[pure-silver] Re: TMAX grain - developer modification?
- From: "John Black" <jblack@xxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Mon, 11 Oct 2004 11:37:39 -0400
>
> > Well, without the aid of an electron microcope one can not
> > be sure but certainly Tri-X seems to have this problem when
> > developed in very alkaline developers like Rodinal. Of
> > course, you are right, I am assuming text book research
> > describes phemomonon that occur in actual practice.
Ryuji and I have discussed this putative phenomenon of "grain clumping" at
length off list in the past. I don't have access to an EM scope yet but
hope to in the future to look at precisely this effect. There is no doubt
that precieved grain and pH of developer are linked. The higher the pH, the
greater the activity and precieved grain. This is why Xtol stock is adjusted
to pH 8.3.
I haven't taken the Ph of Rodial because I have none, but I have checked
others and have found:
TMax developer (1+4 stock) pH 8.45
DD-X (1+4 stock) pH 8.70
HC110 "B" pH 9.00
Xtol stock pH 8.20
Xtol 1+3 pH 8.50
HC110B is almost as aggressive as Rodinal and produces grain comperable to
Gainer's formulations (too grainy in 35mm for my tastes).
Films designed to be push processed, P3200/Delta 3200, require a higher pH
developer and the shadows just arn't there with a low pH product such as
Xtol. The 3200 films are actually 800 speed films in Xtol but can be used
at 1600-3200 with DDX or HC110B (although with more pronounced grain).
> Last time I pointed out that Trivelli and others were studying grain
> morphology and photographic properties of emulsions and he found no
> instance of grain clumping despite very early reports on such a
> phenomenon from 1910's or 1920's. I was wondering if you had any
> further evidence that requires to change the view.
My microscopic observations of grain in negatives show that the coarse
grained images have 2 populations of particles visible at about 100X. One
population is small, fine and very uniform and comprises the majority of the
image. The other population is made up of random, large discrete points of
great density that seem to be uniformly distributed throughout the image.
Fine grained negatives lack these large, dense bodies and are entirely made
up of the fine, uniform grains. The size and density of the small particles
seems to be dependant on the type of film (origin and brand).
I too find the new Tri-X in the right developer to be finer grained than
TMY.
JB
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