[rollei_list] Re: Rolleiflex traveling
- From: Jerry Lehrer <glehrer@xxxxxxxxxx>
- To: rollei_list@xxxxxxxxxxxxx
- Date: Wed, 05 Oct 2011 16:36:40 -0700
Richard,
Don't you mean DK-20, which was known back then to have a sequestering
agent? I found that D-25 or D-"24"
beat it out.
I just looked at some of my 60 year old negatives (Rollei and Leica
developed in Edwal 12 and Edwal 20. To
me, those were the best developers for the films of those times (I used
Plus-X film, mostly)
JERRY
On 10/5/2011 3:45 PM, Richard Knoppow wrote:
----- Original Message ----- From: "william schillereff"
<pastorbill6@xxxxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, October 05, 2011 10:34 AM
Subject: [rollei_list] Re: Rolleiflex traveling
Is there anyplace to find these formula's so one can try to mimic them
with chemical and scales? I have finally found a place selling the bulk
chemicals and I am highly tempted to try making my own soup again.
I have never seen a published formula for Microdol-X or Perceptol
but the information must be around somewhere. About the only technical
information I've seen on this type of developer is in Grant Haist's
old book. Its something like D-20 but with about 20 grams per liter of
sodium chloride added. The X in Microdol-X evidently is a silver
sequestering substance to eliminate dichroic fog which can be a
problem with extra-fine-grain developers. I have no idea of what this
is because it does not appear on the MSDS. Kodak originally came out
with just plain Microdol but changed it to Microdol-X after about a
year. I think the difference was the addition of this anti-fogging agent.
I don't know the mechanism by which the salt works but think it is
not the same as the solvent action of developers like D-25. I once
posted that the finer grain of D-25 over D-20 was due to the lower
activity and thus longer application of the solvent action but Ryuji
Suzuki posted back suggesting this was not the case. However, he did
not give an alternative explanation, so I am left in the dark about this.
FWIW, the patents for Xtol give pretty clear data on how to make
it. The only drawback is that some of the ingredients are not readily
available.
BTW, avoid iodized salt since the iodine is photographically
active. Also much table salt has other things in it to make it
free-flowing when its humid. I don't know if these are detremental to
its photographic functions. Plain fairly chemically pure salt is
available in many places as kosher salt.
--
Richard Knoppow
Los Angeles
WB6KBL
dickburk@xxxxxxxxxxxxx
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