Phenidone vs. dimezone?

[Rudeofus]

What happens to these silver sulfite complexes that remain in the emulsion? Are they removed by the fixer?

My guess is they would be developed very very close to the grain they come from. Whatever happens, they don't seem to make it into the developer tank, and development on the emulsion surface would show up as dichroic fog.

 

[john_s]

........., I guess I've just got used to using Pyrocat HD I like the results I get with it, I find the negatives print easily. It's no better than Xtol and equally it's no worse, it's just a different approach using a staining developer.

Ian

I also use Pyrocat-HD for nearly everything, but I do take a small speed hit compared to Xtol or ID-68 which I use if I need a bit more speed.

I noticed that the formula for ID-68 (more borax) would produce a higher pH than Autophen: would that be responsible for the extra speed and grain? Does Autophen give as much speed as ID-68?

 

[albada]

Xtol was a new generation developer better fine grain than any PQ or MQ developer I'd used

That's what I was wondering. It appears that replacing hydroquinone with ascorbate improves both grain and speed.

BTW, according to my notes, the MSDS for DD-X says it contains hydroquinone and Dimezone S, not Phenidone. Maybe Dimezone S + hydroquinone can match PC?
Mark Overton

 

[Rudeofus]

That's what I was wondering. It appears that replacing hydroquinone with ascorbate improves both grain and speed.

I have no direct reference in literature, but Ron claimed, that there was nothing particularly attractive about ascorbates except their lower environmental impact. If you study patent literature from 80ies on, there are some patents with the aim to reduce/avoid HQ in developers.

BTW, according to my notes, the MSDS for DD-X says it contains hydroquinone and Dimezone S, not Phenidone. Maybe Dimezone S + hydroquinone can match PC?

XTol is also made with Dimezone-S. The main difference between DD-X and XTol is, that the former emphasizes speed over grain and sharpness, whereas the latter tries to strike a balance with maybe a slight nod to sharpness. DD-X sums up decades of research into Phenidone/Dimezone-S based developers, whereas XTol embodies Kodak's ideal of a developer.

 

[Alan Johnson]

IIRC, PE once posted that after developing Xtol Kodak labs were working on thiocyanates before the work was shut down.
It appears that Spur in Germany have continued to work on improving developers with the HRX series.
Here is the msds of what appears to be an early one of the series, it contains metol, phenidone and dimezone-s:
https://www.fotoimpex.de/shop/images/products/media/56160_2_MSDS_DE.pdf
This suggests the use of both phenidone and dimezone together may give results that the inventor considered an improvement at that time.
HRX has since gone through more changes, IDK what is in the 2020 version.

 

[Lachlan Young]

Here is the msds of what appears to be an early one of the series, it contains metol, phenidone and dimezone-s:
https://www.fotoimpex.de/shop/images/products/media/56160_2_MSDS_DE.pdf
This suggests the use of both phenidone and dimezone together may give results that the inventor considered an improvement at that time.

The more I look at some of the oddities Spur produce, the more I wonder if there's some attempt going on at making an Electron Transfer Agent type of developer.

 

[Ian Grant]

That's what I was wondering. It appears that replacing hydroquinone with ascorbate improves both grain and speed.

BTW, according to my notes, the MSDS for DD-X says it contains hydroquinone and Dimezone S, not Phenidone. Maybe Dimezone S + hydroquinone can match PC?
Mark Overton

As Dimezone-S is is classed as being in the Phenidone group of developing agents then we can call DD-X a PQ developer.

Ilford use (or list) Phenidone and Phenidone-B in Harman Warmtone developer and Dimezone-S in PQ Universal and Multigrade developers according to the MSDS. To achieve warmer tones you need finer grain (in the paper).

Maybe Spur and Ilford have found two different Phenidone (or derivates0 work better than one.

Ian

 

[Rudeofus]

This suggests the use of both phenidone and dimezone together may give results that the inventor considered an improvement at that time.

It has been stated here, that lower amounts of individual ingredients, even if a few of them essentially do the same, can help reduce the red tape to cut through when releasing a new product.

 

[Alan Johnson]

In 2014 Henning Serger chose HRX to use for his film tests, IDK if he still uses it.
https://www.photrio.com/forum/threads/rollei-rpx-25-grain-and-resolution.115244/page-3#post-1523277
His results are published in a printed magazine I believe.
https://www.photrio.com/forum/threads/research-and-development-of-film.94925/page-2#post-1261838

 

[Lachlan Young]

It has been stated here, that lower amounts of individual ingredients, even if a few of them essentially do the same, can help reduce the red tape to cut through when releasing a new product.

Or there's something else going on involving some sort of attempt at making an in-situ synthesis - and there also seems to be a lot of HQMS-K in there. I really can't see it being a regulatory workaround.

 

[Anon Ymous]

Or there's something else going on involving some sort of attempt at making an in-situ synthesis - and there also seems to be a lot of HQMS-K in there. I really can't see it being a regulatory workaround.

HQMS is much milder than hydroquinone and is used at a much larger quantity in E6 FD than what a typical hydroquinone quantity would be for a bw developer.

 

[albada]

Mark, have you read “The Genesis of XTOL” by Dickerson/Zawadzki (the Kodak principals on the project)? Granted there’s an inevitable marketing element and it isn’t a deep technical paper but still worth reading. I’d also suggest studying the XTOL-related patent (and the earlier infamous “Swedish patent”).

I've read the patent, but not their paper. I'd probably need to go to a large library to find it, as I didn't see it online.

Anyway, I've been wondering for a while about whether the best PQ can match the best PC on the three traits (grain,speed,sharpness).
If C was substituted for Q solely to reduce toxicity, and if Ron was correct when he claimed that "there was nothing particularly attractive about ascorbates except their lower environmental impact", then PQ should be able to match PC.
That would allow us to avoid the troublesome Fenton reaction that destroys ascorbates.
Mark Overton

 

[Rudeofus]

People say great things about FX-39. Is it worse than XTol ?

 

[Alan Johnson]

The oxidation product of hydroquinone is itself a developer while the oxidation product of ascorbate is an acid which inhibits development and it is postulated that for this reason ascorbate should be slightly sharper. IIRC, this was first pointed out on APUG by Gainer. I believe Kodak claimed a small (10% ?) increase in sharpness for Xtol vD-76 when Xtol was first introduced.
FX-39 was said by Crawley to be similar to FX-37 which is a mid acutance developer, rather different from Xtol, IIRC its pH is about 10.5 and it is mainly for use with tabular and similar grain films.