Improved version of DS-10 by Ryuji Suzuki?

[albada]

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 (there was a url link here which no longer exists)). 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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

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]

.....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]

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]

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]

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]

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]

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]

Solubility of Salicylic acid in water is given here as ~2g/L
http://en.wikipedia.org/wiki/Salicylic_acid

 

[albada]

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

 

[Alan Johnson]

Some comments from Ryuji Suzuki on the effects of salicylic acid and TEA in this thread:
(there was a url link here which no longer exists)
I believe only the print developer ever went into production.It is more exposed to oxidation and the effects of the iron and copper likely more than they would be with the low pH DS-10.
I suggest recalculate your formula with about 1g/L salicylic acid.IIRC from making DS-12, that much dissolves OK.

 

[Photo Engineer]

The Sulfite is going to either be a superb silver halide solvent or a superb pseudo alkali, but not really both in this formula. It needs something else IMHO and Ryuji seems to have worked out what is best for these ingredients. I'm not saying that your idea won't work, just that it may be quite different than you expect in both activity and pH, and that you may have to tinker with it a bit.

Let us know how the pH turns out.

PE

 

[albada]

Some comments from Ryuji Suzuki on the effects of salicylic acid and TEA in this thread:
(there was a url link here which no longer exists)
I believe only the print developer ever went into production.It is more exposed to oxidation and the effects of the iron and copper likely more than they would be with the low pH DS-10.
I suggest recalculate your formula with about 1g/L salicylic acid.IIRC from making DS-12, that much dissolves OK.

Thanks for the link with Ryuji's rationale for the TEA and salicylic acid. Here are some telling fragments:

"the main purpose of TEA in DS-14 is iron and copper chelator"​

"The quantities of TEA and salicylic acid are rather small, but you'll see improved keeping properties"​

Based on his posting, TEA and salicylic acid are solely for chelation and scavenging radicals -- both to improve storage. I'm thinking that for a mix-as-you-use developer, dropping both of these may be safe.

The Sulfite is going to either be a superb silver halide solvent or a superb pseudo alkali, but not really both in this formula

This is interesting, and I guess we can only find out by trying. Easy enough once the chems arrive. No email-confirmation from Photo Formulary today; did they take today off?

I remember reading a posting somewhere that tests showed that having too much ascorbate (ascorbic acid?) in a developer is harmless. If so, we can add extra to drop the pH to 8.0. That means we can also delete the boric acid, resulting in this simple formula:

Water ................................... 750 ml
Phenidone ............................ 0.15 g developer
Ascorbic Acid ....................... 14.3 g developer, and adjust pH to 8.00
Sodium Sulfite (anhydrous) .... 75 g alkali and halide-solvent
Water to make ...................... 1 L

​

I note that this formula is similar to Instant Mytol (by Jordan; see http://www.photosensitive.ca/wp/easy-film-developers)

11.5 g ascorbic acid (same molar concentration of ascorbate as MYTOL)
0.15 g phenidone
60 g sodium sulfite (anhydrous)
13.4 ml triethanolamine or 7 g sodium metaborate (“Kodalk”)

​

All this looks nice on paper, but I don't trust my pH-calculations, and PE's warnings about surprises with pH and activity are going to be on my mind...

Mark Overton

 

[Photo Engineer]

You must remember that there are tread off situations. The developers at Kodak cost millions of dollars to develop. All others were done on a shoestring by comparison.

As for chelating ability of TEA, well in order of ability, you may want to look at NTA http://chemicalland21.com/specialtychem/perchem/chelating agents.htm for information. NTA is the fully oxidized form of TEA and is a superb chelating agent used in Kodak C41 bleach 3. TEA by comparison is a pale equivalent that just barely qualifies as a chelating agent.

PE

 

[Alan Johnson]

The interesting question has been raised "why bother to buffer?"
For each atom of metallic silver formed a hydrogen ion is produced which will lower the pH at the grain surface and slow development.The effect of this I do not know.