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albada
11-20-2011, 10:59 AM
Reports say that DS-10, created by Ryuji Suzuki, is comparable to XTOL. A few years ago, Ryuji said that he had improved DS-10, and implied that he would publicize the formula (see http://www.apug.org/forums/archive/index.php/t-25194.html). Did he ever make that improved formula public? His web-site no longer has his formulas, which is a pity.

Here's the formula of DS-10 from digitaltruth.com. I don't know if this is the improved formula:

Water ......................... 750 ml
Dimezone S .................... 0.15 g
Ascorbic Acid ................. 8 g
Boric Acid .................... 4 g (Ryuji: Use 2g to match XTOL's dev-time and pH of 8.2. Called "DS-10X")
Salicylic Acid ................ 1 g
Sodium Sulfite (anhydrous) .... 75 g
Triethanolamine, 99% .......... 10 ml (TEA)
Water to make ................. 1 L

Thanks,

Mark Overton

Gerald C Koch
11-20-2011, 11:30 AM
I am not aware of any published formula for an improved version of DS-10. RS sold his formulas to a company who was manufacturing them under their own name. IIRC, the improved version was said to use a chelating agent different from the salicylic acid/triethanolmine mixture.

albada
11-20-2011, 12:19 PM
I am not aware of any published formula for an improved version of DS-10. RS sold his formulas to a company who was manufacturing them under their own name. IIRC, the improved version was said to use a chelating agent different from the salicylic acid/triethanolmine mixture.

I thought the salicylic acid was a chelating agent (for iron?), but I'm wondering why the TEA is in there, considering that there's plenty of alkali in the 75 g of sulfite. Is TEA also a chelating agent for something? Or could the TEA also perform a role in development?

I'm wondering if the salicylic and TEA can be dropped if distilled water is used.

Mark Overton

brucemuir
11-20-2011, 12:37 PM
Would someone be so kind as to describe the action/function of a "chelating agent"?

Or perhaps direct me to somewhere I could read about this. I did look it up once and the wiki wasn't to informative or maybe I wasn't understanding.

I ususally see it in relation to color C41 process.

Gerald C Koch
11-20-2011, 02:52 PM
I thought the salicylic acid was a chelating agent (for iron?), but I'm wondering why the TEA is in there, considering that there's plenty of alkali in the 75 g of sulfite. Is TEA also a chelating agent for something? Or could the TEA also perform a role in development?

I'm wondering if the salicylic and TEA can be dropped if distilled water is used.

Mark Overton

The TEA is also a chelating agent and with the salicylic acid seems to increase the chelation of iron.

Iron is a common impurity of many inorganic chemicals and so you cannot get around not using a chelating agent just by mixing the developer with distilled water. Salicylic acid can be obtained from many compounding pharmacies. It shouldn't be expensive. I purchased 250 g a few years ago for $1o. TEA can be purchased from such locations as www.chemistrystore.com.

Photo Engineer
11-20-2011, 03:36 PM
TEA here functions as an alkali. TEA is so weak as a chelating agent, it is not considered one as such and is often used in combination with a "real" chelating agent such as EDTA. A chelating agent can be considered a material which combines with specific metal ions and reduces their activity or prevents side reactions from taking place. A good place to learn about TEA and chelating agents is via Wikipedia.

The Sulfite is primarily a silver halide solvent and acts in a fashion similar to its role in D-76.

