Experiences with Vitamin C developers please

[Gerald C Koch]

Ummm ...

Salicylic acid does not dissolve in distilled water at 20C ...

I placed a very light powdering of the acid on top of my working solution prior to adding the stock concentrate. I put the beaker onto a magnetic stirrer for a good 5 mins ... it is just a precipitate !!

Why do I feel I am going precisely nowhere ?

Salicylic acid is slightly soluble in water at least enough to get a 1% solution. Curiously it is less soluble in hot water than cold. It is more soluble in alkaline solutions. It should be easily soluble in the developer concentrate containing TEA. The concentration should be ~0.2 g/l in the working strength (diluted) developer.

Some chemicals are not easily wet by water and tend to float on the surface rather than dissolve. Powdered boric acid is another example of this. Sometimes it helps to make a paste with a small amount of water to get the chemical wet before adding the additional liquid.

 

[Gerald C Koch]

There is a report of problems with concentrate apparently made with 85% TEA:
http://photo.net/black-and-white-photo-film-processing-forum/00crck

Technical grade TEA is 85% TEA and ~15 % DEA and produces a higher pH developer. This may be OK for certain formulations but cause excessive development in others. Cosmetic grade TEA is 99 to 100% pure. Always use the grade that the formula specifies.

 

[swmcl]

Hi Gerald,

Yes as far as I know, and I tried to make certain, I am using 99-100% TEA. I'm not sure I achieved anything with the last film. I think salicylic acid dissolves in glycol quite well.

I certainly didn't have 0.2 g/l in the working solution. That would be 0.06g in 300ml. I had a poofteenth of a gram. Too small to measure I would think.

I do have the scales to go down to 1 milligram so I could do the 60mg for 300ml but ... if I couldn't get a poofteenth to dissolve there wasn't much point doing any more !

Would it be better to do a test with say a drop or two of TEA on a spoon and try to get the 60mg to dissolve into that ? The problem there is that I am only using 1.75ml of stock for this working solution. I can't use too much TEA trying to get it to dissolve. Otherwise I could try a drop or two of glycol on a spoon ?!

My chemistry doesn't remember how if I get something to dissolve into a solvent (eg. glycol) that when it gets diluted into water the acid doesn't precipitate out of solution but anyways ...

If you knw that either using a TEA spoon ful or a glycol spoon ful would do the trick then I'll proceed with that.

The other test for me to do is to make up a working solution that has an amount of ascorbic added to the working solution just prior to adding the developer.

So that is still two tests.

I'll go and start the densitometer and measure my results.

Cheers,

Steve

 

[swmcl]

Results:

First run - gradient is around 0.3166
Second run with salicylic acid - gradient is around 0.3388 using the same techniques.

So a marginally better result but nothing like the 0.48 I am expecting. The film speed is shockingly low at about ISO 16 on the second run.

I will say the stock solution is a very weak straw colour as expected at the start and the colour after development is a deep straw. So it is as normal.

The second run was done using a glass beaker to mix the pre-wash and another for the developer.

Cheers,

 

[Rudeofus]

A few things come to my mind:

1. I don't understand why your Salicylic Acid gives you so much trouble dissolving at 0.2 g/l. Ryuji Suzuki's DS-10 uses 1 g/l and I don't remember having difficulties dissolving it. Wikipedia for Salicylic Acid reports solubility of 2.48 g/l at room temperature. If you can't dissolve 0.2 g/l you should ask your supplier what they really gave you.
2. You added an acid which will lower the activity of your developer, yet you got higher contrast. This tells me that Salicylic Acid cured one problem (iron catalyzed decay of Ascorbic Acid) but opened another: Ascorbic Acid that decayed in your concentrate turns into more acidic compounds, which lower pH and thereby reduce developer activity yet more. You can work around this by adding more TEA to your working solution. Start in increments of 0.5 ml/l and ramp up until you see base fog. This should return speed to normal.
3. If you then still have too little contrast, add more Ascorbic Acid until contrast matches your expectations.

This whole list sounds like you might as well mix your developer from scratch, but things will turn out less complicated than it sounds right now. The Salicylic Acid (once you really have Salicylic Acid) can go straight into the base concentrate, and you can make a small batch of concentrate from TEA and Ascorbic Acid, of which you add more and more as your other stock concentrate gets older.

 

[Alan Johnson]

Results:

First run - gradient is around 0.3166
Second run with salicylic acid - gradient is around 0.3388 using the same techniques.

So a marginally better result but nothing like the 0.48 I am expecting. The film speed is shockingly low at about ISO 16 on the second run.

