As a rule the photographer who follows the printed formula is the photographer who gets the best results. The development of Portrait or Commercial Film is very simple with either the tray or the tank method, but for convenience, economy and quality of results tank development is recommended.

The first users of films were big consumers and practically all of them used the tank method. The number of big consumers is constantly increasing, but smaller consumers are also being added to the list daily.

Many of these have made their beginning with tray development, and while tray development of films is more simple and convenient than tray development of plates, there is still greater convenience in tank development.

For either tray or tank development Pyro is recommended,experience having taught that the best results possible are produced by this developer. The peculiarity of Pyro, however, is that the color which gives the best printing quality in the negative is produced by a slight oxidation of the Pyro.

Tank Development Of Portrait Film StudioLightMagazine1918 84

FROM AN EASTMAN COMMERCIAL ORTHO FILM NEGATIVE

General Electric Co. Schenectady, N. Y.

If the necessary chemicals are added to a Pyro developer to give it good keeping quality, oxidation is retarded and the Pyro color is more or less eliminated. The three following formulas have been worked out for film and found to give the most satisfactory results.

The first is recommended for the excellent printing quality of negatives it will produce, which more than makes up for the trouble of preparing fresh solution for each batch of films that is developed.

The second developer gives medium warm tones. It will keep for two days and give negatives of excellent quality, but it must be discarded after two days' use. This developer will be found a great convenience by those photographers who have a fair number of negatives to develop each day and prefer a slightly warm-toned negative. It gives Pyro quality but has the advantage of reasonably good keeping quality.

The third developer has excellent keeping qualities when compounded carefully in accordance with instructions, and by the addition of a strengthening solution will keep for several weeks and produce excellent results. The negatives are of a blue tone. The keeping quality, however, depends entirely on the proper compounding of the formula.

The three formulas are as follows:

A. B. C. PYRO TANK FORMULA FOR WARM TONES

Stock Solution A

For 48 ozs. Solution

For 96 ozs.

Solution

Water......

16

ozs.

32

ozs.

Sodium Bisulphite or Potassium Metabisulphite .........

70

grs.

140

grs.

Pyro .................

1

oz.

2

ozs.

Potassium Bromide ....

8

grs.

16

grs.

Stock Solution D

Water......

16

ozs.

32

ozs.

C. K. Co. Sulphite of soda .......

1 3/4

ozs.

3 1/2

ozs.

(Or Hydrometer Test 55)

Stock Solution C

Water......

16

ozs.

32

ozs.

C. K. Co. Carbonate of Soda......

1 1/4

ozs.

2 1/2

ozs.

(Or Hydrometer Test 40)

For the one gallon tank take 5 1/2 ounces each of A, B and C and add water to make one gallon. For the 3 1/2 gallon tank take 19 1/4 ounces each of A, B and C, and add water to make 3 1/2 gallons. When large tanks are used, make up the large quantity of solution. Develop for about 12 minutes at a temperature of 65° F. Any scum that may form on the surface of the developer must be removed before developing films.

Tank Development Formula For Medium Warm Tones

Good only for two days use.

Pyro ....

1

OZ.

3 1/2

ozs.

C. K. Co. Sulphite of Soda

1 3/4

OZS.

6

ozs.

55

grs.

Bisulphite of Soda ....

1/4

oz.

385

grs.

C. K. Co. Carbonate of Soda

3/4

oz.

2

ozs.

275

grs.

Water to . . .

1

gal.

3 1/2

gals.

Tank Development Formula For Medium Warm Tones StudioLightMagazine1918 86

FROM AN EASTMAN PORTRAIT FILM NEGATIVE

The B. F. Goodrich Rubber Co. Akron, Ohio

Tank Development Formula For Medium Warm Tones StudioLightMagazine1918 88

FROM AN EASTMAN COMMERCIAL ORTHO FILM NEGATIVE

The B. F. Goodrich Rubber Co. Akron, Ohio

Tank Development Formula For Medium Warm Tones StudioLightMagazine1918 90

FROM AN EASTMAN PORTRAIT FILM NEGATIVE

General Electric Co. Schenectady, N. Y.

The following instructions must be strictly followed, as the keeping qualities of this developer depend entirely upon the method of preparation.

Dissolve the Sulphite first, in three quarts of hot but not boiling water. When dissolved, add the Bisulphite and then boil the solution for five minutes. Cool to about 70° Fahr. and add the Pyro. Dissolve the Carbonate in one pint of warm water. Pour these two solutions into the tank and make up to one gallon with water, or three and a half gallons, as required. Develop for about 13 minutes at a temperature of 65° F.

This developer gives a medium warm tone and will keep well for two days. The color progresses with the age of the developer. Any scum on the surface must be removed before developing films. It must be discarded after two days.

Tank Development Formula For Blue Toned Negatives

The following Pyro-Soda formula, based upon the use of a neutral sulphite obtained by the combination of Sulphite of Soda and Sodium Bisulphite, gives excellent results:

Pyro...........

1

ozs.

4

ozs.

85

grs.

80

grs.

C. K. Co. Sulphite of Soda

6

ozs.

22

ozs.

175

grs.

175

grs.

Sodium Bisulphite . . ,

1 1/2

ozs.

5 1/4

ozs.

C. K. Co. Carbonate of Soda

2

ozs.

7

ozs.

Potassium Iodide . . . .

5

grs.

18

grs.

Water up to .......

1

gal.

3 1/2

gal.

The following instructions must be strictly followed, as the keeping qualities of this developer depend entirely upon the method of preparation.

Dissolve the Sulphite first, in three quarts of hot but not boiling water. When dissolved, add the Bisulphite and then boil the solution for five minutes. Cool to about 70° Fahr. and add the Pyro. Dissolve the Carbonate in one pint of warm water, then add the Iodide. Pour these two solutions into the tank and make up to one gallon or three and one-half gallons with water.

The most satisfactory temperature for developing is 65° Fahr. The so • lution should not be used below 60°.When the developer is first made and used, the developing time at 65° F. is about 18 minutes.

This made-up developing solution may be kept in the Developing Box, but when not in use, it should be covered to prevent evaporation and deterioration. A floating cover of wood made to fit inside the top of the box is recommended.

After the developer has been used for several batches of films, it will be necessary to strengthen it with the addition of each new bath. The strengthening solution is made by dissolving the chemicals named in the following formula and using exactly the same method for preparing it, as when preparing the first developer.

STRENGTHENING BATH FORMULA

Pyro .........

1/4

oz.

C. K. Co. Sulphite of soda.........

l

oz.

and

150

grs.

Sodium Bisulphite

150

grs.

C. K. Co. Carbonate of Soda . . . .

3

ozs.

and

50

grs.

Potassium Iodide . .

4

grs.

Water up to . . . .

60

ozs.

Add this strengthener to the developing solution in the tank as needed, to keep up the developing strength of the solution.

Get the BEST result, use EASTMAN PROFESSIONAL FILM

Tank Development Formula For Blue Toned Negatives StudioLightMagazine1918 92

FROM AN EASTMAN COMMERCIAL ORTHO FILM NEGATIVE

General Electric Co. Schenectady, N. Y.