PRINTING PROCESSES: THE BLUE PRINT.
The number of processes used for photography are many. The very simplest is the blue-print paper. This quality is not the only one which recommends it alike to the beginner and the advanced amateur. It is nearly equal to the best silver prints in detail and clearness, and, unlike them, is absolutely permanent. It does not require any manipulation after printing except washing in clear water. It is only half the price of silvered paper, and if prepared at home is still less expensive. Then blue paper is specially adapted to water pictures and to landscapes where there are plenty of clouds in the sky, and to those which have a long perspective with hills or mountains in the distance.
The ready-prepared paper costs twenty cents for a 4 x 5 package containing two dozen sheets. That prepared at home will cost about five cents for the same quantity.
The process of printing with blue paper is as follows: Place the negative in the printing-frame, glass side out, lay a sheet of blue paper on the film side, fasten in the frame and expose to bright sunlight. Blue prints may be made on a cloudy day, but the quicker they are printed the clearer and sharper will be the picture. Print until the shadows are slightly bronzed—that is, have a sort of metallic or shiny look, and are a bluish-green in color.
Take the print from the frame and place it face up in a tray of clear water, and let it stand in the sun for a minute or two, and then wash for fifteen or twenty minutes in running water. If one has not running water, wash the print in a few changes of water till the water ceases to be tinged with the blue color of the print. If the fine details of the picture wash out, the picture has not been printed long enough. If the high or white lights in the picture are tinged with blue, then the picture has been printed too long.
After the print is washed sufficiently, lay it between two clean pieces of white blotting-paper to absorb the moisture, then pin it up by the corner to dry.
It is very easy to sensitize the blue paper. Any unglazed paper will answer, but the Rives paper is the best. The following formula was sent a few days ago by Sir Knight Willis H. Kerr, University of Omaha, Bellevue, Wisconsin:
No. 1.
| Citrate of iron and ammonia | 1 oz. |
| Water | 4 " |