This section is from the book "Complete Self-Instructing Library Of Practical Photography", by J. B. Schriever. Also available from Amazon: Complete Self-Instructing Library Of Practical Photography.
The Image Uneven. When the image is uneven and the pigment appears to adhere only in patches, the cause is due to failure to immerse the pigment in clean water before pressing it into contact with the bromide print. Both the pigment tissue and the bromide print should be brought into contact beneath the surface of the water.
Image Lacks Detail. When the image lacks detail, especially in the higher tones or the high-light of a print, the difficulty is due to one of two errors in manipulation. First, an excess of sensitizing solution remaining on the surface of the tissue and its getting upon the image before the two surfaces are squeegeed into close contact. Before bringing the pigment and the bromide print into contact, remove all superfluous sensitizing solution from the surface of the tissue by drawing the surface of the tissue once or twice along the edge of the tray. The second difficulty arises from the sensitizing solution being too strong for certain colors. For average work the proportion given by manufacturers (1 to 4) is correct. When using black tissue have a strength 1 to 3, and for lighter colors 1 to 5 or 1 to 6.
Flat Pictures And Pictures Difficult To Develop. The usual cause is hypo remaining in the bromide print. The greatest care should always be exercised in thoroughly fixing in the plain hypo bath and then washing thoroughly in clear water the bromide print that is intended to be employed in the Ozobrome process. Difficult development may also be caused by allowing the pigment tissue to remain too long in contact with the bromide print and transfer paper.
Specks And Air-Bells. At all stages of the process great care must be exercised to avoid air-bells and if they form, immediately remove them. Bear in mind that all surfaces should be brought into contact only under water or with a layer of water between them, and it is very important that the water itself should be absolutely free from air-bells. Special caution is necessary when employing the transferring process, as you must look out for air-bells after stripping the tissue from the bromide print. The transfer paper lying in the same dish with the tissue is very apt to cause air-bells which emanate from the transfer paper to adhere to the tissue and thus cause trouble. The transfer paper should be soaked in a tray of water by itself, and when extra heavy paper is employed considerable soaking is necessary in order to remove all air that is in the paper. The heaviest transfer paper, and especially the etching paper, should soak at least one-half hour before using. It is an excellent plan to have a separate tray for each process, and then no serious difficulty will result.
410. Water used must be free from grit or any small particles of dirt, as these have a very annoying habit of coming in contact with the surface of the tissue and adhering, causing specks on the resulting print. Cleanliness, therefore, is the preventative and if a difficulty does occur, spotting is the only remedy. Another cause for air-bells is lack of squeegeeing or bringing into perfect contact the pigment tissue and the bromide print. All air must be excluded from between these two surfaces. If, however, the tissue and the bromide print were brought into contact beneath the surface of the water, air-bells cannot get between them.
Frilling. There are four causes for this difficulty, as follows:
412. (a) The use of a tissue smaller than the print will almost invariably cause the frilling at the edges, on account of the edge not adhering to the bromide print or transfer paper. In every case the pigment tissue should be larger than the print you wish to reproduce.
413. (b) Tissue too wet before transferring operation. The amount of necessary soaking can only be ascertained properly by experience. If the tissue is saturated with water at this stage of the process it will fail to adhere firmly to the transfer paper. With very rough paper, lack of pressure after it is transferred, or insufficient time between the transferring and the development, may give rise to the same trouble.
414. (c) Development taking place too soon after the squeegeeing operation. If other instruction has been followed the print should remain 20 minutes after squeegeeing before development.
415. ((f) Insufficient squeegeeing. The squeegee should be used firmly, but not roughly. Firm, even pressure should be cultivated, but great care must be exercised not to strike any portion of the print when bringing the squeegee into contact with it, as lines are apt to be formed when this is done.