Swedish Ascorbic Acid Developer

[Alan Johnson]

In the thread on Ascorbate Chemistry it was mentioned that a Swedish patent described a developer which contained an excess of borax and glycerol, the idea being that they form a complex which stabilizes the developer against pH change thereby making it long lasting, so long as it is not allowed to oxidize.
http://www.google.com/patents/US3022168
As this idea was not tested by Kodak, I propose to try it but first would like to know if there are any comments on the proposed formula, based on examples 2 and 4 of the patent.Salicylic acid is to reduce oxidation, I have left out TEA for simplicity, there being some uncertainty about its effectiveness.

Dimezone-S.....................0.2g
Ascorbic acid....................10g
Sodium Sulfite anh.............40g
Borax decahydrate.............15g
Glycerol..........................70ml
Salicylic acid......................1g
Sodium hydroxide,,,,to pH =about 8.4
Water to.................. ........1L

It will be kept in a 1L glass bottle with no special precautions (eg not topped up with inert gas).

 

[Photo Engineer]

That looks familiar to me. If I recall anything, I'll post it.

PE

 

[Luis-F-S]

I'll try it if I'm ever in Sweden.

 

[Gerald C Koch]

Salicylic acid is to reduce oxidation, I have left out TEA for simplicity, there being some uncertainty about its effect.

The TEA and salicylic acid are chelating agents respectively for copper and iron to prevent the Fenton reaction. Leaving the TEA out may also throw off the pH a bit.

 

[Alan Johnson]

On reflection I think I figured out the significance of the Swedish Patent.
They were not trying to slow oxidation of ascorbate using additives, as in Xtol and DS-10, but to prevent the products of oxidation causing a pH drop by using the glycerol-borax complex.
Therefore to give the idea of the Patent a proper test I propose to use chemical constituents as in their example 2, except 6g Potassium Hydroxide will be replaced by 6 x (40/56.1) = 4.3 g Sodium Hydroxide.

Swedish Ascorbic Acid developer SA-2
Metol........................7.5g
Ascorbic acid............10.5g
Sodium Sulfite..........100g
Borax........................15g
Sodium hydroxide......4.3g
Glycerol.....................70g
Water, demin, to..........1L

 

[BradS]

May I ask, and please do not take this wrong, I'm not trying to bust your balls....but, I am sitting here wondering...

What is the goal here? Especially with this second recipe? The SA-2 adds a bunch of ingredients to D-23...which adds cost and complexity. Are we trying to improve upon D-23 - photographically, commercially or ? It is an interesting pursuit but from here it just looks like they're adding Sodium Ascorbate (Ascorbic acid + NaOH) to D-23 and then trying to address the instability of the Ascorbate.....and I'm wondering...why? What do we get for all of those extra ingredients?

 

[mrred]

I'm not sure you can compare sa-2 to d23.....only that it does develop film too. Just by adding the ascorbic acid the developing properties significantly change.

However there doesn't seem to be much thought in the amount of Metol and Sulfite thrown in there. Less than an optimum mix. The original amount of Sulfite was probably ok and the Metol should be clawed back or the Ascorbic acid increased. Ascorbic acid is usually 6 times the amount of Metol to be optimum.

 

[BradS]

I'm not sure you can compare sa-2 to d23.....only that it does develop film too. Just by adding the ascorbic acid the developing properties significantly change.

However there doesn't seem to be much thought in the amount of Metol and Sulfite thrown in there. Less than an optimum mix. The original amount of Sulfite was probably ok and the Metol should be clawed back or the Ascorbic acid increased. Ascorbic acid is usually 6 times the amount of Metol to be optimum.

....well, that is exactly why I compared it to D-23....7.5 Grams of Metol and 100 G of Sodium sulfite in a liter of water is exactly D-23.


I am not at all convinced that the Ascorbate has any significant photographic effect in this case either...but that is, of course, the point of the experiment.

 

[mrred]

It will be super additive and make the developer more potent. Just not using all it's potential. The ascorbic acid will make a finer grain reducer so all that sulfite would not be needed, for sure. I would keep the Ascorbic acid the same and reduce the amount of Metol to 1.6/1.7 g and you would have a developer much more powerful than D23. If you left the Metol and Ascorbic acid the same, it would be more powerful still, just not as a proportional increase.

 

[Photo Engineer]

AHA moment.

A sugar + borate are the ingredients in slime, a commercial toy product. This forms a semi solid jelly like product that can be molded, shaped and otherwise manipulated.

I'll bet this mix will do that or come close by making a very viscous mix that can be stored for long times as a semi solid. If not, then it failed to meet the unspoken (unwritten) desires of the patentees.

