PDA

View Full Version : Improved version of DS-10 by Ryuji Suzuki?



Pages : 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 [28] 29

Gerald C Koch
04-20-2012, 10:30 AM
I don't know its effect on superadditivity but ammonium thiocyanate is a silver solvent and it dissolves in propylene glycol on gentle heating (I just tried it).All else I know about thiocyanates in film developers is that there is some potassium thiocyanate in Spur HRX-3 developer and IIRC it was noted that Kodak were doing some experimental work at one time.

Ammonium thiocyanate is not going to enhance superadditivity. A sulfite is what is really needed. Thiocyanates are not needed for BW processing except for reversal processing. In fact they can cause fog with modern emulsions.

albada
04-21-2012, 12:51 PM
A sulfite is what is really needed.

Last night I discovered a way to provide sulfite in a propylene glycol concentrate!

I'm aware that sodium and potassium sulfite do not dissolve in PG. But last night I decided to try putting potassium sulfite (PS) in PG as a suspension. I poured a 45% aqueous solution of PS into some PG, and heated it to 90-98C for a while to drive out the water. The resulting suspension works well. The PS does not coalesce into a gooey mass as sodium sulfite does (which I also tried). Instead, the sediment of PS remains a fine powder which is easily shaken back into suspension. I let it sit overnight in a capped test tube, and shook it this morning, which gave a perfect-looking suspension with no residual sediment on the bottom.

This suspension technique appears to be a plausible way to provide sulfite in a concentrate. But one must remember to "Shake well before using".

Any comments from chemists about this? Has this idea been tried and rejected in the past for some reason?

Mark Overton

Photo Engineer
04-21-2012, 01:43 PM
That sounds reasonable. The drawback is the "shake well before using". I'm not sure how that would work out, but my prior experience with situations like this have not been very good.

PE

brianmquinn
04-21-2012, 02:12 PM
TF4 fixer is a shake well before using concentrate. I always shake well and pour off about 125ml to make working dilution fixer.
By the time I get to the last 1/4 of a bottle there is a lot more solid in the bottom per volume of liquid then when I poured off the first batch. That is one reason I switched to TF5.

Photo Engineer
04-21-2012, 02:13 PM
And that is one reason why Bill and I designed TF-5! :)

PE

albada
04-21-2012, 02:34 PM
TF4 fixer is a shake well before using concentrate.

Ron, how long does the ammonium thiosulfate stay in suspension? (I'm presuming thiosulfate is the solid). I know this time depends on several factors -- density of solid, viscosity of liquid and size of particles -- so I'm trying to compare that with sulfite-in-PG. Maybe I should just buy some TF-4 and take a look. :)

Mark

Photo Engineer
04-21-2012, 02:53 PM
The solid is not hypo. I am not at liberty to disclose the formula any further. Sorry.

PE

albada
05-02-2012, 01:50 AM
I recently tested both Phenidone and Dimezone S in identical PC developers, under identical conditions. Both were at pH 8.00. Here's the one-litre formula:


Potassium sulfite 45% solution ..... 126 g
Sodium metaborate 4 mol ............. 1.93 g
Ascorbic Acid .............................. 5.5 g
Phenidone / Dimezone S .............. 0.05 g / 0.10 g

pH=8.00, TMY2: 13.5 minutes at 20C.


And here are the curves:

50249

The contrasts (slopes) are approximately the same, yet Phenidone has a noticeably higher toe, indicating higher speed. And this despite the low concentration of Phenidone (half that of Dimezone S). I'm guessing this means that, as pH drops, Dimezone S drops in activity faster than Phenidone, especially in the toe-area. Sound reasonable?

Mark Overton

Ian Grant
05-02-2012, 03:27 AM
Yes, this is why Phenidone is preferred in commercial film developers while paper developers from the same companies may often have switched to Dimezone.

Ilford's PQ fine grain commercial photofinishing developer Autophen, also known as the Axford-Kendall developer, was a PQ fine grain developer that could be replenished continually for very long periods of time and contradicts the supposed poor keeping qualities of Phenidone based developers. Unlike smilar MQ developers (D76/ID-11) it wasn;t prone to collapse through build up of bromides etc

Ian

john_s
05-02-2012, 04:18 AM
Yes, this is why Phenidone is preferred in commercial film developers while paper developers from the same companies may often have switched to Dimezone........................Ian

Very interesting. I'm using Dimezone-S in my ID-78 paper developer and in Pyrocat-HD. Is there a pH level above which Dimezone-S equals the toe contrast of phenidone in a film developer? Next time I need a speed enhancing developer I was thinking of mixing some ID-68 (often called "Microphen substitute") using Dimezone-S but maybe I should get some phenidone for that.

Gerald C Koch
05-02-2012, 10:48 AM
I switched to Dimezone-S even though it is more expensive after I had to trash a 250 g jar of phenidone that had changed to a black tarry mess. So far the Dimezone has remained fine.

Photo Engineer
05-02-2012, 03:33 PM
The switch to Dimezone-S was under way when R&D on B&W process chemistry stopped at EK.

It is far more stable in solution. It can be engineered to give identical results as a Phenidone developer.

PE

Ian Grant
05-02-2012, 04:24 PM
I switched to Dimezone-S even though it is more expensive after I had to trash a 250 g jar of phenidone that had changed to a black tarry mess. So far the Dimezone has remained fine.

The problem is that Phenidone is a generic mane that covers a few variations. I still have early 1960's Ilford Phenidone (it has their date code) that's perfect, it's as good today as the newer Phenidone I've bought since, definately no change in colour. Others have found the same remarkable keeping properties.

