This is not a Japanese war map, neither is it a Florentine mosaic nor a diagram of the present political situation. It is a plain case of reticulation or frilling of the emulsion of a dry plate. Our illustration is an excellent example of a very bad case of this somewhat common difficulty.

Frilling or reticulation of the emulsion often occurs to a greater or less extent when handling plates in hot weather if solutions are too warm. Most photographers are troubled at times on account of frilling, softening, lifting or slipping of the emulsion and are no doubt sometimes unable to account for the very peculiar appearance of their negatives. These various phenomena of the same trouble, and of which the above cut illustrates only one phase, are not infrequent occurrences, and while causing infinite trouble at times are nevertheless very simple things to explain and avoid, once the real cause is understood.

During warm weather when the temperature of the work rooms and the various solutions are liable to become high, plate emulsions have a tendency to become swelled and softened. This is also liable to occur when the fixing bath becomes overcharged with alkali from the developer. The effect is to loosen the emulsion from the glass support and as the gelatine expands it puckers and forms more or less minute wrinkles over the entire surface and these arrange themselves with a certain degree of regularity. In extreme cases the emulsion slips from the glass entirely. In such cases the expansion of the film leaves sections of clear glass and the lines of reticulation are broad and far apart.

There are various ways in which this effect can be produced. It sometimes occurs under certain conditions when intensifying with mercury and is also purposely brought about for certain photomechanical processes by the use of chemicals of an astringent nature acting on a softened emulsion, but these causes are somewhat remote from the general everyday practice of photography. It is not necessary to deal with these causes at this time.

Another species of frilling while not producing the effect of reticulation is nevertheless of a similar nature and may be of interest to mention. This is a partial melting or softening of the emulsion during drying and occurs when allowing plates to dry over night in a close, damp but warm atmosphere. This causes the emulsion to separate and to have a coarse grain. It also thickens the negatives and clogs the high lights and half tones.

There is no remedy for reticulation, softening, frilling and other similar troubles, once they show up. The old adage, "An ounce of prevention is worth a pound of cure," is nowhere so true as in photography.

With well ventilated workrooms, solutions kept fresh and at the proper temperature and with an electric fan for drying, these peculiar hot weather troubles, from which no one is entirely free, can in a large measure be avoided.

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