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Alan Johnson
11-21-2011, 04:33 PM
Some comments from Ryuji Suzuki on the effects of salicylic acid and TEA in this thread:
http://www.apug.org/forums/archive/index.php/t-47390.html
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
11-21-2011, 05:24 PM
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
11-21-2011, 07:49 PM
Some comments from Ryuji Suzuki on the effects of salicylic acid and TEA in this thread:
http://www.apug.org/forums/archive/index.php/t-47390.html
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
11-21-2011, 09:35 PM
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%20agents.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
11-21-2011, 11:00 PM
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.

Photo Engineer
11-22-2011, 10:39 AM
Lowering of pH due to lack of buffer capacity can lower contrast overall, lower Dmax, or increase edge effects in borders between objects of different density.

It depends on film and developer composition.

PE

Michael R 1974
11-22-2011, 11:55 AM
In the presence of a relatively high amount of sulfite the low activity would also tend to decrease sharpness/reduce graininess, wouldn't it?

I don't know, as a substitute for XTOL, this home brew formula seems inferior in all respects.

Photo Engineer
11-22-2011, 12:04 PM
Sulfite at this level tends to act as a mile silver halide solvent much as it does in D-76. As we all know, it is also a stabilizer (antioxidant) and a mild alkali or a weak base.

PE

Michael R 1974
11-22-2011, 12:10 PM
But if the pH, and therefore activity is low enough the film spends a significantly longer amount of time in contact with the sulfite. I'm thinking here of how D25 works compared to D23, although they both have more sulfite and don't use phenidone.

Am I wrong in thinking the 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

...would be a very low energy developer? This seems almost like a POTA variant with lower pH.

Photo Engineer
11-22-2011, 02:06 PM
It looks like D-76 with the HQ and Metol replaced by the Phenidone and AA. IDK. There is no great synergy between P and AA but there is between Metol and HQ which is what makes it work. Try it. I suspect again it will depend on film and will need some tinkering. These things always do.

We went through many variants for TF-5 and Liquidol to come up with final formulas that performed as they now do.

PE

BradS
11-22-2011, 02:08 PM
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

Mark Overton

Is the ascorbic acid going to act as a developing agent at this pH ? I don't think so.

BradS
11-22-2011, 02:14 PM
You must remember that there are trade off situations. The developers at Kodak cost millions of dollars to develop. All others were done on a shoestring by comparison.
(...snip...)
PE

I think this is why I keep coming back to plain vanilla D-76. There is a reason that it has been around so long and ther eis a reason that virtually every commercially viable producer of developers fro B&W films has offered an "equivalent" to D-76. Similar ideas apply to XTOL (and maybe even Dektol?).

Photo Engineer
11-22-2011, 06:06 PM
There are several variations on Dektol that offer different degrees of similarity and improvement. Same thing as with D76.

PE

albada
11-22-2011, 06:54 PM
But if the pH, and therefore activity is low enough the film spends a significantly longer amount of time in contact with the sulfite. I'm thinking here of how D25 works compared to D23, although they both have more sulfite and don't use phenidone.

Am I wrong in thinking the 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

...would be a very low energy developer? This seems almost like a POTA variant with lower pH.

Keep in mind that this formula is an attempt to simplify Ryuji Suzuki's DS-10, which has the above amounts of phenidone and sulfite. It likewise has a pH of 8.00, but it uses different acids/alkalies to achieve 8.00, whereas I increased the ascorbic acid to do so. So with the same pH and sulfite, and equal or greater quantities of same developers present, I'm hoping this formula will behave like DS-10. Although PE warns me (in different words) that things don't always (even usually?) work as expected.:confused:

I got the order with Photo Formulary straightened out, I'll soon have some ascorbic acid for tinkering with this.

Mark Overton

Gerald C Koch
11-23-2011, 11:23 AM
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

I think that Ryuji was being conservative at this point because he hadn't finished testing for the developer's storage life. The Stability Constant for the iron-salicylate complex is 6.55 which I think is adequate.

Gerald C Koch
11-23-2011, 11:26 AM
Solubility of Salicylic acid in water is given here as ~2g/L
http://en.wikipedia.org/wiki/Salicylic_acid

In DS-10 you are not dealing with pure water but with an alkaline solution which will increase the solubility.

Gerald C Koch
11-23-2011, 11:32 AM
I like removing ingredients while only half-knowing what I'm doing. :)
Mark Overton

Saying that a formula has too many ingredients is like saying that Mozart's music has too many notes. :) In a developer each of the ingredients has a purpose. Remove things at your own peril. You cannot remove the TEA or salicylic acid without changing the developer's pH among with other effects.

nworth
11-23-2011, 12:54 PM
I wonder what a little bit of EDTA-Na would do for stability.

Photo Engineer
11-23-2011, 01:39 PM
I would like to see the complexation constants for Ferric EDTA and Ferric Salicylate in the same medium and at the same concentration.

I can't seem to find this information yet.

PE

Gerald C Koch
11-23-2011, 02:52 PM
I came across a list www.coldcure.com/html/stability_constants.html which contained mostly compounds involved in human physiology like amino acids but which also contained the following

ferric salicylate 16.35 ferrous salicylate 6.55
ferric EDTA 25.7 ferrous EDTA 14.3
ferric NTA 15.87 ferrous NTA 8.84

salicylate constants seems to roughly comparable to those of NTA in stability.