Metol Ascorbate keeping properties

[Alan Johnson]

The 5x concentrate of Ryuji Suzuki's DS-2 developer is:
Metol..........................2g
Ascorbic Acid................5g
Sodium Carbonate..........20g
Sodium Bicarbonate.........5g
Sodium Sulfite................100g
Water to make.................1L
1 part of this is diluted with 4 parts water to make the working solution,target pH 9.8.Develop 100 T-Max 12 min 68F.

I stored the 5x concentrate in a full sealed glass bottle for 9 1/2 months and then found it to be colorless and to develop film as well as freshly prepared concentrate.

By contrast, a 1/3 full bottle of concentrate 9 1/2 months old went orange and did not work, producing only blank film.

Generally the shelf life of developers is quoted assuming them to be kept in part full bottles unless specified otherwise.IMO this test shows that,like certain other developers, the metol ascorbate at pH~10 is long lasting if air is excluded.

I plan to keep this DS-2 under inert gas,there are other threads about this.I just wrote this up because I thought the stuff might decompose in a sealed bottle by hydrolysis but it did not.

 

[john_s]

Thanks for the info, Alan. I'm a great believer in concentrated solutions for this very reason. I keep double strength Xtol in full bottles for 6 month without problems, made with our local tap water which isn't too bad.

How do you like results that you get with the DS-2?

 

[Alan Johnson]

Usually I am now using replenished Xtol but for occasional use I wanted a developer giving similar high film speed with more acutance and DS-2 is so far looking promising if it keeps under inert gas.
I was using FX-37 before but DS-2 is easier to make.
I get box speed with DS-2 and 100 T-max under sun/shade conditions which is good,expect even higher with Delta 100.

 

[Zathras]

Let me preface this by saying I am not a chemist, but I wonder what would happen if the carbonate was omitted from the stock solution, and added from a 10% sodium carbonate solution to the diluted developer? Wouldn't the resulting stock solution be at a much lower pH, possibly increasing its shelf life? Just another weird idea of mine, I have lots of 'em.

I might just have to try it for myself and see if this is a workable idea.

Mike

 

[john_s]

I remember reading something from Ryuji Suzuki about the life of ascorbate in a developer not behaving as other developing agents do. That is, it kept better at high pH. His site has been streamlined, removing some very informative articles about developing film and paper. I'll have a search through my saved bits and pieces and see what I can find.

 

[Alan Johnson]

Zathras,
I think you are right.
This is from the msds of the discontinued Paterson FX-50:
Part A
Sodium Ascorbate.....................<2%
Sodium Sulphite.......................12-14%
Part B
Potassium Carbonate.................7-9%
Evidently Geoffrey Crawley,who formulated this,must have considered it would keep better if the carbonate part was was kept separate.IDK what would be the developing agent (phenidone,dimezone,metol etc) in part 1 but it is not stated in the msds.

John,
More about DS-2:
Ryuji's website silvergrain.com/labs/ was down when I looked but I have notes on what was on it.He said:
"For strictly fresh preparation and one-shot use, DS-2 is photographically very similar to DS-12...
The result of processing TMX in DS-12 was sharp and very fine grained prints of rich shadow separation without over-compressing midrange or highlights.Highlight density keeps going up even with moderate overexposure and overdevelopment, without losing too much contrast.Therefore, with scenes of wide tonal range,quite a bit of burning in is often necessary,but good local contrast is maintained in highlight areas. All these are what I expect from TMX but, but they are hard to get with standard developers"

 

[Gerald C Koch]

The keeping properties of DS-12 are probably better than DS-2 since it contains two chelating agents to prevent Fenton oxidation of the ascorbic acid. Triethanolamine and salicylic acid are used to bind any iron ions. Neither chemical is difficult to obrain. Salicylic acid can usually be obtained from a compounding pharmacy and triethanolamine from sites that sell photo chemicals,.

 

[Alan Johnson]

One thing I noticed in this test, DS-2 and DS-12,which use metol, are not very active even at pH 9.8,taking 12 min to develop 100 T-max.
Therefore if it was wanted to make the finest possible grain ascorbate developer with no sulfite,a low pH (to prevent grain clumping or strictly the appearance of it)combined with phenidone ,which is more active than metol, in combination with ascorbate,would be worth a try.
I don't think anyone has ever tried to make the finest possible grain ascorbate developer with no sulfite.

 

[Gerald C Koch]

A high sulfite concentration is not needed for fine grain with ascorbic acid based developers since the ascorbic acid itself provides finer grain than hydroquinone. This is because there is far less infectious development with ascorbate than with hydroquinone.

Both Ds-2 and DS-12 use metol rather than phenidone to achieve finer grain. Substituting phenidone in these formulas may actually increase the grain produced. Both formulas produce very fine grain.