[pure-silver] Re: ID-11 and D-76
----- 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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