Swedish Ascorbic Acid Developer

[Alan Johnson]

Please ignore the formula in post no 1, I had not grasped the idea of this developer then.

The Swedish developer example formula is given in post no 5, it dates from 1962.
It used glycerol, which forms a complex with borax, to stop the pH dropping as the developer oxidises (Patent 2nd page).

Ryuji's DS-10 came after Xtol, in the 2000s:
http://web.archive.org/web/20080930...s/Film_Developer_Recommendations#Introduction
His method was different, like Xtol, he tried to stop the developer oxidizing by chelating the ions that promote the Fenton reaction.

So for about 30 years 1962-1990s when Xtol came along, hobbyists missed out on the use of ascorbic acid, the Swedish patent was ignored.

 

[Photo Engineer]

Without some means of control, then the Fenton reaction is still a problem. They do not mention it.

I wonder how this developer functions without the Metol, or with Metol but no Ascorbate.

PE

 

[Alan Johnson]

The Fenton reaction problem may be the result of a pH drop due to the oxidation products being more acidic than ascorbate. If this is true they can get round it by stabilizing the pH with their glycerol-borax complex.I will let the test run on till 6 months ,admitting air to the developer container occasionally , to see if the pH holds up.
As mentioned by a previous poster, without ascorbate this formula, post no 5, is similar to D-23 metol sulfite developer.
I assume the authors of the patent must have known this in 1962 and since they still took out the patent their formula must have some advantage over D-23.

 

[Photo Engineer]

If your arguments were true, then if you made a regular ascorbate developer with no Borax Glycerol complex present (say, using bi-carbonate), but if you adjusted the pH regularly, then you would prove the statement that pH stabilization prevents the Fenton reaction. If it does not, then something else is going on there.

PE

 

[Alan Johnson]

Thanks to PE for pointing out the significance of the Fenton reaction.
In the thread on ascorbate chemistry I concluded that the pH of sulfite containing ascobate developers was stabilized by an ascorbate sulfite addition product.The Swedish patent claims that it is stabilized by glycerol borax complex.Whichever or both is true it seems likely the Swedish developer will completely oxidize more quickly than developers like Xtol that contain inhibitors of the Fenton reaction.I hope to see if the Swedish formula tested can last 6 months under my test conditions.

 

[Alan Johnson]

I now completed the 6 month test of the formula SA-2 from post no. 5, it being kept in a 1L glass bottle periodically opened to the air when the developer was used.
The same originally mixed sample was used repeatedly, only 500 ml is now left due to losses on each use.
The pH is still 8.2 +/- 0.1.
The development time was increased with re-use because of bromide build-up.
After 12 films the time is increased to 1.3 x the time for Xtol 1+0.

It is hard to distinguish the prints from those produced by developing in Xtol 1+0.
Like Xtol, SA-2 deposits silver sludge when re-used and if it is to be re-used a replenishment method where the sludge is disposed of would be preferred.
IMO it was probably never marketed as the liquid glycerine content prevents it being sold as a powder.
It was probably not economic to sell as a liquid.
However it could be used as an Xtol substitute homebrew although this costs more than using Xtol itself.

 

[sfaber17]

Are you comparing to a similar Xtol made the same time, or fresh Xtol? I somehow think it is fresh and
your SA-2 has a stability advantage? I'm not sure how long Xtol lasts, but got the impression it wasn't long.

 

[Alan Johnson]

Yes, the grain compares with that obtained using fresh Xtol.
Kodak says Xtol lasts at least 2 months in partially filled containers but they are generally pretty conservative:
http://www.kodak.com/global/en/professional/support/techPubs/j109/j109.pdf
I did not test Xtol life, IDK if it is better or worse than SA-2.

 

[Gerald C Koch]

Organic chemicals that have hydroxyl group on two adjacent carbon atoms do form a compound with borates. This property has long been known (~100 years) and has been used in the quantitative analysis of boric acid. Boric acid is a weak acid and has a very hard to determine inflection point when titrated. Typically mannitol is added to the sample converting boric acid into a strong acid with a well defined inflection point. So nothing mystical here.

There is a recipe for a print developer in the BJP containing Amidol and catechol. The catechol is used to regenerate the Amidol but is prevented from acting as a developing agent itself by the addition of metaborate to the solution.

 

[relistan]

@Alan Johnson I'm resurrecting this old thread because I had something to add to the glycerol/borax conversation. I did some testing last week and found that (as Kirk Keyes had mentioned in another thread I don't have the link to), that mixing borax with glycerol actually gets you a pH lower than borax. In fact, I ended up with a pH around 6 from an (apparently) saturated mix. This is because it appears that you get a fair bit of boric acid from the reaction of the two. I also found, that, as PE mentioned in this thread, there is a sort of slime formed in the mixture (this was only glycerol and borax, nothing else), that when heated, turns hard. I wonder if the stabilization effect indicated here was actually just a borax/boric acid buffer? Or perhaps that slime really is doing something.

In any case this developer looks quite good.

 

[Alan Johnson]

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

This was a bit of a red herring as far as the Swedish Ascorbic Acid developer was concerned as it remained a rather ordinary clear liquid for the months of the test IIRC. There was no slime formed.

@relistan you seem to have a mix rather like the toy variety of slime, off topic here.

