1131. Time Development For The Correction Of Errors In Exposure

Time Development For The Correction Of Errors In Exposure. The preceding method of developing for a fixed time applies only to correctly exposed plates; in case of over-exposure the details may be found eaten away; in case of under-exposure the image may be under-developed and too dense. The following method overcomes this difficulty by allowing of regulating the duration of development according to the time of appearance of the first outlines of the image in a diluted developing solution. The dark-room light should be fitted with "Virida" papers, to permit of following the appearance of the image.

1132. To develop a 5x7 plate, place within handy reach two graduates of different sizes; one containing 3/4 oz. of Metoquinon Stock Solution, the other 2 1/4 ozs. of this same solution.

Pour into the developing tray:

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

3 ozs.

Metoquinon Stock Solution(Temperature 6o° F.)

1/4 oz.

Immerse the plate in this solution, starting at the same time to count seconds until the appearance of the outlines of the image (disregarding the sky). As soon as they appear, keep on counting and add to the developer: 3/4 oz. of Metoquinon Stock Solution if the image appears before 40 seconds, or 2 1/4 ozs. if the image appears after 40 seconds. Then continue developing for the total length of time given in the following table. The Lumiere people supply this table on transparent paper, which can be glued to the glass of the dark-room lantern, the light of which is strong enough to allow of reading clearly the directions:

1133.

Time of appearance of first outlines of Image disregarding sky.

Quantity of Meto-quinon Stock Solution to be added after image appears.

Total duration of development including time of appearance of image.

Seconds.

Ounces.

Minutes.

Seconds.

12

to

14

3/4

1

15

16

to

17

3/4

1

45

18

to

21

3/4

2

15

22

to

87

3/4

8

15

28

to

88

3/4

3

30

34

to

89

3/4

4

30

40

to

47

2 1/4

3

-

Over 47

2 1/4

4

-

1134. For a 4x5 or smaller plate use half of all the above quantities. The other operations - reversal of the image, and second development - should be carried on as explained before.

1135. The improvements made in the manufacture of Au-tochrome plates, which allow the use of this simplified method, do not interfere in any way with the use of the previous method of pyro development.