I will say the stock solution is a very weak straw colour as expected at the start and the colour after development is a deep straw. So it is as normal.

The second run was done using a glass beaker to mix the pre-wash and another for the developer.

Cheers,

You are not the first to find the Fenton reaction has no measurable effect in the short time the working solution is used, see post 305 here:
(there was a url link here which no longer exists)
IMO it would be preferable to first verify that the concentrate is OK by developing a 35mm or 120 film in a working solution from this.Hundreds of other users can't be wrong.
If it is OK, I repeat that you are likely seeing the oxidation of Pyrogallol as mentioned by Sandy King.

 

[swmcl]

Alan,

I'm not sure how to go about the test of the concentrate that you suggest. I'm shooting a single sheet of 4x5 of FP4 at a time and processing it in a Jobo drum from the concentrate. I use a slow hand rotation on a Jobo roller base for all film development. How does processing a 35mm film make any difference ? You'll have to probably be very specific with me because I'm getting results very close to my original and I'm simple enough at times !

I thank you for the link. It tells me there would be no significant negative impact to adding salicylic acid to the stock TEA-based 510 Pyro concoction I think.

It also makes me aware of the fact that many others travel my road. All I ever wanted was to find an active Pyro developer that had a very good shelf life and was in one-part solution. If someone is aware of a shortcut or can strongly advise me to stop and get off this thing I'd appreciate it !

Rudeofus,

I have contacted New Directions and they assured me it was 100% active powder. Surely though if I mix salicylic into a little TEA before mixing it into the working solution this would work ... but I guess its changing two variables at once. So would I be better to mix salicylic into glycol (PG) rather than TEA ?

In the Ryuji Suzuki formulae with salicylic acid there is also listed TEA (eg. DS-10) I assume the salicylic is dissolved in the TEA prior to mixing into the whole brew ... The listed ingredients in the DS-10 are not in the order of the making then ...

Perhaps the salicylic acid (being a very fine powder) was needing to be mixed as a paste prior to mixing in water ? Anyway, I'm not sure the ferrous contents are an issue if they are meant to produce a purple product because even in the worst of times the solution was never purple.

I'm thinking I have degradation of the ascorbic in the stock. To prove this I'll need to complete another test with a pinch of ascorbic in the working solution. Why would I lose the ascorbic in the 100% TEA when it is under Nitrogen ? Am I going to lose ascorbic under every circumstance whether I put it in glycol by itself or whatever ? Will the 510 be better preserved in glycol rather than TEA thus necessitating a part B like Pyrocat-HD ?

Would it be helpful to make a note of the pH levels ? Or am I going to confuse myself even further ?

Cheers,

 

[Gerald C Koch]

The amount of ferrous ion needed to destroy ascorbic acid can be very small (a few milligrams or even less). Far too little to exhibit any purple coloration of the solution.

The Fenton reaction is a kinetic reation and the speed at which it occurs is dependent on the amount of iron or copper ions present. It is also dependent on the stability for the ion-chelate complex. Some chelating agents are more effective than others. The reaction can be slowed but never completely stopped. When I first started investigating ascorbate developers I had a batch of paper developer die overnight. That was without any chelating agent present.

The developing properties of ascorbic acid have been know for some decades. It is mentioned in Mason and in Glafkides. Three things conspired to make for its current popularity.

1. The reduction in price because of its increase in manufacture due to its popularity in the health food market.

2. A solution to its instability when used in developers.

3. The restriction of the use of hydroquinone particularly in the EU and a need for an acceptable substitute.

 

[Rudeofus]

I have contacted New Directions and they assured me it was 100% active powder.

When I bought my Salicylic Acid in some pharmacy, they at first assumed I wanted Aspirin, fortunately they asked be before filling the order. Either way, water solubility is a pretty much constant property of such a compound, and if your "Salicylic" doesn't dissolve in 1 g/l in tap water, then something is likely wrong. Can they give you a CAS number of the compound you got?

Surely though if I mix salicylic into a little TEA before mixing it into the working solution this would work ... but I guess its changing two variables at once. So would I be better to mix salicylic into glycol (PG) rather than TEA ?

You are correct, solving for two or more intermingled variables at once won't be easy, fortunately we don't have to do this. We can separate the variables, as described in my previous posting: first, with 0.5 g/l Salicylic Acid in solution we make sure that Ascorbic no longer decomposes in your working solution. Then you add alkali until film speed is restored, just to the point where fog becomes an issue. Finally you add Ascorbic Acid until contrast is where you want it.

In the Ryuji Suzuki formulae with salicylic acid there is also listed TEA (eg. DS-10) I assume the salicylic is dissolved in the TEA prior to mixing into the whole brew ... The listed ingredients in the DS-10 are not in the order of the making then ...

