The Dictionary Of Photography

A True Historic Record Of The Art & Practice Of Photography 100 Years Ago.

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Bromide Paper
the image is also a dull grey, and contains no rich blacks. The obvious remedy is to shorten the exposure, but the over-exposed print may also be improved by a process of intensification.
The exposure has been under-estimated, or the enlargement is under-exposed. An under-exposed bromide print is full of ex-treme contrast, the shadows black and heavy, and the high lights wanting in detail, and showing bare patches of paper. Increas-ing the exposure is the only remedy, and an under-exposed print had better be consigned to the residue box rather than shown.
The print is fiat, and wanting in contrasts, and does not even show white paper under the pins or bands which hold it on the easel. This is probably due to stray actinic light. The room in which the enlargement is made, and the lantern, if such be used, should be examined for stray leakage. Such a print may be improved by slightly reducing, washing, thoroughly converting the image into chloride of silver, and redeveloping.
Faults due to the Developer.
The print during development becomes covered with a sandy yellow deposit. This may be caused, first, by too much acid in the developer; second, by want of acid in the developer ; third, by using too much ferrous sulphate; fourth, by using too little oxalate solution. The remedy for the second cause is the addi-tion of some acid to the developer, both to the oxalate and iron solutions. Ferrous oxalate, formed by the addition of ferrous sulphate solution, is soluble only in excess of oxalate of potash ; therefore, if too much iron solution be added, some of the ferrous oxalate will be precipitated. In such a case pour off the de-veloper, and add more oxalate solution and a grain or two of oxalic acid. If the oxalate solution is allowed to sink to too low a temperature some of the oxalate will crystallise out, and the solution thus be weakened. The remedy is obvious.
The print during development becomes covered with a white chalky deposit. This deposit, which is oxalate of lime, is caused by using ordinary tap or hard water for soaking the print or for diluting the developer. The remedy is obviously the use of dis-tilled water or clean rain water. When, however, such a deposit occurs, the only plan is to continue the development till the print is done enough, and then remove the deposit by a weak hydro-chloric acid or sulphuric acid bath.