283. Yellowness of the prints when finished. Several causes will pro-duce this, such as leaving the prints in the hypo longer than necessary to number of sheets suited; and I have frequently, for experiment, put as many as seven sheets at once into the bath, with only one grain of gold, and have succeeded in toning the whole quantity well and thoroughly. - W. II. Sherman.
Care should be taken not to use too weak a gold solution. I like this:
A. - Chloride of Gold......
B.- Acetate of Soda,..................
Pour the solution A into the solution B; to this four drops of a saturated solution of cupric sulphate should be added, and the whole allowed to stand for a few days. The pictures should be toned only until the half-tones appear somewhat bluish. The proper tone may be judged by watching the progress of the toning of the face specially. The operator will perhaps fear that his results are too red, but it will be found that the pictures are properly toned and the whites beautifully colored after fixing. A weak fixing - bath, say one to ten, is recommended. - Herr Richter.
The process I follow is: Pour out a sufficiency of your old bath, and add your gold about fifteen minutes before toning, stirring well; then, just before toning, add enough saturated solution of sal - soda to render the whole slippery to the touch. Do not try to make it just alkaline, and test with litmus; for it will not work. It will only bleach, and leave the halftones dirty and bricky. So do not be afraid, but pour in till it is alkaline to the touch. The amount may be from one - half ounce to one ounce of the saturated solution to the gallon of bath. This will tone brown, blue, or black; but if the latter is desired, of course an addition of chloride of lime helps the matter, but also sooner spoils the bath. - M.L.Daggett..
282. To secure permanent prints, wash them in warm water, but do not boil them. All sorts of learned reasons have been given concerning the formation of insoluble compounds and their destructive nature and effects; but long years of experience have taught me that the best preventive against fading is warm-water washing, either in winter or summer, Since I adopted this plan, many years ago, I have never seen one of my prints fade; while those of others alongside have exhibited symptoms of yellow fever, increasing in intensity until they became defunct or melancholy evidences of carelessness. Some may say - " But warm-water washing injures the tone." I say - "Not necessarily so." But, if it does, be bold and honest enough to sacrifice tone for permanency. - J. Werge.
288. Nitroprusside of soda is one of the most delicate tests for alkaline sulphides known. This salt requires about two and a half parts of cold water for solution. Its solution is de clear them; acidity of the fixing - bath (this can be avoided by using carbonate of ammonia with the hypo, or where this cannot be obtained, a little bicarbonate of soda or a drop or two of ammonia, will neutralize all acidity); the hypo - bath used until decomposition takes place. The latter is a fruitful cause of yellow prints. Never use it more than twice, and it is much better to make it fresh every time. Extreme warm and sultry weather will sometimes turn some samples of paper yellow beyond redemption. The same effect is produced by keeping paper some days between the time of sensitizing and printing. Frequent tests should be made, if danger is suspected.
284. Yellow patches and stains. These are caused by careless manipulations, such as finger-marks upon the surface of the paper; washing the prints in imperfectly cleaned dishes, or in the tank that received the prints from the hypo the day before; hypo on the fingers while toning. If there is the least trace of silver in the tank when it receives the prints from the hypo, they will all be stained, and vice versa. If there is the least amount of hypo in the water while washing the silver out of the prints, they will be stained. To know the above causes is to know the composed by the sun's rays. The crystals are rhombic and of a splendid ruby color, and give a most beautiful violet tint with soluble sulphides - such as hyposulphite of soda, etc. - John R. ClemonS.
284. Now for the secret of pure whites, and the only way you can get them pure. Procure your half ounce of aniline blue, letter R, and dissolve it in sixteen ounces of water. When your fixing - bath is made up, add from thirty to forty drops of the blue to every forty ounces of fixing - bath. Fix your prints from twelve to fifteen minutes, and remove to a strong solution of salt and water. Let them remain five minntes, and then gradually dilute with fresh water, so that the change of temperature will not be so sudden, and you will never be troubled with blisters, and will always have pure whites. I have this from Mr. J. R. Clemons. - Frank Thomas.
The "aniline blue " process, as recommended by me, will be found very advantageous, giving to new prints delicate, pure whites, attainable by no other means, and restoring old or yellow prints to their original purity. Besides improving the general tone of every - day work, it is of immense advantage in copying old or yellow photographs, which give no contrast whatever. Immersion in the aniline solution restores the whites, and enables the photographer to get a negative with all the detail of the original. The manner of using is as follows: Dissolve one-half ounce of powdered aniline (known as " water - blue, letter R,") in sixteen ounces of water. This is the stock-solution. When you mix your fixing - bath, add from thirty to forty drops of the blue solution to every forty ounces of fixing solution. This will produce pure whites, and will also prevent blistering. If you want a blue tint, or moonlight effect, take the print from the hypo and immerse in a saturated solution of alum, and the blue is permanent. If the color is too deep for you, immerse the print in a saturated solution of borax, and you may lessen the tint as far as you please. - John R. ClEmons.