The Optical Magic Lantern Journal (June 1894)

The Optical Magic Lantern Journal and Photographic Enlarger. 113 forward by both surfaces being exposed to contact with the air. The process used in making “ Blair's Film” can be briefly outlined as follows: The base or the basic film taking the place of glass is formed by spreading the liquid material on an endless moving surface, for instance a cylinder, and allowing this material, which is formed into the basic film to remain on this surface only sufficient time to become solid enough to be handled by the machinery without injury, then stripped and kept in motion over rollers, thus allowing the air to be passed over both surfaces equally until sufficiently seasoned, then carried to the coating machine in the Non-actinic department where the sensitive emulsion is applied, and the completed Film is arranged on devices which still expose both sides of the Film until the drying of the sensitive emulsion is completed. Thus it will be seen that from the time the basic film leaves the moving surface, until the completed sensitive film is finally cut into proper widths and lengths, and wound or put in cut sheet packayes, the air has constant access to both sides, and the time of seasoning the basic film before coating can be prolonged to any extent desirable by extending the area over which it travels, while as this process is carried on in compartments used for no other purposes, the temperature within them can be kept at any desired degrce of heat, and the air changed by propellers as often as necessary. It is surprising the great difference actual tests have shown in the time required to season by this method compared with that of drying where no direct current can be brought in contact with the surfaces, even in a well ventilated room. When the film is hermetically. in contact with a non-conductor of heat and air, the difference in time is added to manifold. It will be seen that by this process, basic film could be made of any length (even miles), and that the relation of the two processes are similar to that of forming fabrics in frames, and that of weaving by modern looms. The ‘ground glass" surface of Blair's Film is not produced by sand blasting the basic film itself, as is generally supposed (which would be not only an expensive but dusty and dangerous process), but by giving the travelling surface on which the film is formed a fine grain surface, which is reproduced on the film, and once prepared goes on giving the impression to’ miles of film without additional cost, labour, or dirt. As to the keeping qualities of film properly made, and with all damaging properties removed from the base compared with glass plates, everything > seems in favour of film as the chief destroyer of the sensitive coating of emulsion is air (moist air, impure air). With plates the non-flexibility of the support makes it unsafe to pack the surfaces together, and even when so packed the air is not kept fron the surface, while even with cut sheet films it is almost entirely so, the flexibility of the support causing the sheets to be in quite perfect contact. With film in rolls the surfaces are practically hermetically sealed from the air, and a roll of film as wound by the manufacturers, with box and wrapping removed, could be exposed to daylight without its effecting the sensitive surface at the ends of the roll, while but a few wraps of the roll would be found effected by the exposure. The advantages, in weight, non-halation, and freedom from breakages, need not, I feel be argued. Many faulty batches of film have been made, but have they (even comparatively—and by the imperfect method) been as numerous as dry plates, or any other of the new processes which have revolutionized the method of making photographs in their early stages. Film photography will be found interestiug to watch in its onward march. :0: The Planet Electric Lamp. THE new “ Planet’ electric lantern lamp which is on view at 67, Piccadily, W., has, we learn,