Return of the Son of AZO

[holmburgers]

That's a great looking cat! That negative appears to be perfectly suited for the paper range. About what contrast grade would you say you're getting with this 'Son of AZO'?

[Hexavalent]

That's a great looking cat! That negative appears to be perfectly suited for the paper range. About what contrast grade would you say you're getting with this 'Son of AZO'?

I'd ballpark S of A as grade 2 - the Nellie Cat neg has lots of contrast.

[dwross]

No, it does not hurt and it is particularly good with AgCl and AgClBr emulsions. I did a study on this at Kodak. It can actually increase speed and development rate depending on emulsion type and grain size.

PE

Ron,

This has the sound of one of those things that will be in your book, but are you willing to expand on a few more details?

Thanks,d

[Photo Engineer]

At EK, I did a series of TAI levels with two AgClBr emulsions, one was 0.2 micron and the other was 1.0 micron. The TAI had no effect on the smaller grain emulsion but it had a huge effect on the coarse grained emulsion. The coarse grained emulsion became more developable by a large factor, and gained a small amount in speed. The work was written up but we did not go ahead with the R&D as they solved the speed / development rate of the coarse grained emulsion by another means. This work later was written up as a Research Disclosure or a Defensive Publication and is somewhere in the literature.

There was a slight difference in the halide ratios of the two emulsions to help with the grain size. We never were able to determine if this had anything to do with it. This was extrapolated into the AgCl field but not followed through. Ian has indicated a gain in development rate as well, but it is not clear if the washing or the TAI caused the effect of faster development that he has seen.

PE

[dwross]

Thanks. Really interesting. I'm not sure I value faster development for its own sake, but the possibility for an increase in speed without the usual tradeoffs is always compelling. I think I'll give it a test or two sometime soon. So many factors to tease out. Gotta love it.