[rollei_list] Re: Limit of Rolleicord Triotar
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <rollei_list@xxxxxxxxxxxxx>
- Date: Wed, 11 Oct 2006 20:33:12 -0700
----- Original Message -----
From: "Richard Sintchak" <rich815@xxxxxxxxx>
To: <rollei_list@xxxxxxxxxxxxx>
Sent: Wednesday, October 11, 2006 5:40 PM
Subject: [rollei_list] Re: Limit of Rolleicord Triotar
On 10/11/06, Richard Knoppow <dickburk@xxxxxxxxxxxxx>
wrote:
".....developed in full strength Microdol-X or Perceptol
(they are
identical)........."
How sure are you about this? The late Barry Thornton (who
was no slouch
when it came to experience in developers, even creating a
few of his own)
compares these two in his books (Elements, and Edge of
Darkness). I
specifically remember him discussing at a point in his
evolution of
developer experience about Microdol-X and then later how
it differed and was
surpassed in some respects what he liked in a developer by
Perceptol. I
think he even discussed some of the differences in the
chemical content and
properties of each and how this effected results. I'll
find the reference
later tonight after I get home.
Richard S.
The MSDS show virtually identical contents. There are some
ingredients that do not appear in the MSDS and one has to
guess about them. The X in Microdol-X indicates an improved
version, there was a plain Microdol at one time. Grant Haist
speculates this is a silver sequestering agent, perhaps a
mercaptan, added to eliminate dichroic fog and possibly
reduce the amount of physical development. My experience
with both developers is that they are essentially identical
in results.
BTW, there was an erroneous MSDS for Perceptol for
several years. It listed Sodium Bromide instead of Sodium
Chloride. I wrote to Ilford about this, I got an e-mail back
appologizing and confirming the ingredient is Sodium
Chloride. Shortly thereafter a corrected MSDS was posted.
Chloride is a fine grain agent. There appears to be very
little in the literature about it or how it works. Haist
mentions it and cites an article in a magazine (I will have
to look it up because I don't remember) which he states is
the only source of data. There may be a patent but I've
never seen it cited.
Microdol and Perceptol are similar to the D-23/D-25
family. They consist of Metol as the sole developing agent,
akalized with Sodium Sulfite (D-23). D-25 obtains its extra
fine grain property by buffering D-23 to neutral pH with
Sodium Bisulfite. Metol is unusual in developing agents in
that it will develop at neutral, or even slightly acid pH.
Of course, it has very low activity under that condition.
Microdol and Perceptol are similar to D-23 but instead of
being buffered to neutral they have a large quantity of
Sodium Chloride added. Again, I don't know the chemistry of
the chloride and how it produces extra fine grain. Both D-25
and Microdol loose their extra fine grain property when
diluted. At 1:3 they have similar grain and film speed to
D-76 but become high acutance developers. When used full
strength there is a loss of film speed of about 3/4 stop.
When 100T-Max is developed in full strength Microdol or
Perceptol its grain is similar to Technical Pan and the
resolution is nearly as great. I shoot it at about EI-60.
The fine grain characteristic is such that the tonal quality
begins to have the smoothness of a larger format. I have not
yet tried this on 120 T-Max but have a roll nearly ready to
develop now. If the difference is the same the negatives
should be similar to 4x5 in grain and detail.
Thornton, unfortunately, can not defend himself,
otherwise I suspect he would be taking part in one or more
of these lists. I have no idea of his sources of
information. Its possible the actual formulations may differ
especially insofar as whatever sequestering agents or other
special purpose additives are used.
I am currently using Perceptol and have no complaints
about it. In the past I used mostly Microdol-X, the change
this time was simply availability. BTW, I have also found
that this type of developer (whichever brand) also gives me
very pleasing tone rendition.
FWIW, for a long time I was using Microdol-X 1:1. This
was originaly an error but I liked the results and it was
economical so I continued.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
---
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