Richard Sullivan (richsul@earthlink.net)
Fri, 07 May 1999 15:05:01 -0600
Jeff,
You are probably right on the formula. During the development phase I
calculated what I assumed the formula would be and my notes show that is
what you arrived at. I then tinkered with variations and arrived
experimentally at what is the published formula.
According to Ware, excess chloride has a restraining effect and is assumed
to raise contrast and slow down the speed. Your results with less chloride
show more speed and more contrast. It may well be that the increase in Pd
will reduce the tendency to milk over. On the practical side, if you were
to see some of Carl's prints done with the published formula you hard
pressed to see room for any improvement.
I am currently in the midst of moving to a new house but as soon as that
panic is over I am looking eagerly forward to trying your revised formula.
I suspect you may be right in your observations that it produces a better
dmax.
--Dick Sullivan
At 03:43 PM 5/7/99 -0400, you wrote:
>I seem to recall someone posting a question a few days ago concerning a
>milky appearance of some Zia prints; this may help address that issue.
>
>I tried out some Ziatype at an ambient 70 % humidity just for the
>halibut and found some interesting results. On two of two occasions the
>modified formula as posted earlier produced fine prints. Well low and
>behold, the published formula produced prints with milky splotches on
>them. These splotches certainly looked like the result of a weak
>chemistry.
>
>This certainly is consistent with my other observations, although I
>don't know why it decided to manifest itself at the higher humidity.
>
>As an aside: Since I have just built a new darkroom, knowing I would be
>doing the Ziatype variation, I tried to employ some control over
>humidity. I have two dehumidifiers and a sonic mister and a heat
>exchanger working with the ventilation system. This seems to give some
>control. Although when dryer weather rolls around I expect I will have
>to add another mister. Part of the plan is haveing the air enter the
>room near the heater, dehumidifiers, and mister (as far as can be from
>the sink) and then leaving the room from pickups along the back of the
>sink.
>
>--
>Jeffrey D. Mathias
>http://home.att.net/~jeffrey.d.mathias/
505-474-0890 FAX 505-474-2857
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