Re: Developing sheet film in open-ended PVC tubes

From: Argon3@aol.com
Subject: Re: Developing sheet film in open-ended PVC tubes
Date: Wed, 31 Mar 2004 17:45:59 -0500 (EST)

> One of the points made earlier, if I recall, was to use this
> procedure to do a development with minimal agitation in order to
> enhance the adjacency effect.

As you described, accutance enhancement through adjacency effect is
relatively easy to obtain without uneven development.

One major claim made by advocates of development with minimum
agitation is reduction of highlight contrast. I find this effect
almost always comes with uneven development, and the result is not
predictable and reliable either.

Coming back to adjacency effect,

> This was based on the theory that one should use a dilute
> solution of developer, in this case D-76 1:1 and use twice the volume of
> developer as would customarily be used for the given amount of film;

There are a lot more factors described in literature.

Active hydroquinone reduces or eliminates adjacency effect. D-19 is
often used with or without dilution where adjacency effect is
undesirable, because its high hydroquinone content practically
eliminates the effect. The reason is that development reaction product
of hydroquinone (or pyrogallol or catechol, for this matter)
effectively enhances the development of the adjacent area. These
products quickly react with sulfite ion, but when this happens, it
increases the alkalinity of the solution nearby, again enhancing the
development. For adjacency effect, you want the opposite effect -- the
development reaction products to be effective development inhibitors
and development reaction should release protons.

Dilute metol only, metol-ascorbate or phenidone-ascorbate developer
gives excellent adjacency effect.

But the dilution, pH, temperature and other factors should be adjusted
so that the rate of development is rapid. If development is slow,
reaction products have more time to diffuse out, and more fresh agents
diffuse in from the bulk solution, before adjacency effect kicks in.

--
Ryuji Suzuki
"All the truth in the world adds up to one big lie." (Bob Dylan 2000)