It's interesting that some US writers claim it has a poor shelf life while those in the UK say it has a long stable shelf life. Kendall's original Phenidone had poor keeping properties which was why it was well over a decade before a more stable derivative it went into commercial production. Now when LA Mannheim wrote that it was stable he was working with Pavelle alonside Kurt (Curt) Jacobson and had good links with Ilfords chemists Axford & Kendall.

Ian

Photo Engineer
05-02-2012, 04:40 PM
Phenidone was first made in 1890. It was found to be a good developing agent in 1940, and was not commercially available until the 1950s. It is what is called a hydrazide or a compound made from an acid and hydrazine. It is easily hydrolyzed in alkali solution (developer) to ring open and become ineffective.

To combat this, Dimethyl Phenidone was synthesized. It is quite active and less subject to ring opening due to the two methyl groups present which protect the ring.

Finally, scientists made HMMP, or Hydroxy Methyl Methyl Phenidone, or Dimezone-S as it is now known. It is almost impervious to ring opening and is very very stable in alkali. It can be used in instant products in the goo at pH values up to 14 with no degradation, and it is as active as the original Phenidone as long at the developer is adjusted for the higher molelcular weight and a slightly lower base activity.

Developer concentrates with plain Phenidone have been known to be DOA, but not so with Dimezone-S developers. Also, depending on purification method, Phenidone can go bad on the shelf as Gerald described above.

PE

john_s
05-02-2012, 05:28 PM
.......and it is as active as the original Phenidone as long at the developer is adjusted for the higher molelcular weight and a slightly lower base activity.....
PE

Thanks PE. The adjustment for MW is about 1.27 if I remember correctly. What additional adjustment is needed for its intrinsic lower activity?

I found Albada's experiment (above) interesting as I guessed that using 2x the amount of Dimezone-S compared to Phenidone would have been sufficient to get the same result, but his experiment seemed to show lower shadow contrast. Or am I splitting hairs?

Photo Engineer
05-02-2012, 05:52 PM
John;

You note that Mark's experiment was almost dead on. Based on that, only minor tweaking would be needed taking off from any formula to match the two developing agents. On a given developer, I once did it by making up developers and adjusting the Dimezone-S in 100 mg/l increments until I got the matchup I wanted. It worked fine. In any event, the "mismatch" is so small it might vanish with repeated experiments. A 0.05 Log E to 0.10 log E variation can be common in some experiments. I think on that basis, you may be splitting hairs.

PE

Ian Grant
05-02-2012, 06:07 PM
In many respects John it may be splitting hairs but no substitution of one developing agent for another no matter how closely related will give identiacl results particularly with film developers if scrutinised closely. It may be that the levels of the other components need tweaking to get closer, and also the ratio may need to be different depending on the overall formula,

In the case of Microphen/ID-68 Ilford exploited the slight speed increases they'd found with early PQ versions of ID-11/D76 (which became Autophen). With Microphen they droped the sulphite level, altered the buffering, further optimised the PQ ratio to gain a slightly greater film speed at the expense of a less fluffy grain structure, as a conseqience Microphen negatives have better shadow detail when push processed but garin looks more pronounced.

The reality is you work with what gives good consistent results, you only try to improve on it if the need is there.

Ian

albada
05-03-2012, 01:57 AM
When I developed the test strips for those curves, the tank was in a water bath which allowed me to keep the temperature within +/- 0.2C. I measured the chemicals with an electronic scale with 0.001 g resolution. So I doubt that I messed up either strip, so the curves are probably close. I've also noticed in test photos that Dimezone S delivers a bit less shadow-detail than Phenidone at the low pH of 8.0. It would be easy to run the tests again with a pH of 8.25 and compare those curves, and maybe I'll try it out of curiosity.

John:
Dimezone S works well in XTOL at pH 8.25. And Microphen and its clones have a pH of nearly 9.0, so you'll be well above 8.0 with ID-68. Also, DD-X and Ultrafin-plus are what I call "DQ" developers, using DimezoneS-hydroquinone instead of Phenidone-hydroquinone (PQ), so the DQ combo must work fine. And Ultrafin-plus has a pH of 8.9, about the same as ID-68. Based on all that, I'd guess that using Dimezone S in ID-68 would work fine.

Mark Overton

Photo Engineer
05-03-2012, 11:26 AM
Mark;

A good exposure on the straight line portion of the curve will be essentially identical in both cases. As for variations, any process result is the cascaded result of exposure, process time and temp, and mixing. Any variation in any one or two of these can lead to small differences. I have run 5 or 6 strips of film through the same process at the same time and have gotten tiny differences in the curves. Smaller than I stated above, but still differences. So, in different developers, the differences are probably going to be larger as I noted before.

PE

john_s
05-03-2012, 06:51 PM
In many respects John it may be splitting hairs but no substitution of one developing agent for another no matter how closely related will give identiacl results particularly with film developers if scrutinised closely. It may be that the levels of the other components need tweaking to get closer, and also the ratio may need to be different depending on the overall formula,

In the case of Microphen/ID-68 Ilford exploited the slight speed increases they'd found with early PQ versions of ID-11/D76 (which became Autophen). With Microphen they droped the sulphite level, altered the buffering, further optimised the PQ ratio to gain a slightly greater film speed at the expense of a less fluffy grain structure, as a conseqience Microphen negatives have better shadow detail when push processed but garin looks more pronounced.

The reality is you work with what gives good consistent results, you only try to improve on it if the need is there.

Ian

Thanks Ian. I'm not sure how I'd go about the tweaking, but first I'll get started and take it from there.

I notice on the web site

http://www.lostlabours.co.uk/photography/formulae/developers/devID68.htm

the formula for ID-68 contains no bromide although the replenisher does. I have used Pyrocat-HD without bromide (as suggested for some uses by Sandy King who invented it) which is supposed to give marginally more speed at the expense of a little fog. Is the bromide essential for the ID-68?