Suggestion for beginners: start with D76, skip the monobath

Started 7 months ago | Discussions thread
Deardorff Senior Member • Posts: 1,587
Re: Suggestion for beginners: start with D76, skip the monobath

Here's Richard Knoppow's explanation from Pure Silver:
The published formulas for ID-11 and D-76 are identical but the
packaged developers are not.
One big reason for the difference in recommended time is that Kodak
and Ilford use different contrast indexes or average contrast to
determine the contrast. Kodak bases all of its pictorial film
development times on a CI suitable for contact printing. For average
condenser enlargers the time should be reduced from 15% to 25%
(depending on the film) with a consequent decrease of film speed of
about 3/4 stop. Ilford bases its times on an average CI midway between
diffusion and condenser times. Plus, Ilford does not use the ISO
method for determining speeds. They don't say what system they use but
claim their speeds are more nearly practical. Oh, dear; so much for
standardisation in the modern world.
The CI required by the ISO speed method is actually close to that
required for diffusion printing on normal grade paper given an
"average" scene brightness range. Lots of room for qualification
Lots of film makers give times for D-76 these days, but not all
indicate what CI they are developing to.
Heigh-ho, time to dig out that old densitometer again.
Richard Knoppow
Los Angeles, CA, USA

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In regards to ID-11 vs. D-76, the published formulas are identical,
but neither Kodak nor ILFORD produces a product exactly like the
published formual. Both commercial products have additional buffers
and preservatives. In some films, they will produce slightly
different results. Sometimes, the differences are enough that ILFORD
ends up with different recommendations for the two developers, but
because of rounding, the difference may not be as much as it appears.


In practical applications, it is safe to use the published time for
ID-11 with D-76, and vice versa. If you are doing precise work, you
will need to pick one developer and stick with it.


David Carper
ILFORD Technical Service

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