40 grs.; gelatine, 20 grs.; water, 20 oz. Dissolve by the aid of heat, and filter when cold.
Take 10 or 12 sheets of thin Saxe paper, and, having marked the right side, immerse them bodily in the liquid, 1 by 1, with care to remove air-bubbles, then turn the batch over, and remove them singly, beginning with the sheet first immersed.
Each paper will thus be a similar length of time in the salting liquid.
This salting solution is very weak, but it must be borne in mind that the papers being immersed will take up a large quantity, and also that the ammonio-nitrate process requires less salt, inasmuch as the silver solution is to be laid on with a brush.
An ammonio-nitrate paper, yielding a very rich color, is made by salting Towgood's paper, or Papier Saxe, with a mixed chloride and citrate, in quantity exactly one-half of that advised in the last page, and afterwards sensitizing it with an 80 gr. solution of ammonio-nitrate.
Render sensitive by a solution of ammonio-nitrate of silver, 60 grs. to the oz. of water, prepared as follows: Dissolve the nitrate of silver in one half of the total quantity of water; then take a pure solution of ammonia and drop it in carefully, stirring meanwhile with a glass rod. A brown precipitate of oxide of silver first forms, but on the addition of more ammonia it is redissolved. When the liquid appears to be clearing up, add the ammonia very cautiously, so as not to incur an excess. In order still further to secure the absence of free ammonia it is usual to direct that, when the liquid becomes perfectly clear, a drop or two of solution of nitrate of silver should be added until a slight turbidity is again produced. Lastly, dilute with water to the proper bulk. If the crystals of nitrate of silver employed contain a large excess of free nitric acid no precipitate will be formed on the first addition of ammonia; the free nitric acid producing nitrate of ammonia with the alkali, keeps the oxide of silver in solution. From the presence of nitrate of ammonia, it is often useless to attempt to convert an old nitrate bath, already used for sensitizing, into ammonio-nitrate. Or, dissolve 60 grs. of nitrate of silver in 1/2 oz. of water, and drop in ammonia until the precipitated oxide of silver is exactly redissolved; then divide this solution of ammonio-nitrate of silver into 2 equal parts, to one of which add nitric acid cautiously, until a piece of immersed litmus-paper is reddened by an excess of the acid; them mix the two together, fill up to 1 oz. of water, and filter from the milky deposit of chloride or carbonate of silver, if any be formed.
Ammonio-nitrate of silver should be kept in a dark place, being more prone to reduction than the nitrate of silver.
To Apply the Liquid.
It is not usual to float the paper when the ammonionitrate of silver is used. Brushes are manufactured expressly for applying silver solutions, but the hair is soon destroyed unless the brush is kept scrupulously clean. Lay the salted sheet upon blotting-paper, and wet it thoroughly by drawing the brush first lengthwise and then across. Allow it to remain flat for a minute or so, in order that a sufficient quantity of the solution may be absorbed (you will see when it is evenly wet by looking along the surface), and then pin up by the corner in the usual way. If, on drying, white lines appear at the points last touched by the brush, it is probable that the paper was too highly salted, or that the ammonio-nitrate contained free ammonia.
Ammonio-nitrate paper is more prone to spontaneous decomposition than either albuminized or plain paper; hence it cannot be kept many hours after sensitizing without turning yellow.
Toning Bath.
No. 1. Solution of chloride of gold, 1 dr.; sesquicarbonate of soda, 10 grs.; distilled water, 6 oz. No. 2. Solution of chloride of gold, 1 dr.; ordinary phosphate of soda, 20 grs.; distilled water, 2 oz..
Examine the chloride of gold, and if its solution immediately colors litmus-paper of a bright red, add to each grain a fragment of carbonate of soda about the size of a pin's head.
The solution of chloride of gold contains a grain to each fluidrachm of water, and will keep for an unlimited time without appreciable change, previously to the addition of the carbonate of soda. The toning baths, however, must not be kept ready mixed, since they gradually become colorless and eventually lose their toning properties in great measure. A useful simplification, substituting measure for weight, consists in having always on hand an aqueous solution of carbonate of soda containing 20 grs. to the oz.; or for the second formula, a solution of phosphate of soda containing 40 grs. to the oz.
Half an oz. of the alkaline liquid would then in each case require a fluidrachm of the solution of chloride of gold and a subsequent dilution with water to the full amount given in the formula.
