Mr. Reed, with other equally broad minded photographers of Wichita, have a local photographic society, get together in the most friendly spirit of helpfulness to one another and, no doubt, profit by their friendly relations.

Mr. Reed is an excellent workman, uses only the best of materials and has found that the quality of work so produced is sufficiently appreciated to bring a price in proportion.

Our cover illustration as well as several of those on our inside pages are excellent examples of Mr. Reed's work.

Our Illustrations StudioLightMagazine1918 164

FROM AN ARTURA IRIS PRINT

By Fred H. Reed Wichita, Kans.

Bright Red Poppies With Black Centers

Orthochromatic Plate with filter. Result is poor because plate is not sensitive to red.

Our Illustrations StudioLightMagazine1918 170

Wratten Panchromatic Plate without filter Result is good because this plate is so sensitive to red.

The forming of a pattern or design by reticulation has been used in some photo-mechanical processes, such as the collotype, and for the production of irregular grained half-tone screens, but such processes are not of special interest to photographers.

An understanding of the conditions affecting and determining reticulation will be best understood if we first consider a few facts on the normal swelling and shrinking of photographic gelatine film, which takes place in its treatment and use.

There are two things to consider : the change of mass or bulk, and the change of shape. Any piece of gelatine placed in water within a temperature range of from 32° F. to 68° F., swells, at first, rapidly, then more slowly, and finally reaches a limit.

The limit of swelling depends upon the temperature, the character of the gelatine, and the presence of foreign substances in the water. Acid and alkali, in particular, have a great influence upon the swelling.

Gelatine should, theoretically, swell or shrink uniformly without change of shape, only altering its mass or bulk. This would be true if it could be dried very slowly so that drying would proceed at the same rate in all parts of the mass.

This is not possible in practice, however, as an emulsion placed on glass dries more rapidly on the surface than in the interior, producing stresses and distortion. The gelatine emulsion coated on a glass or film support is also firmly attached to it, so that one side is eliminated as regards drying.

The gelatine cannot spread off the plate so that its swelling or shrinkage is limited to one direction, viz., perpendicular to the plane of the support. Under normal conditions a gelatine film can be repeatedly swollen and dried without injury, but as the swelling parallel with the surface, which would remove the gelatine from the plate, is prevented by adhesion to a rigid support, the lateral strain must be compensated by the perpendicular swelling.

Suppose, however, that there is excessive swelling and shrinking, either successively or simultaneously, then the gelatine would be strained beyond its limit, causing either total or partial reaction. In the former case, the result would be that of frilling or the film entirely leaving its support, while in the latter, the strain not being uniform, we get a local puckering or folding. This is the common form of reticulation. The two effects are shown in Fig. 4, the shaded section representing the glass or film support.

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ORDINARY PLATE The colors are incorrectly rendered

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PANCHROMATIC PLATE K3 FILTER Notice the correct rendering of the entire design on each of the cards

Our Illustrations StudioLightMagazine1918 173Fig. 4

Fig. 4

The next thing is to determine the chemistry of the process which causes the excess swelling pressure and the localized arrest of this.

Reticulation was produced as follows: An ordinary plate was flashed, developed in a standard pyro-soda developer for 4 minutes at 80° F., then rinsed and fixed in a standard hypo-bisulphite fixing bath at 80° F, Reticulation was then found to depend upon the temperature of the wash water as follows:

Temperature

Reticulation

70° F.

None

80° F.

None

90° F.

Faint

100° F.

Strong

Instead of water, stronger and more definite results were obtained by an after-treatment with the following solution:

95% Ethyl Alcohol ......... 50 c.c.

5% Formaldehyde ......... 40 c.c.

Water ..................... 110 c.c.

In this case the following factors may have played a part:

(1) Prehardened gelatine in the emulsion.

(2) Tanning agents in the developer.

(3) Excess swelling pressure in hot developer, etc., and particularly in washing.

That reticulation can be produced by the combined action of a swelling or softening agent, and a hardening or anti-swelling agent to restrain this, is shown by the production of reticulation by the following combinations:

Hardening Agent

Softening Agent

(l) Tannic Acid

Acetic Acid

(2) Quinone

Acetic Acid

(3) Chromic Acid

Hot Water

(3) Mercuric Iodide

Potassium Iodide

All of these combinations produce reticulation.

The conclusion to be drawn from these experiments, is that the most common form of reticu-tion is due to the tanning agents in the developer, and the hardening agents in the fixing bath not hardening the gelatine uniformly because of the presence of alkali or acid in connection with heat, all of which have a softening or swelling action. Consequently, some portions of the gelatine shrink, while other portions swell, and as there is not sufficient room for the swelled or puckered portions to dry down to the film's original thickness, ridges are formed with intervening valleys, making a distinct design.

The design in reticulation is much more apparent where there is a developed image, than in the

Photomicrograph Of A Flea

Photomicrograph Of A Flea

Panchromatic Plate and Red Filter

Panchromatic Plate and Red Filter.

Our Illustrations StudioLightMagazine1918 177

Fig. 5

Our Illustrations StudioLightMagazine1918 178

Fig. 6

Ordinary plate without filter. The reddish brown body is too dark. The over-correction of the red filter gives the desired result more transparent parts of a negative. There is an apparent migration of the silver particles, making the ridges denser, while the valleys are less dense or quite clear. This is similar to the effect (a dark ring) produced when a drop of water is allowed to remain on a negative until it dries. The tension in drying softens the gelatine and forces the silver particles to the circular boundary of the spot.

It is quite possible that the action of some developers in producing grain in negatives is really a form of incipient reticulation. The original grain of the plate is coarsened in development by a clumping together of the original grains, which is noticeable and objectionable in enlarging. It is believed that nuclei are formed by the developed silver particles, which have a tendency to gather to them the finely divided reaction products of development which have tanning or coagulating properties.

Considering the great change in the swelling of an emulsion in passing from an alkaline developer to an acid hypo, it is quite likely that any sub-microscopic reticulation would be further developed, and the grain of the silver image again coarsened. Further experiments are hoped to bring to light more information on this subject.

By adhering strictly to the use of the formulas recommended by the manufacturer, using fresh solutions, and keeping them cool, such troubles will be avoided and the best results always secured.

Figures 5 and 6 are photo-michrographs of examples of reticulation. The illumination was vertical, the enlargement about sixty diameters.

Our Illustrations StudioLightMagazine1918 179

By J. M. Belt. Standard Orthonon Plate