PaRodinal is a very good concotion, DonaldQualls made a very good brew
and his recipe is in digitaltruth
From: `Richard Knoppow <dickburk@xxxxxxxxxxxxx>
To: pure-silver@xxxxxxxxxxxxx
Sent: Friday, April 17, 2015 10:35 PM
Subject: [pure-silver] Re: Rodinal
More interesting hits on Rodinal:
http://unblinkingeye.com/Articles/Rodinal/rodinal.html
Rodinal using Tylenol
http://www.drfrankenfilm.com/diy-rodinal/4575179217
Yet another version:
http://www.digitaltruth.com/data/rodinal.php
Note that the Wikepedia article on Rodinal claims its sharpness is due
to not having a silver solvent. This is nonsense, silver solvents, like
sulfites, do not affect sharpness or resolution of the image. Their action is
on a much smaller scale. Rodinal when diluted tends to produce edge effects as
I mentioned before. Sulfite does tend to reduce edge effects because it tends
to change the reaction products of the developer. Some sulfite is necessary to
prevent the developer from oxidizing rapidly and also to prevent staining of
the emulsion from the reaction products of some developing agents. Where
staining is desired, as with some pyro formulas, the amount of sulfite or other
preservative must be limited. There ARE non-staining pyro developers. When
pyro was very popular for use for motion picture negative development the stain
was considered undesirable and a number of formulas were worked out to
eliminate it.
Also, the first site I linked mentions the use of eosine. None of the
other sites do. I am not sure what function eosine would have in a developer
but I think the formulas using potassium hydroxide, and potassium metabisulfite
are probably pretty close to the original AGFA formula. BTW, AGFA made a lot
of potassium as by-products of its general chemical manufacturing so it was
very cheap for them to use potassium compounds.
On 4/17/2015 5:49 PM, Janet Gable Cull wrote:
Thank you, all!
On Fri, Apr 17, 2015 at 4:34 PM, Eddy Willems <eddy@xxxxxxxxxxx> wrote:
TRI-X ISO 400 20° C 1+50 8'30
1' prewash
best regards
Gary Marklund schreef op 17/04/15 om 22:17:
OK, You have my attention. I just went into the darkroom and I have two
bottles of real Rodinal. A 500ml bottle that was opened (and probably used
once) in 2005. I shook the bottle and it gurgled like it was new. The other
bottle is a 125ml bottle that has never been opened, still has original Rodinal
notes folded over the top of the boxed bottle).
My M6 has been screaming "Feed Me!" for some time. Like Janet, I'm interested
in using it with Tri-X (also Ilford delta 400).
Comments and E.I. and development times more than welcome.
Thanks, Gary
On Fri, Apr 17, 2015 at 1:08 PM, Gary Marklund <garymarklund@xxxxxxxxx> wrote:
OK, You have my attention. I just went into the darkroom and I have two
bottles of real Rodinal. A 500ml bottle that was opened (and probably used
once) in 2005. I shook the bottle and it gurgled like it was new. The other
bottle is a 125ml bottle that has never been opened, still has original Rodinal
notes folded over the top of the boxed bottle).
My M6 has been screaming "Feed Me!" for some time. Like Janet, I'm interested
in using it with Tri-X (also Ilford delta 400).
Comments and E.I. and development times more than welcome.
Thanks, Gary
On Fri, Apr 17, 2015 at 12:45 PM, `Richard Knoppow <dickburk@xxxxxxxxxxxxx>
wrote:
On 4/17/2015 12:01 PM, Janet Gable Cull wrote:
Richard, will you describe "edge effect"? I wonder if that's what I observed
in my friends scans that I like. I wonder how and why it would do that? Does
it somehow perceive the light and dark of an image, and treat them differently?
Edge effects, sometimes called border effects, are variations in
development at the border of a high and low density area. The nature of the
effect depends on the developer, specifically on whether its reaction products
suppress or enhance development. The effects are very localized because they
are due to diffusion of the developer reaction products in the emulsion. The
usual effect is to increase the contrast at the edge. Because the effect
depends on reaction products its increased where the developer is highly
diluted or where there is insufficient agitation to wash away reaction products
at the surface and bring fresh developer there. When the effect is not extreme
it enhances sharpness. Note that this is sharpness not resolution. Sharpness
developers were long popular for 35mm use because they tend to compensate for
the lack of sharpness caused by insufficient film and lend resolution. More
modern films have better resolution. However, the eye tends to judge sharpness
by edge contrast so a high resolution but relatively low contrast image will
look less sharp than one with high edge contrast but considerably lower actual
resolution. Extreme edge effects can look like someone drew lines around
objects. This used to be a serious problem with motion pictures because the
release print was often several generations from the original. Each
generation increased the edge effects until one got "edge crawl". Edge
effects and compensation are related since both depend on local exhaustion of
the developer.
Dome developers, notably hydrquinone, have reaction products that tend to
accelerate development while others, like metol, tend to suppress it. Some
combination developers have little edge effect due to the mutual cancellation
of the effect by the developing agents. Nonetheless, developers like D-76
will become edge effect developers when diluted to 1 part stock to 3 parts
water or more.
--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
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--
Richard Knoppow
dickburk@xxxxxxxxxxxxx
WB6KBL
