278. Red marbled lines, and a quantity o f minute red specks after toning, hut not visible before, are seen on the prints. There is no remedy for such paper, It is badly albumenised; the lines are formed by the albumen running unevenly down to the edges, and the red specks byndust tset-ding upon the surface when drying. Minute air - bubbles in the albumen are also a frequent cause of red specks. All paper causing these should be rejected at once and sent back to the dealer.
279. The paper has a marbled appearance after silvering. This is caused by dust and scum floating upon the surface of the silver solution, remains in the bath in solution as a neutral nitrate, and the carbonic acid combines with an equivalent of silver oxide to form carbonate of silver, which falls to the bottom as a white precipitate. The nitrates of ammonium and sodium in the bath can only be regarded as idle matter, better out of the way. - F. M. Spencer.
I used to make a great mistake in testing the printing-bath by using blue litmus-paper, supposing that if it did not turn red that it was alkaline; but I was continually tormented with what is termed measles, until, through the kindness of Mr. Hearn, I was advised to use red litmus - paper, and when that turns slightly blue I am sure of an alkaline bath. It should be tested every morning after it is filtered, before using, and if not alkaline add ammonia. Never add muriatic acid just before using; if too weak, add a few crystals of silver and a little camphor, and go ahead with your silvering. Keep camphor in stock prepared as follows:
C. M. French.
278. Sometimes there is a want of affinity between the sensitizing solution and the albu-menized paper. The cause is a simple one, easily rectified. The silver solution is too strong for the paper, and thus causes red globules and zigzag or marbled lines. The difficulty occurs only when the paper is too heavily albumenized. Papers coated with weak albumen, sensitize evenly with silver solutions on any strength, simply because the pores are left open to exercise capillary suction. It is a curious fact that heavily albumenized papers require the weakest silver bath. - J. L. Gihon.
279. To take albumen out of silver solution for printing, dissolve one ounce of gum camphor in six ounces of ninety-five per cent, alcohol; of this, add to any positive silver bath (that has albumen in it, or becomes black or foul) a few drops at a time, and shake it well; and by the solution becoming contaminated with albumen. Always filter before use; and if the solution remains in the dish any length of time, draw a couple of strips of paper over it to remove the scum.
280. Red patches formed during toning. These are caused by the prints being allowed to rise above the surface of the solution, by two or more prints sticking together, and by air-bubbles forming between the prints. The remedy is to tone but a few at a time, and keep them moving in the solution.
281. Defective toning. When the prints are red after fixing, they have been insufficiently toned; when a cold blue, they have been excessively toned; when prints are toned to a blue, and get very red in the hypo, the gold bath is too strong, the gold attacking and toning the surface before it has time to penetrate through the print. The remedy for this is obvious.
if the bubbles do not break when the bottle is set down, add a little more until it ceases to froth or bubble, then filter at once. If the silver should turn after filtering, add a very few drops of permanganate of potash, which will clear it up at once. This last should only be added drop by drop in quantum suf., else the albumen surface will be injured. - John R. Clemons.
For removing albumen from silver baths, to save alcohol, place your silver bath in an evaporating - dish and reduce it to about one-third or so, then pour it into a common glazed pie-dish, or, if not convenient, any ordinary flat dish will do. Let it be kept for that purpose. When the solution is cold, add about an equal quantity of alcohol, then light with a match; it should burn about five miuutes. Place the bath where the air will not affect the flame. When the flame expires, the solution will be entirely clear of red or dark matter, and the albumen will be found coagulated at the bottom of the dish, and can be readily removed by filtration. By this process any albumen bath - no matter how dark or how filthy - can be quickly and effectually cleansed. - John R. Clemons.
281. My treatment of the gold I find to be well adapted to the printing process. My ton-ing-bath, stock solution, is formed of
Chloride of Gold,.....
Acetate of Sodium,....................................
With my prints, I find no difficulty in using it immediately, but prefer not to use it until a few hours after making. When required for use, I take water sufficient to contain the prints made from four sheets of paper, and to this I add one ounce of the stock solution. This is sufficient to tone four sheets. It will be observed that the stock - solution contains one grain of gold for each ounce of water. It follows then that one grain of chloride of gold will tone four sheets of paper. This may be considered too much paper for the amount of gold, seeing that the usual direction prescribes a grain of gold for each sheet. Dr. Vogel, referring to this subject (see Handbook, p. 139), says, " We have to calculate 0.06 gramme equal to one grain of gold for every sheet of paper," whereas my regular practice is to tone the
282. The finished prints have a mark, mottled appearance when viewed by transmitted light This is earned by imperfect fixing, Either hypo solution is too weak, "or the prints were not allowed to ramain in it long enough. They should be left in the solution until you can see nothing but the fibre of the paper in the white, parts of the print when held up to the light If this not done, they are apt to fade or turn yellow in a short time.