[pure-silver] Re: ID-11 and D-76
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Thu, 24 Apr 2008 12:30:01 -0700
----- Original Message -----
From: "Shannon Stoney" <shannonstoney@xxxxxxxxxxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Thursday, April 24, 2008 8:20 AM
Subject: [pure-silver] ID-11 and D-76
I have always heard that ID-11 and D-76 are the same
formula. But Ilford does not seem to think so. I was
looking at the film boxes for HP5+ and FP4+, and the boxes
say to develop both films for 11 minutes in D-76 1:1. But
with ID-11, you develop HP5+ for 13 minutes and FP4+ for
11 minutes. I thought it might be a misprint so I went to
the website, and it said the same thing.
Weird, huh.
--sghannon
The _published_ formulas are the same but the _packaged_
developers are somewhat different. Kodak uses the buffered
version of D-76 which has been published as D-76d. This is
more stable in activity than the original formula. Probably
both contain sequestering agents, etc. The activity may not
be exactly alike.
However, I think the cause of the different times has to
do with differences in the sensitometry. Ilford's
measurements may be later than Kodak's or there may be other
small differences in testing. I think they also specify
different agitation techniques although that should not make
a significant difference.
Ilford also uses a different contrast index target. Kodak
charts are for a contrast suitable to contact printing and
diffusion enlarging. Ilford uses a compromise contrast index
midway between diffusion and condenser values. However, that
should result in slightly shorter development time, not
longer.
In fact, the only way to check if the times are correct
is to test them. I think I would trust Ilford on this one.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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