As far as I remember I had no problem dissolving them in the order given. See my comment above.

Would it be helpful to make a note of the pH levels ? Or am I going to confuse myself even further ?

A change in pH will tell you that something changed, and you can try to correlate a change in pH with a change in both behavior and remedy. The question remains, though, whether a regular pH measurement is less hassle than mixing a smaller batch of concentrate more often.

 

[Alan Johnson]

I'm not sure how to go about the test of the concentrate that you suggest. I'm shooting a single sheet of 4x5 of FP4 at a time and processing it in a Jobo drum from the concentrate. I use a slow hand rotation on a Jobo roller base for all film development. How does processing a 35mm film make any difference ?

Steve,
IMO itwould be useful to check your concentrate is OK by developing a 35mm/120 film in a Paterson-type tank and confirm that it gives good results using the time given for 510 Pyro:
http://www.digitaltruth.com/devchart.php?Film=&Developer=510-Pyro&mdc=Search&TempUnits=C
If the result is OK then the problem is not due to the concentrate but related to different oxidation of the developer in the Jobo compared to a Paterson-type tank.
If the result with the Paterson-type tank is not OK there is something wrong with your concentrate as the developing chart is usually quite accurate on times.

 

[swmcl]

Alan,

I originally started out by exposing and developing a number of 35mm rolls of FP4 in 510 Pyro. The tank I used was a Jobo 1510. I got a series of curves and tried to put it all into the Winplotter etc.

I think what you're saying is that the Jobo 3006 tank may be far less agitation due to the fact that there is no internal spool etc. to create a really strong oxidization... ?

I'm not sure what the difference between your 'Paterson-style' tank and a normal spooled Jobo tank would be as I only use Jobo but I'm guessing the tank you are referring to has no spool and is just one simple tube ?

If this is the case, the agitation differences between Jobo Expert tanks and the normal line of spooled tanks should be considered quite significant when using developers that oxidize rapidly.

Certainly, I can say that nothing looks out of place in my process. The colours of the liquids, the temps, the times etc are all as expected so maybe you are right. Perhaps I need to 'start again' in the expectation that the Expert tanks are creating less oxidation and agitation (certainly at my speed of 6 rpm by hand that is ...)

I have assumed that 6 rpm of a 1510 tank is going to be very similar to 6 rpm of an Expert 3006 ...

Steve

 

[swmcl]

I've gone back and looked at my previous results.

The 510 seems to go for quite a while before really taking off. The curves show a virtually exponential increase in activity after 5 mins. From other's experiences, the higher strength working solution is even worse. Part of my decision to use it at 1:200 was that it regulated the exponential to some extent.

The bad thing is too that after 'taking off' it levels out very quickly. It's as though there is a 'sweet spot' like running an engine with a tuned exhaust.

Have you seen this with other developers ?

To prove the agitation thing all I need do is develop for a really long time do I not ? Instead of 7 mins go 14 ... or 12 ? Rather than source a Paterson-type tank just for the test ...

If the developer is really shot then the increase in time won't change that much. If however, the developer is yet to hit the sweet spot then giving it time to do so will sort that out ...

One more sheet and no more buying of things. I like it.

 

[Alan Johnson]

I have always found that the times in the massive development chart are about right for inversion agitation of a tank with spool, using 3 inversions during about 10 seconds, each minute.If this procedure is followed it seems to me that if good negatives are obtained using the mdc times, the concentrate used to make the working solution must be OK.
With rotary processing the time is less,IIRC about 15%.
The mdc times for sheet film are given in the chart.If the concentrate is OK it appears the time should be between that given in the mdc and 15% less.

 

[Gerald C Koch]

The 510 seems to go for quite a while before really taking off. The curves show a virtually exponential increase in activity after 5 mins. From other's experiences, the higher strength working solution is even worse. Part of my decision to use it at 1:200 was that it regulated the exponential to some extent.

I seem to remember reading that ascorbic acid in the absence of sulfite has a long induction period. This would seem to fit with your data.

 

[swmcl]

The time for the Massive Development Chart for 510 Pyro @ 1:200 mentions a ISO of 64 for 7 minutes.

I am exposing for an ISO of 32 and also developing for 7 mins at the same dilution.

Although I feel somewhat small because of my oversight, I will extend my development to at least 9 mins and see what happens.

