Sulphite of Soda is used as a preservative and prevents the developer from decomposing rapidly and becoming discolored.

Carbonate of Soda is used to open the pores of the emulsion and allow the developer to act freely and evenly.

Bromide of Potash is used to keep the whites clear, and is also important in controlling tone. The more Bromide used the more olive will be the tone of the resulting print. Without Bromide, or with too little Bromide, grayish, fogged prints will be obtained. Be sure to use a Saturated Solution of Bromide in the developer.

1039b. Modifying Developer to Control Contrast. - Developer mixed according to formula cannot be improved on for the general run of work.

Increasing the amount of hydroquinon and reducing the amount of metol will increase the brilliancy or contrast of the prints to a certain extent.

Increasing the amount of carbonate will cause developer to work more vigorously. and also tend to produce black tones without olive. Reducing the amount of carbonate will cause developer to work slower and will produce softer results.

It will thus be seen that to produce more contrast in prints the hydroquinon should be increased, also the carbonate, and as this will tend to make developer work more rapidly, the bromide should be increased so as to enable the operator to control the development of the print.

To produce less contrast in prints use double the amount of metol, half the amount of hydroquinon and half the amount of carbonate called for in the regular formula.

If developer discolors rapidly when being used, it will indicate weak or old sulphite of soda, which is the preservative. Use fresh sulphite of good quality.

Bromide of potash plays an important part in the developer. We cannot give the exact amount necessary to use under all conditions. Some of the conditions that make it necessary to vary the amount of bromide are as follows:

Water used in mixing developer.

Quality of soda used.

Age of paper, etc.

Old paper will generally require more bromide than fresh.

Enough bromide should be used to keep the prints from fogging in the developer. If only enough to do this is used, the tone of the prints will be cold or blue-black.

A slight increase will give a better black.

With further increase comes the more desirable warm or olive-black tone.

The formula which follows is based on the preceding principles. It will produce good prints from negatives that are inclined to be strong, and also from normal negatives for low tone effects where contrast or snap is not desirable.

It will give good, rich prints, but will search up into the highest lights for every gradation or half-tone. This developer works slower than the normal developer, on account of the reduced amount of accelerator (carbonate of soda), and to avoid flatness prints should be allowed more time to develop. Following is the formula:

Water................................

40 grs.

Metol................................

20 grs.

Sulphite of Soda (dry)............................

1 oz.

Hydroquinon........................................

40 grs.

Carbonate of Soda (dry).....................................

90 grs.

When ready to develop add one drop of a saturated solution of bromide to each two ounces of developer.

In hot weather you may find it advisable to reduce the amount of carbonate in your regular developer, even though you don't want a soft print. Too much carbonate in the developer during the summer months may make your prints too contrasty, as the developer is apt to work very vigorously and quickly unless the temperature is kept down to normal; 650 to 700 Fahr. is normal.

1039c Controlling Tone and General Quality by Exposure and Development. - All Artura papers possess considerable latitude of exposure. By that we mean the exposures may vary some without changing the tone or general quality of the prints.

Following are effects produced by different exposures, using the same developer throughout:

Extreme Under-exposure and forced development will cause prints to be flat and weak, cold or blue in tone, and lacking detail in the high-lights.

The whites in a forced print are also apt to be grayish or discolored and stained.

Slight Under-exposure will produce prints of fairly good quality, but cold in tone.

Normal Exposure will of course produce the best effects. Normally exposed prints will develop to the desired depth freely without forcing the development.

Slight Over-exposure will increase the contrast of the print slightly. This rule can be used to advantage on negatives that lack snap or brilliance. For this reason slight over-exposure should be avoided when printing from harsh negatives.

Extreme Over-exposure will cause prints to develop rapidly and to be flat and muddy in general appearance.

1039d. Temperature of Solutions. - Hot weather will not cause Artura prints to blister, frill, stain or to become soft and sticky.

The proper temperature for all solutions is 650 Fahr., and if convenient they should be kept at about that temperature.