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The Barnet Book of Photography A Collection of Practical Articles

Failures in working the carbon process are caused


FAILURES AND DEFECTS: THEIR CAUSES AND CURE.

As a rule, failures in working the carbon process are caused, as in most other cases of failure, by imperfect _knowledge of the substances and nature of the ingredients used in the process_. Before going into further detail, it may be as well to point out that a great deal of misunderstanding has been caused, by writers on this subject--that may be fairly termed "blind leaders of the blind." With only slight knowledge of the subject they have misled beginners by assuring them that the process is simplicity itself, in fact the most simple photographic printing process extant. Up to a certain point, and to that certain point only, is such description true. There are no subtle chemical combinations, no mixing and maturing of toning or other solutions. But--and in this case there is great virtue in the _but_--the greatest care is not only required, it is absolutely demanded, in manipulation. A carbon print from start to finish is probably subject to more chances of injury than any other form of print in existence. When this fact has been fully grasped by the novice, and he has been thoroughly prepared for the difficulties before him, the rest is plain sailing. Care, and care only; nothing beyond. He who wishes to succeed in carbon work must pay infinite attention to every small matter of detail as far as such detail relates to manipulation, otherwise he will only succeed in achieving failure.

justify;"> FRILLING AND RETICULATIONS.

Frilly reticulations are generally caused by over-soaking the tissue before development, or failing to provide protection of the clear portions of the margin of the negative by a safe edge.

SPOTS ON THE FINISHED PRINT.

Spots are generally caused by solid particles of grit or other impurities being allowed to find their way into the water in the process of development, or, as in the case of certain peculiar circular spots that often deface the carbon print, such spots are caused by small fragments of tissue broken from the edges in cutting, which, being of the same colour as the prepared surface of the tissue and exceedingly small, often escape notice. They adhere most tenaciously to the surface of the tissue, and if not removed before the print is mounted upon its temporary or final support, cause the mischief referred to; being confined between two surfaces they cannot escape, but are dissolved by the water used in developing the print, swell and make a circular patch, often greatly injuring the picture.

Spots of a different character are produced in quite an opposite direction. Instead of being black they are light, in groups each spot having a dark rim on the outside. They generally occur in under-exposed prints, and are formed by fine particles of air imprisoned between the coating of gelatine and the paper support. When the tissue is mounted for development and placed in warm water, the fine particles of air swell, and not being able to escape from between the surfaces, impress themselves into the yielding portions of the printed tissue and make the marks above referred to, unless the printing has been deep enough to allow of their removal before development is completed.

CAUSE OF FAILURES IN THE SECOND TRANSFER.

Other causes of failure refer particularly to prints by double transfer, either to paper, opal, ivory, canvas or wood panel or any similar surfaces.


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