New FX-55 Developer

[Gerald C Koch]

If this is true, Kodak could extend the working life of Xtol by adding a chelating agent but they have not.
The shelf life of Xtol in part full bottles is at least 2 months:
http://www.kodak.com/global/en/professional/support/techPubs/j109/j109.pdf

Ah, but Xtol does contain a chelating agent pentetic acid pentasodium salt or as it is more commonly referred to as DTPA, diethylene triamine pentaacetic acid. Check the MSDS for Xtol. For a description of what this chemical does see the following http://en.wikipedia.org/wiki/Pentetic_acid. In Xtol it serves a dual purpose. It not only slows the Fenton reaction but also prevents calcium ions from precipitating when hard water is used.

Not all chelating agents are suitable for slowing the Fenton reaction. Some like EDTA actually speed up the rate. Since no chelating agent is 100% effective (there is always some unchelated metal ion present) the Fenton reaction can only be slowed and not stopped completely.

 

[Alan Johnson]

Ryuji noted DTPA does not inactivate redox catalysis, see under "Chelating Iron":
http://web.archive.org/web/20090515222253/http://silvergrain.com/labs/Ascorbate_Developers
If it was as serious a problem as you imply they could add a chelating agent to Xtol that does work.

 

[Gerald C Koch]

Ryuji noted DTPA does not inactivate redox catalysis, see under "Chelating Iron":
http://web.archive.org/web/20090515222253/http://silvergrain.com/labs/Ascorbate_Developers
If it was as serious a problem as you imply they could add a chelating agent to Xtol that does work.

Not completely true, this is where one must read carefully what Ryuji says. "Eastman Kodak used chelator called DTPA (diethylenetriaminepentaacetic acid) in an attempt to chelate the transition metal ions. The DTPA cannot inactivate the redox catalysis of iron regardless of the amount added. However, if the ration of DTPA:iron is very high, the kinetics of the overall process is slowed down compared to the solution without any DTPA. One problem is that DTPA binds with other metals, including calcium and magnesium found in water supply, and therefore the effective amount of DTPA present in the working developer solution can be significantly lowered if hard water is used to mix the developer." Emphasis as underlining added.

This is probably why Kodak used so much 1-5% of DTPA in Xtol. an unusually high amount. While a chelating agent is not mentioned for other Kodak products such as D-76 or Dektol they surely must contain one probably DTPA. The MSDS for these products does not have to list most ingredients less than 1% unless they are particularly hazardous.

 

[Alan Johnson]

Yes.
Possibly Ryuji's work contributed to the Eco-Pro developers.
The Eco-Pro film developer has pentasodium DTPA and the print developer has triethanolamine.
This agrees with your comments to the effect that DTPA in Xtol is adequate, Eco-Pro film developer composition follows Xtol, not Ryuji's research apparent suggestion that DTPA is not good enough.
I had some of this FX-50 which needed much longer times than recommended in the instructions, nobody got around to modify this to slow oxidation, it remains a possibility.

 

[Gerald C Koch]

Ryuji once mentioned that he had found a chelating agent that was more effective than salicylic acid and that was readily available and reasonable in price. Unfortunately he never divulged its name. But salicylic acid is cheap and can even be made easily from aspirin tablets.

 

[Alan Johnson]

Actually, IIRC, the problem with FX-50 was not that it oxidized after it had been used for a while, as might be explained by the Fenton reaction, but that the stuff from the new just opened sealed bottle took much longer to develop film than it should have according to the instructions.
It may have been a bad batch or the plastic bottles may not have been impermeable.

 

[Roger Walker]

There was a recent thread about FX-50 developer at the (there was a url link here which no longer exists), but this week's Amateur Photographer magazine has an article by Geoffrey Crawley on his new FX-55 developer.

He has chosen to waive his copyright on this as long as Amateur Photographer magazine is mentioned as the source, so here goes:

Part A
Potassium Carbonate: 20g
Sodium Bicarbonate: 1.5g
Sodium Sulphite: 25g
Sodium Metabisulphite: 12g
Water to 1,000ml and dilute 1:9 for the working solution. Before use add B to the diluted 1:9 diluted A solution to form the working strength developer.

Part B
Sodium L-ascorbate: 1.3g
Phenidone: 100mg (0.1g)

 

[Roger Walker]

There was a recent thread about FX-50 developer at the (there was a url link here which no longer exists), but this week's Amateur Photographer magazine has an article by Geoffrey Crawley on his new FX-55 developer.

He has chosen to waive his copyright on this as long as Amateur Photographer magazine is mentioned as the source, so here goes:

Part A
Potassium Carbonate: 20g
Sodium Bicarbonate: 1.5g
Sodium Sulphite: 25g
Sodium Metabisulphite: 12g
Water to 1,000ml and dilute 1:9 for the working solution. Before use add B to the diluted 1:9 diluted A solution to form the working strength developer.

Part B
Sodium L-ascorbate: 1.3g
Phenidone: 100mg (0.1g)

 

[Roger Walker]

Peter, can you tell me where you obtained SODIUM L-ASCORBATE? From three companies, one company didn’t have it, one is asking $50 for 100g., and the last company is asking $100.00 for 100g; less shipping. This probably the most expensive developer from it from scratch. Do you have some unusual source for getting this chemical? I guess it must have some buffering quality instead of using health store vitamin C powder or ascorbic acid???

 

[Alan Johnson]

You can buy it on ebay, the food grade is a health supplement. Search for sodium ascorbate.

 

[removedacct3]

Or, as an alternative, have a look at this discussion: https://www.photrio.com/forum/threads/ascorbic-ascorbate-conversion-ratio.43042/

 

[Fluidphoto]

I've been using the food grade stuff and it's been giving me great results.

