Prints are too Pale when Fixed. Printing has not been carried far enough through failing to take into account the loss in depth which nearly always occurs, but to an extent which varies with the paper and the treatment used.
Pinkish Stains on the Dry Prints. These are generally caused by alkaline dust falling on the print while it is still damp. Powdered chemicals should always be handled and weighed out away from the place where the various operations are carried out. Such stains sometimes disappear if the print is washed in water which has been slightly acidified with hydrochloric acid, followed by a brief rinse in pure water.
Loss of Tone During Burnishing or Dry Mounting. The print has been heated to too high a temperature.
Gradual Fading of the Image after a Time. If the light tones become greenish or yellowish, it is usually due to the use of a combined toning and fixing bath containing no gold, or used after the gold had become exhausted, toning then being entirely due to sulphiding.
Gradual fading of the image is generally caused by incomplete removal of the livpo, which, under the influence of the oxygen and moisture of the atmosphere, gives rise to sul phuric acid, which attacks the silver image (R. Namias, 1903). A gradual discoloration of the whites of the print is usually due to incom plete fixation (use of an exhausted fixing bath).
No completely effective method is known whereby photographs on print-out papers which have deteriorated in this way can be restored. The most that can be done is to try copying the print, using an appropriate colour-filter to increase the contrast of the remaining image, and a plate or film of suitable colour-sensitiveness.
619. Failures with Development Papers. General Fogging of the Image. General fog may be caused by storing the paper under bad condi tions; by omission of the bromide from the developer (in these two cases, the margins are usually fogged) ; by wrong adjustment of ex posure to development ; or by printing a soft negative on an insufficiently contrasty paper, the working conditions having been adjusted with the object of obtaining full blacks in the shadows of the picture.
The Image has Detail but no Strength. Print ing a soft negative on an insufficiently contrasty paper, the conditions having been adjusted to obtain pure high-lights.
Grey or White Streaks. Too long development of an under-exposed print ; paper kept in a damp place. With gaslight papers, white or
light-coloured markings, especially if the paper is damp, may be caused by using a developer containing an insufficient quantity of carbonate.
Mottling : Uneven Density of the Image. Considerable under-development of an over exposed print ; paper kept in a damp place.
Black Streaks on the Whites or Light Tones ; White Streaks on the Shadows. These abrasion marks (§ 199) are due to the sheets of paper rubbing against each other when being taken from the packets ; also to their rubbing against the negative when loading and unloading the frame, or against the bottom of the dish when a sheet immersed face downwards and covered with others is brought to the top. These marks can be removed from the margins of a print by local treatment with a reducer (§, 585), or by rubbing with a wad of cotton wool impregnated with alcoTA.
Greenish Tones. Insufficient exposure.
Yellowish or Brownish Tones. Over-exposure, excess of bromide in the developer, or the use of an exhausted developer. As any bad colour in a print is not visible in non-actinic light, it is important to examine a few prints every now and then after fixation, by daylight or corrected light (lamps with blue bulbs, called daylight lamps) whilst the printing of a batch is in progress. In this way the colour can be seen, and any faults in the working conditions remedied forthwith. Prints of bad colour may be converted to a good black by chromium intensification (§§ 454 and 584), but as a rule such prints do not tone at all well.
Brown or Black Stains. The paper has been touched with fingers impregnated with hypo, or has been placed in a dish which has been used for fixing and not properly washed afterwards.
Yellow or Brownish Stain on the Margins and 1Vhites of the Image. These stains are caused by the oxidation products of the devel oper in a highly-oxidized developer or in a neutral fixing bath in which developer from previously-fixed prints has accumulated. I- They may also be caused by silver which has been reduced in a very finely-divided state by the same process which leads to the formation of dichroic fog (§ 433) on negatives or trans parencies, when too warm a developer or a developer which is too rich in sulphite is used. (particularly on gaslight papers), or by attempt ing to force the development of an under-exposed print.