PE

Alan Johnson
11-20-2011, 04:26 PM
Here is the original formula from the former site:

DS-10
water......................................700ml
sodium sulfite,anhydrous.............75g
triethanolamine,99%...................10ml
ascorbic acid.............................8.0g
Dimezone S...............................0.15g
salicylic acid..............................1.0g
boric acid..................................4.0g
water to make............................1.0 liter
target pH...................................8.00 +/- 0.05

Digitaltruth differs only wrt an insignificant change in the initial amount of water used.

albada
11-20-2011, 06:48 PM
TEA here functions as an alkali. TEA is so weak as a chelating agent, it is not considered one as such and is often used in combination with a "real" chelating agent such as EDTA. A chelating agent can be considered a material which combines with specific metal ions and reduces their activity or prevents side reactions from taking place. A good place to learn about TEA and chelating agents is via Wikipedia.
PE

Everyone, thanks for the interesting information.
So the TEA isn't primarily for chelation/sequestration, which makes me wonder why two alkalis are needed (TEA and sulfite).
Do you suppose the TEA is needed to convert the ascorbic acid into ascorbate?
If so, could sodium bicarbonate be used instead?
Hmm, come to think of it, I'm not even sure that the ascorbic acid needs to be converted to ascorbate to be super-additive with phenidone.

I know these additional chems are easy to buy, but I'm trying to avoid turning into a chemical-collector. :)

Thanks,

Mark Overton

albada
11-20-2011, 07:07 PM
The TEA is also a chelating agent and with the salicylic acid seems to increase the chelation of iron.


As PE implied in his response, you're saying that TEA and salicylic acid have a super-additive-like effect in chelating iron?

I did a google search for sequestering iron, and it appears that there are few methods of dealing with it. EDTA (which I think is in XTOL) and sodium tripolyphosphate (STP, not TSP) are a couple of choices.

Mark Overton

Photo Engineer
11-20-2011, 07:15 PM
The two bases may be to adjust to the proper pH, but I see that the formulas above differ in pH with no explanation. In any event, use of 2 bases is not that unusual. I don't rule out chelation from TEA, just not as its primary function doe to its weak power as a chelating agent compared to its strong power as a base.

Borate may offer some buffer capacity. Salicylic Acid is a weak chelating agent as well. It is claimed by some to offer protection to Ascorbates from oxidation by metal salts.

Salsylic

albada
11-20-2011, 08:41 PM
The two bases may be to adjust to the proper pH, but I see that the formulas above differ in pH with no explanation. In any event, use of 2 bases is not that unusual. I don't rule out chelation from TEA, just not as its primary function doe to its weak power as a chelating agent compared to its strong power as a base.

Borate may offer some buffer capacity. Salicylic Acid is a weak chelating agent as well. It is claimed by some to offer protection to Ascorbates from oxidation by metal salts.


Hmm, so the TEA and boric acid can form a buffer-system. I didn't know that. Now things are coming together for me. Thanks for the help!

BTW, I wonder how effective the protection provided by TEA and salicylic acid really is. Ryuji himself noted that DS-10 stock only lasts two weeks.

Here's an abstract of an article about salicylic acid working in conjunction with ascorbate in oxidizing/chelating iron:
http://www.ncbi.nlm.nih.gov/pubmed/9575412
I wonder if this is the article which motivated Ryuji to investigate salicylic acid...

Mark Overton

Photo Engineer
11-20-2011, 10:14 PM
There are several patents on this subject of Salicylic acid as an antioxidant (so to speak), but there are reported to be better compounds. Ryuji himself, here on APUG, stated that IIRC.

As for a "buffer", well usually you use Carbonate and Bicarbonate as a buffer pair as an example, so my comment was only an analogy. Maybe a pH stabilizer or assisting agent would be better.

PE

john_s
11-21-2011, 05:40 AM
.....Ryuji himself noted that DS-10 stock only lasts two weeks....

Mark Overton

That's not very long given that it has quite a few more ingredients than most developers. Xtol lasts a lot longer than that.

Gerald C Koch
11-21-2011, 11:21 AM
I am doubtful about the two week life for DS-10 and I wish that the poster had substantiated his claim. If this were true then what would be the point of using any chelating agent. RS stated that his print developer (also ascorbate based, and similar to DS-10) lasted for more than 6 months in his slot processor. I personally have used DS-10 for many weeks without problem and found that it works as well as Xtol. RS was seaching for a better chelating agent but was encountering problems with price and availability. But he was also reasonably satisfied with the salicylic acid/TEA combination.

