Return of the Son of AZO

[Hexavalent]

Back in the lab after a hiatus (gainful employment).
Measured, mixed, stirred, cooked and coated a variant of PE's AZO formula.

A couple examples attached: "Nellie cat" looking rather grumpy after having her sunbeam nap interrupted, the boardwalk at Mer Blu, late October afternoon.

I highly recommend Ron's Emulsion workshops for anybody wanting to get their hands into emulsion-making -- if you enjoy rolling up your sleeves, learning through hands-on, and being in photo Mecca (Eastman House).

 

[Photo Engineer]

Mercy beaucups!

PE

 

[dwross]

Very nice, Ian! Can you share the gist of your variation?

 

[Jeff Kubach]

Wow! excellent opictures.

Jeff

 

[Hexavalent]

Without revealing Ron's formula, I can say that it's a partially washed emulsion with a wee dollop of TAI added.

 

[dwross]

Interesting! Can you discuss your decision to add TAI? No requirement to explain your secret sauce, of course. I'm just a hopeless emulsion geek who can't be in the darkroom for another three weeks and I'm going nuts .
d

 

[Hexavalent]

Interesting! Can you discuss your decision to add TAI?

A prior batch of emulsion had fogged somewhat due to storage under less than ideal conditions - TAI is a stabilizer, so I figured a little dollop wouldn't hurt. It didn't hurt

 

[Photo Engineer]

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

 

[Ian Grant]

Ian, how come when I try accessing the emulsion101.com Forum it says my IP address is banned ?

I've many years experience of emulsion manufacture & coating commercially so this seems rather odd.

Ian

 

[Hexavalent]

Ian, how come when I try accessing the emulsion101.com Forum it says my IP address is banned ?

I've many years experience of emulsion manufacture & coating commercially so this seems rather odd.

Ian

Your IP (or a range) has probably been flagged as a source of spam.
PM your ip and email, and I'll put it on the 'okay' list.

 

[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.