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BORAX DEVELOPER CHARACTERISTICS
135
Fig. 2. Relative silver content of developers after eight minute agitated development with the equivalent of 32 ft. of film per liter. The developing formula was sodium sulfite, varied; mptol. 2.5 g/1; borax, 5 g/1.
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Fig. 3. Eight minute developments with
Sodium sulfite, 75 g/1; metol, 2.5 g/1
borax, varied. Emul. 2568.
Curve Borax pH Fog
1 0 8.7 .03
2 2.5 8.7 .07
3 5 9.0 .07
4 10 9.1 .06
Borax
The borax appears to influence the development only through its effect on the alkalinity of the solution and hence its effect can be completely presented only in conjunction with other factors affecting the alkalinity of the developer. For the simple case, varying borax only, Fig. 3 shows the effect on the development for the 8 minute period chosen. Increasing the borax increases the alkalinity (represented by increasing pH) with a resultant increase in the activity of the developer. With the quantity of metol used in this series, there is little difference between development with 5 and 10 gm/1. of borax.
Reducers
In the first series of tests with its low borax concentration it soon became evident that the hydroquinone did little of the development. When the basic formula indicated for this series was mixed with the omission of metol, 16 minutes agitated development gave a barely perceptible density at the longest exposure given the test strip. Needless to say, such development is worthless. Mixing again, this time including the metol but omitting the hydroquinone produced a fairly satisfactory developer; one which produced densities which differed but very slightly from those produced by the complete formula.
In the case of the second series a similiar test was made, the results of which are presented in Fig. 4. Here the borax concentration is higher than in the previous case and the hydroquinone alone does develop noticeably, but still not enough to make a worth while developer by itself. Metol alone is very satisfactory and the densities differ but little from those produced with an additional 5 or 10 gm.