 

[Alan Johnson]

I did some testing last week and found that (as Kirk Keyes had mentioned in another thread I don't have the link to), that mixing borax with glycerol actually gets you a pH lower than borax. In fact, I ended up with a pH around 6 from an (apparently) saturated mix. This is because it appears that you get a fair bit of boric acid from the reaction of the two.

That explains how the addition of glycerol stabilizes the pH at 8.2. It is needed as the oxidation products of ascorbate are more acidic than the ascorbate itself. However as PE said there is nothing to stop the Fenton reaction.

 

[relistan]

That explains how the addition of glycerol stabilizes the pH at 8.2. It is needed as the oxidation products of ascorbate are more acidic than the ascorbate itself. However as PE said there is nothing to stop the Fenton reaction.

Yeah I didn’t think this led to preventing the Fenton reaction. Just that I thought I knew the reason it stabilized the pH and thought I would share in case it was of use. The relevance of the slime is not so much relevant to this developer, it’s that it renders a developer concentrate in glycerol containing borax kind of useless.

 

[Pentacon_777]

I am new here and with film developers but I have some experience of process chemistry and and education too. I did read that patent and also more articles so I composed next formula (untested but I will test it)
Special 7-DSApLL 1+6 concentrate
Part A
680ml DI water
20g Borax
68g sodium sulfite
82g D-mannitol
3.2g Salicylic acid
12g magnesium sulfate (I read Fenton reaction will be inhibited by Mg+2 ion and that amount sulfate should not harden film emulsion too much)
1.2g Dimezone-S
68g Ascorbic acid
6.6g? Trisodium phosphate (will need adjusting because working solution pH should be 8.4-8.6)
DI water to 1000ml mark

Part B
4600ml DI water
100g Borax
400g sodium sulfite
5.4g Salicylic acid
DI water to 6000ml mark

I did mix above formula today but only test batch 500ml part A scaled down and 1500ml part B scaled down. But I did put TSP only 0.5g before I get calomel reference pH meter. Part A did not became slimy.

 

[albada]

12g magnesium sulfate (I read Fenton reaction will be inhibited by Mg+2 ion and that amount sulfate should not harden film emulsion too much)

Your formula is interesting.
Where did you read that Mg+2 ions inhibit the Fenton reaction? If true, that's valuable to know.

Mark

 

[Pentacon_777]

Your formula is interesting.
Where did you read that Mg+2 ions inhibit the Fenton reaction? If true, that's valuable to know.

Mark

"New Insights of the Fenton Reaction Using Glycerol as the Experimental Model. Effect of O2, Inhibition by Mg2+, and Oxidation State of Fe" ...pdf can be found on Google
Mg+2 is mentioned there and another interesting thing is

Global Sustainability in Energy, Building, Infrastructure, Transportation and Water Technology​

Mentioned on page 268 "Both CO32− and PO43− have a double detrimental effect on the reaction, as they precipitate the iron and as well as scavenges the OH− radicals." That can be found on Google books. And that's why I did choose TSP as alkaline in my formula. It may have effect to oxidation of ascorbate and it may help with iron impurities.
This is also interesting

Effect of phosphate on heterogeneous Fenton oxidation of catechol by nano-Fe₃O₄ Inhibitor or stabilizer? - PubMed

The effect of phosphate on adsorption and oxidation of catechol, 1,2-dihydroxybenzene, in a heterogeneous Fenton system was investigated. In situ attenuated total reflectance infrared spectroscopy (ATR-FTIR) was used to monitor the surface speciation at the nano-Fe3O4 catalyst surface. The...

pubmed.ncbi.nlm.nih.gov

 

[Alan Johnson]

Gainer proposed a simple developer, Ascorbic acid 6g, Phenidone 0.15g, Borax 18.8g, Water to 1L.

Borax Project

Now you can use all the tubs of hardware store borax in your bath and not worry yourself if that kind of borax is good enough for photography! :-) Murray

www.photrio.com

Granted, a little salicylic acid added would chelate iron, but it is hard to see what further benefit would be obtained by adding mannitol ,magnesium sulfate and tsp and by dividing the developer into 2 parts.
btw, the solubility of salicylic acid is only about 2g/L.

 

[Pentacon_777]

Gainer proposed a simple developer, Ascorbic acid 6g, Phenidone 0.15g, Borax 18.8g, Water to 1L.

Borax Project

Now you can use all the tubs of hardware store borax in your bath and not worry yourself if that kind of borax is good enough for photography! :-) Murray

www.photrio.com

Granted, a little salicylic acid added would chelate iron, but it is hard to see what further benefit would be obtained by adding mannitol ,magnesium sulfate and tsp and by dividing the developer into 2 parts.

Dividing into two parts gains probably really nothing but mannitol does if you read the patent that this topic originally based on. Mannitol forms Borax complex buffer as does Glycerol too and that buffer complex seems to be very stable. Magnesium sulfate is my own addition based on my reading about its properties on Fenton reaction as mentioned above. TSP is needed as alkaline to raise pH adequate level but it may serve also other purposes as sited above. This formula needs additional alkaline substance because Borax alcohol buffer is acidic.

As I see you are OP in this topic you maybe don't remember that patent suggested also other alcohol than Glycerol

I did manage to dissolve 1.6g Salicylic acid in 500ml solution at under 30 degree Celsius but it took at least several hours.