 

[craigclu]

I had this in my spreadsheet records and didn't record its source. An alternate B solution for FX-55.

Alternate Part B
Phenidone	1​	g
TEA	10​	g
Ascorbic Acid	12​	g
Propylene Glycol to	100​	ml

 

[ruilourosa]

This part B version works indeed. Add 10 or 15% to the developing time.

 

[removedacct3]

I had this in my spreadsheet records and didn't record its source. An alternate B solution for FX-55.

[TABLE=collapse]

Alternate Part B












Phenidone

1​

g


TEA

10​

g


Ascorbic Acid

12​

g


Propylene Glycol to

100​

ml

[/TABLE]

Your source was probably: https://www.photrio.com/forum/threads/new-fx-55-developer.41801/#post-597737

 

[Roger Walker]

Your source was probably: https://www.photrio.com/forum/threads/new-fx-55-developer.41801/#post-597737

Thank you very much, I found it, as you said on EBay. I thought it was vitamin C, but the “L” prefix had me ponder as to whether there was some dangling molecule making it incompatible with the formula. Not a chemist and there is no harm in asking. Thanks again!

 

[pentaxuser]

Having re-read almost the whole of this old thread I feel that the video I present below and the questions and answers attached to it are worth a look. The presenter is a guy called John Finch and his website is Pictorial Planet



I hope this helps. His website is worth a look as well as his videos

pentaxuser

 

[JPD]

Thank you very much, I found it, as you said on EBay. I thought it was vitamin C, but the “L” prefix had me ponder as to whether there was some dangling molecule making it incompatible with the formula. Not a chemist and there is no harm in asking. Thanks again!

Sodium L-ascorbate is a salt of Ascorbic acid, so not the same thing. https://en.wikipedia.org/wiki/Sodium_ascorbate

Both the acid and ascorbate count as Vitamin C, but they have very different pH in solution.

Sodium L-ascorbate is the same as Sodium ascorbate: https://commonchemistry.cas.org/detail?cas_rn=134-03-2

 

[schyter]

I Can get the same pH by using ascorbic acid instead of sodium ascorbate by decreasing the amount? (1.3gr sodium ascorbate X 0.889 = 1.1557gr ascorbic acid)

 

[koraks]

I Can get the same pH by using ascorbic acid instead of sodium ascorbate by decreasing the amount? (1.3gr sodium ascorbate X 0.889 = 1.1557gr ascorbic acid)

Keep in mind that the ascorbate is one of the two developing agents. Reducing its concentration will affect developer activity.
If you want to use ascorbic acid instead of ascorbate, you could for instance adjust the bath A. When A and B are mixed with water, the ascorbic acid will convert to ascorbate since it'll react with some of the carbonate in bath A. So either use a little more of part A when mixing the developer, or adjust the concentration of carbonate in concentrate A. Since concentrate A isn't just carbonate, but in fact a carbonate/bicarbonate buffer, working out how to modify concentrate A so that you can substitute ascorbic acid for ascorbate in concentrate B isn't entirely straightforward.

Frankly, I'd suggest just purchasing some ascorbate and mix the formula as it's given.

 

[schyter]

Francamente, suggerirei semplicemente di acquistare un po' di ascorbato e di mescolare la formula così come viene fornita.

...... I have only ascorbic acid in the house....

 

[koraks]

Yes, I suspected this. That's why I suggested to purchase/buy some ascorbate to resolve that situation, because that's really the easiest solution. The only drawback is that you'll have to wait a bit for the chemistry to arrive. But once it does, you can proceed in a simple and straightforward fashion.

There are several ways to make this work with ascorbic acid. Maybe someone else will go through the chemistry with you on this. The options will include the adjustment of concentrate A along the lines I mentioned. As said, it'll turn into a fairly complex buffer situation where things like mixing order suddenly potentially becoming important. Alternatively, drastically modifying concentrate B can also work, and would be more straightforward. It would involve taking out the ascorbate from concentrate B and adding a concentrate C which you can make with ascorbic acid and e.g. sodium hydroxide to turn that into ascorbate. All it takes is calculating the amount of hydroxide you need to convert a given amount of ascorbic acid into ascorbate, and you'll have to deal with a three-part developer instead of a two-part mix. Of course, in a similar vein, you could make an ascorbate concentrate from your ascorbic acid and some hydroxide, and then crystallize out the ascorbate by evaporation. It'll take some time and the end result won't be pure, so it would take you logically back to square one - consider buying some ascorbate.

 

[lamerko]

Does it really matter whether it will be ascorbate or ascorbic acid neutralized to a particular pH?

 

[koraks]

Does it really matter whether it will be ascorbate or ascorbic acid neutralized to a particular pH?

Depends. When using ascorbic acid, this will react with some of the carbonate when mixing the developer. Hence, some carbonate will be lost, which changes the set point of the carbonate/bicarbonate buffer. As a result, the pH of the developer will shift down a little, rendering it less active. How significant the difference will be? I don't know.

 

[Don_ih]

using ascorbic acid

See these quotes:

B solution comprised of 12 grams ascorbic acid and 1 gram phenidone ... will use up 0.6 grams of sodium bicarbonate in becoming 1.3 g sodium ascorbate and 0.1 grams of phenidone plus carbonic acid, which acid becomes water and CO2. ...
The difference between this solution and Crawley's will be 0.6 grams of sodium bicarbonate. Increasing the amount of the bicarbonate in the A stock solution by 6 grams should take out the difference...

I forgot that he had used potassium. 4.3 more grams of potassium carbonate would get you potassium ascorbate in the required molecular proportions.

So, according to him, bump up potassium carbonate by 4.3 grams in A and use 1.2 grams ascorbic acid in B. (The 12g in the quote comes from the B "stock solution" Gainer was talking about)