Oily Lines. 1. Lifting the plate out of the nitrate hath before it has been immersed sufficiently long to be thoroughly wetted, or before the ether upon the surface has been washed away. 2. Redipping the plate in the nitrate bath after exposure in the camera, and pouring on the developer immediately; if a few seconds be not allowed for the purpose of draining off the excess of nitrate, the pyrogallic acid will not readily flow over the film. 3. From too small a quantity of fluid having been employed to develop the image. In this case, the whole plate not being thoroughly covered during development, the action does not proceed with regularity. 4. Opaque, oily, diagonal markings are very commonly produced by pouring off the developer, and examining the plate by transmitted light, without washing the film; the solution of pyrogallic acid runs into lines which show after fixing. 5. Addition of old collodion in making a new bath. The ether mixes with the bath and gives a greasy appearance to the immersed plates.
Transparent Marks like Curtains. - These occur at the edge of the plate which is most depending in the camera, and are produced by the bath solution draining down, or sometimes ascending by capillary attraction, from the corners of a dirty slide. They are most common with a gelatinous,simply - iodized collodion, and are seen in cold and damp weather more than in hot and dry weather. To obviate their occurrence, allow the ether to evaporate from the film before dipping, so that the bath solution may run completely off; or turn the plate round, that the upper and dryer part may be below; or place it across the dipper so as to bring the curtain mark to the side of the picture, where it will be less visible. - T. Frederick Hardwich.
178. A generally wretched negative, that seems to possess all the ills which occur in negative - nuking combined, will look thus: In tin - find place, it is full of pinholes and large streaky patches of white scum, as if somebody had poured a solution of chalk and wain - on it; secondly, the film is thin, and the image harsh and without detail; in fact,destitute of a single good quality, First, there are two diatinct kinds of transparent spots; one kind is called pinholes, caused by a large excess of iodo-nitrate of silver in the bath, and the other kind is specks of irregular shape, such as are caused by dust, sediment in the collodion, etc.; then there are the large white patches, spoken of above, which indicate that the plate - holder is very dirty, and that, the plate not being properly drained, the silver has run down, absorbed the deleterious matter, and has again been drawn up by capillary attraction and settled upon the plate, adhering to it with great tenacity. In addition, that the hath is full of ether and alcohol, is shown by irregular greasy markings which are all over the plate; finally, the image is hard and chalky, and lacking detail, proving that the coilodion is old, red, and insensitive, or that the bath is highly charged with acid in the vain endeavor to get rid of fogging, or perhaps both.
178. Pinholes may be formed in five ways: First, dust; Second, unsettled collodion; Third, over-iodized bath; Fourth, too Strong iron solution; Fifth, over-iodized hypo. All of these have a different and distinct appearance.
1. Pinholes from dust are irregular, as regards size, and scattered irregularly over the plate. The remedy is obvious. 2. Pinholes from unsettled collodion are very numerous, and regularly scattered over the entire plate. Upon examining them, however, with a microscope, they will be found to have little tails attached to them, which indicate at once the source from which they arise. 8. Pinholes from an over-iodized bath are very numerous, scattered evenly over the plate, are sharp crystals without tails, and leave a clear spot on the glass after fixing. 4. Pinholes from too strong iron solution are caused by the precipitate of oxide of iron; they have a close resemblance to those of an over-iodized bath. 5. "When the hypo solution has dissolved as much iodide of silver as possible, it will be saturated, and, after a short time, will deposit fine crystals of iodide of silver on the plate. In this case, however, these may be detected by there being no signs of pinholes until after fixing. If there should be any doubt as to whether the bath is near a point of saturation with iodide of silver, you may easily determine the state of the bath by the following experiment: Into four ounces of water pour gradually four ounces of bath solution, and watch narrowly the time when the precipitate of iodide of silver takes place. If you can add nearly the whole amount of the bath solution before the milky precipitate takes place, the bath is far from saturation; but should this precipitate take place before much addition of the bath solution, continue to add the four ounces of solution, and stir the mixture thoroughly. Next add crystals of nitrate of silver gradually, stirring until dissolved. When the mixture just clears, and no more, test with your hydrometer, and you will see at once the state of the bath. If the hydrometer marks thirty grains, or nearly thirty grains, the original strength of the bath, your bath is nearly saturated; but if the hydrometer mark only twenty grains, or less, you need not fear pinholes from over - iodizing for some time to come. - Elbert Anderson.
179. The authorities do not always agree as to the cause of these annoying spots, and sometimes their appearance is so mysteriously sudden and so persistently continuous as to baffle even the doctors of photography themselves. It is often serviceable, when such annoyances occur, to go back mentally and think over what you have done, and mayhap the cause of your annoyance will come to you. The causes of this annoyance, at least, are well laid down in the notes.
180. There is this one agreeable thing about photographic manipulation, however: the chemicals, under certain conditions, are pretty sure to a bath not iodized sufficiently; too cold a temperature (your dark - room iodide; then add more to the bath. Plato - holders, tablets, and cameras, as well as your bottles and shelves and floor of the dark-room, must be wiped damp every day.
179. The following are frequent causes of spots on the collodion plate. First. Newly-iodized collodion. 1. Containing bromide of potassium in quantity more than the collodion will dissolve; in this case the spots will be round and transparent, thickly studding the plate. Allow twenty-four hours to subside, and draw off the upper part. 2. The collodion is free from undissolved particles of iodide, but contains a fine sediment of pyroxylin; specks from this cause are extremely minute and abundant. Three or four days' setting will clear the collodion; but very often the specks will disappear if a portion of a more intense collodion be mixed with the newly iodized. 3. The collodion is free from suspended iodide or undissolved pyroxylin, but, nevertheless, the plate shows transparent specks. In this case, the specks may be due to dust, but the remedy last given is the most likely to prove successful.
Second. Faults of the bath. 1. Newly made from impure nitrate of silver. In this case the image will be very weak as well as spotty, and the bath will require a trace of acetate. 2. Iodide of silver, previously dissolved in the bath, crystallizing upon the film. The film, in such a case, exhibits little projecting points upon the surface of the iodide before exposure in the camera, and transparent pinholes after fixing. Add to the bath a sixth part of a thirty-grain solution of nitrate of silver, not containing any iodide of silver, and remove the plate from the solution after an immersion of two minutes. Or, leave a sensitive plate in the solution all night, that the excess of iodide of silver may gradually crystallize upon its surface, and so be removed. 3. A floating film of iodide of silver upon the surface of the bath. These spots are not universally distributed, and are larger than the last. Remedy: Change the collodion or the time of dipping. 4. Deposits of reduced silver on the sides of the bath and dipper, or fragments of iodized collodion which have fallen into the solution. Spots so produced are easily recognized, and the appearance of the picture at once shows that the bath requires filtering. - T. Frederick Hardwich.