PE

 

[Gerald C Koch]

Are we trying to improve upon D-23 - photographically, commercially or ?

I have found PA and MA developers to be finer grained than their PQ and MQ equivalents. Ascorbic acid seems to produce finer grain than hydroquinone. I was really surprised when I first used an ascorbate based paper developer either DS-14 or DS-15. The increase in detail was quite striking.

 

[MattKing]

AHA moment.

A sugar + borate are the ingredients in slime, a commercial toy product. This forms a semi solid jelly like product that can be molded, shaped and otherwise manipulated.

I'll bet this mix will do that or come close by making a very viscous mix that can be stored for long times as a semi solid. If not, then it failed to meet the unspoken (unwritten) desires of the patentees.

PE

If it were to be marketed, would you call it Slimadol?

 

[Alan Johnson]

I haven't seen any slimy things crawling with legs in it yet:http://www.bartleby.com/101/549.html

First impressions of SA-2 (I think this test may take some months to see if the glycol-borax preserves it):
The start pH was 8.2 +/- 0.1.
The development time seems about the same as Xtol 1+0.
The EI seems similar to Xtol 1+0
For comparison I have prints of the same subject, all with Delta 100, in Xtol 1+1, 510 Pyro and SA-2.
SA-2 is about as sharp as 510Pyro and marginally sharper than Xtol 1+1.
510 pyro has the finest grain followed by Xtol 1+1 and SA-2 is the most grainy but they are all pretty fine grained.

 

[Photo Engineer]

This patent predates the work of Ryuji Suzuki. In fact, it may be the basis of some of his work. IDK.

PE

 

[Gerald C Koch]

Deleted post. I wondered why I couldn't see them mentioned but attributed it to bad eyesight on my part.

 

[Photo Engineer]

I don't think so! And there are a lot of reasons for that thinking.

PE

 

[Gerald C Koch]

I have heard it mentioned that the drop in the price of ascorbic acid had a part. Before health stores became popular the price of AA was rather high. I can remember being quoted a price of $18 dollars in the early 60's for 125 g. Today that same price will buy several pounds. If true then it is funny how things work.

 

[Photo Engineer]

Well, basically it was the Fenton reaction that was the stumbling block. And, packaging. Ascorbic Acid goes bad rapidly in big packing operations. Vitamin C can vary quite a bit but not a developer.

So Sylvia and Dick did a lot of new work on this. Groundwork was laid by Henn and Lee as well.

PE

 

[Relayer]

Alan, may be you interesting with my result about stability of ascorbate development. In my experiment I found that any combination of Ascorbic Acid + Box is unstable and pH very changed after 1-2 week. But if you replace AA with Sodium Ascorbate - this solution have stable pH.
PS I experiment with pH in range 8-9

 

[Alan Johnson]

Hi Relayer,
Plenty of time to discuss things on this topic, my test of the Swedish developer may take months, I hope.
It reads like in your test most of the borax was used to neutralize the ascorbic acid but much less is needed to neutralize sodium ascorbate as that has a pH (IIRC ~5) much higher.
Do you care to give more details?

 

[Alan Johnson]

Routine progress note.
After 7 weeks, 9 films developed , time now extended from (Xtol 1+0) +10% to +30%. pH still 8.2 +/- 0.1
Airspace in 1000 ml glass bottle now 350ml, developer still colorless.Attachment from Acros , film 9.

 

[Trask]

A parallel question, with no disrespect intended at all: I have never heard of a Swedish photographic chemical company that produced developers, whereas I've heard of US/UK/Japanese/German/etc companies. So who are "the Swedish guys?" I would assume that they didn't stumble across this stuff but developed it specifically -- but for what commercial purpose? Domestic production?

 

[Alan Johnson]

Sorry, I don't know much about it except the patent is sometimes quoted as preceding Xtol.
It was granted to a Swedish company 53 years ago.

 

[Alan Johnson]

After 18 weeks I now developed 13 films in this 1 liter of SA-2. The pH is 8.3+/- 0.1 so the glycerol seems to be working to keep the pH constant. The development time is Xtol 1+0 plus 30% (attachment, TMY-2).
However, after about 10 films a grey suspended deposit appeared in the developer, possibly due to sulfite dissolving and redepositing silver . IMO 10 films is about the limit for a 1L batch without inconvenient filtering.
My guess is that the developer was probably not commercial as the liquid glycerol ingredient cannot be sold in packs for mixing in water.

 

[Photo Engineer]

This looks similar (I think) to one that Ryuji posted on his former web site. Not sure, but it seems to be in my memory.

Which came first though, I can't even guess.

Looks good.

PE