BTW, you can't use just any chelating agent in ascobate developers. Most agents actually increase the rate of oxidation. An example of a bad agent is EDTA.

Photo Engineer
11-21-2011, 11:28 AM
I suggest that those interested run some tray and bottle keeping tests then for both the print and film developers, and compare them with a references such as D-76 and Dektol.

PE

albada
11-21-2011, 11:43 AM
That's not very long given that it has quite a few more ingredients than most developers. Xtol lasts a lot longer than that.

Yes! So DS-10 will be used mostly mix-as-you-go, making preservatives unnecessary. So I'd like to simplify the formula. Also, I would use it stock (undiluted) with distilled water, so I probably won't need a buffer-pair in it to maintain pH.

Here's an online pH-calculator I've been using: http://www.webqc.org/phsolver.php

Let's start with the 8 grams of ascorbic acid and 75 grams of sulfite in DS-10. The calculator's inputs are pKa/b and concentration:


Ascorbic pKa1=4.10 pKa2=11.6 c=0.045424
Sulfite pKb=6.8 c=0.5950

This gives a pH of 8.28. Let's add Ryuji's 1 gram of salicylic acid to help chelate iron:


Ascorbic pKa1=4.10 pKa2=11.6 c=0.045424
Sulfite pKb=6.8 c=0.5950
Salicylic pKa=2.97 c=0.007240

Now the pH is 8.21. Let's boost the salicylic acid to 5 grams:


Ascorbic pKa1=4.10 pKa2=11.6 c=0.045424
Sulfite pKb=6.8 c=0.5950
Salicylic pKa=2.97 c=0.0362

That drops the pH to 8.00, which is the target pH of DS-10. The corresponding formula is:
.

Water ................................... 750 ml
Phenidone ............................. 0.15 g
Ascorbic Acid ........................ 8 g
Salicylic Acid ........................ 5 g
Sodium Sulfite (anhydrous) .... 75 g
Water to make ...................... 1 L

.
Well, that removes the TEA and the (hard to dissolve) boric acid, which I'm hoping were just a buffer-pair.
Anyone want to take a guess how well this will work?
I've ordered the additional chems from PhotoFormulary.com, so I'll soon be experimenting with this...

Mark Overton

albada
11-21-2011, 12:07 PM
I am doubtful about the two week life for DS-10 and I wish that the poster had substantiated his claim. If this were true then what would be the point of using any chelating agent.

Ryuji said in a pure-silver posting, "At this point I do not recommend to store DS-10 for any more than a couple of weeks." Farther down in that posting, Ryuji says, "At this point, I mix DS-10 as I use."

Here's the link: http://www.freelists.org/post/pure-silver/DS10-information,1

So yes, it makes one question the addition of chemicals for preservation.

Mark Overton

Photo Engineer
11-21-2011, 12:45 PM
Mark;

I hope you have a good pH meter. Also, note that the two formulas above have 2 different pH aims.

You are in a very iffy position in that developer.

Best luck anyhow.

PE

Alan Johnson
11-21-2011, 03:31 PM
Solubility of Salicylic acid in water is given here as ~2g/L
http://en.wikipedia.org/wiki/Salicylic_acid

albada
11-21-2011, 04:25 PM
Solubility of Salicylic acid in water is given here as ~2g/L
http://en.wikipedia.org/wiki/Salicylic_acid

Yikes! Thanks for catching that mistake! 5 g/L of salicylic acid obviously ain't gonna happen.


You are in a very iffy position in that developer.

I like removing ingredients while only half-knowing what I'm doing. :)
Is the weakness the reliance on sulfite as the sole alkali? Or losing some chelation provided by TEA? Or altering the conversion of ascorbic acid into ascorbate?
Or all of the above? :)/2

Mark Overton