FotoDave@aol.com
Tue, 25 May 1999 20:22:44 -0400 (EDT)
Sandy and all,
I probably should explain (should have explained) myself better. I did not
mean to say that if you have a formula and you simply double or half the
amount, you would get the same result. What I really meant is if one is
calibrating the system, s/he should be able to get very similar result.
> For the past several months I have been
> working on an experimental pyrocatechin/metol developer with sodium
> carbonate as the accelerator.
Interestingly, I did similar experiments but with metol only for compensating
effect, and ....
> Working from concentrated A
> (Metol+Pyrocatechin) and B (10% sodium carbonate) solutions the film tests
> that I completed showed a signicant difference in developer activity (as
> measured by develolpment to a specific CI) between the following working
> dilution: 1) 1:2:100, 2) 1:5:100 and 3) 1:10:100
yes the concentration of carbonate would affect the activity, but when 2
dilutions are calibrated to give the same contrast index, the give similar
curves, but of course the one with less carbonate shows more compensating
effect, which I also mentioned in the post.
Also, I mentioned that the buffer capacity is affected especially in high
dilution. In your example, the carbonate is 10%, so there is only 100 gr. /
liter. In working solution, there is another about 100x dilution, so there is
only 1 gr. of carbonate / liter, thus the concentration matters more.
I was talking about more or less "normal" developer, basically.
Sorry if it was unclear or misleading.
Dave S
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