Cheers,

 

[sfaber17]

I finally worked on my 510 Pyro problems using iodine titrations. I found the Formulary ascorbic acid to be good. I tried to titrate the AA in the TEA, but it seem the TEA was reducing the I3- somewhat so it was hard to say, but it seems the AA in the TEA is OK. Next I titrated my pyro which was in glycerin and found it to be about half the concentration I thought it was. I was making my pyro from gallic acid, so I think I didn't have the expected yield. The pyro titration was a bit more difficult since it gets darker and darker from the oxidation products, but you can still see the starch endpoint. I'm assuming the pyro uses up 3 I3- ions. Hopefully the glycerin wasn't being oxidized. I guess I'll buy some pyro and try it. Maybe I'll try some experiments on decay of the AA over time in dilute solutions in distilled and lake michigan city water.

 

[sfaber17]

Here is that test of ascorbate oxidation with beakers of solution set out for 3.5 hours:
- City water from lake michigan vs.
- distilled water from stainless steel still

Each was a beaker of 50 ml with a conc. of about 1.8 and 1.2 g/liter of ascorbic acid respectively.
The city water had 79.8% of its ascorbic acid left, and the distilled had 98.2% left.
The test accuracy was a bit less than 1% error. Both water types were checked for possible initial reducing agents, but both had immediate endpoints, so they were both clean.
I was a bit surprised since the lake water is very clean and doesn't have much iron, but it
demonstrates the effect that has been discussed. It also seems that using stainless steel may not be a problem. I did not store the distilled water in SS however, it was just distilled with it.

 

[john_s]

.....I purchased 5 litres of TEA and various raw chemicals - a number of them at great shipping expense to Australia.....

Steve

I don't know where you are in Australia, but I'm in Melbourne and I ordered chemicals such as pyrocatechol and metol from Merck in Melbourne and picked them up myself. They were cheaper than Vanbar which is still good for bulk chemicals (but I don't know for how long as I don't think they're selling much these days).

 

[swmcl]

Thanks John for the info. I haven't heard of Merck before ... I wonder if they would do Pyrogallol ...

It is good to know there might be an alternative to Vanbar I do admit. I purchased a few chems from Bostick and Sullivan in the US who were great.

 

[cliveh]

I'm currently trying to standardise my workflow around a developer that has an amount of Vitamin C in it.Steve

Vitamin C is good for humans, but indifferent to aesthetics.

 

[swmcl]

Sfaber,

The general conclusion is that with ascorbic acid developers in particular, the best practice is to avoid stainless and use distilled, yes ? The reaction does take place albeit very slowly. Perhaps we could say that the Fenton reaction is something to be more aware of in cases of stand development where there is an extended development time ? I think maybe we could also say that adding a little salicylic acid to the main stock solution if possible is not harmful ... ?

I'd like to see your experiment with some salicylic acid in one of the beakers ...

 

[swmcl]

Results are in ...

To recap,

The first attempt shot at 32 ISO hand developed for 7 mins is a gradient of 0.3166 at one point in the graph. Using all the same settings, the second attempt had a very small amount of salicylic acid added and the gradient improved slightly to 0.3388.

The third attempt has a plain mix of developer without the salicylic acid for 9 mins. The gradient is 0.3888 which is still pretty poor.

Is it really the case that a Jobo 3006 for 9 mins is still not the same as a Jobo 1500 series tank at 7 mins using the same 6 rpm constant hand rotation ? I'm thinking to get the 0.47 gradient I might need to extend another 4-5 mins ?

This test has me back thinking something has gone awry with the developer. I just am struggling with the idea that the Jobo Expert tank would need up to double the time of the Jobo 1500 series tank.

Remember also that my times are now well in excess of the Massive Development chart for the 1:200 dilution.

I guess now the idea is to develop a sheet with an added pinch of ascorbic into the working solution ?

Cheers,

Steve

 

[sfaber17]

Steve, I tend to agree with others that the large surface area to volume ratio of the expert tank is causing pyro oxidation trouble, and since you are using distilled water, fenton reactions aren't a factor and adding salicylic acid isn't going to help. What is the volume you use for the expert tank and how many sheets are you doing? The other possibility is (since you said the color of the spent developer isn't that dark) is that you don't have enough developer volume for your film area.

This thread has been very useful. I just verified I'm using that no good Photographers Formulary
TEA that is 15% DEA. After I get some new, along with some new pyro, I"ll test it in my jobo, but I have a 2500 series reel for 4x5 and no expert drum. I need to try the slow speeds now.

Maybe the only way to get consistent results with rotary processing would be to add sulphite to tame the oxygen and perhaps use more C. I kind of like that approach with LSD-6, where you don't have to mess with that TEA. It is easy to weigh out some nice cheap Na ascorbate crystals and a little sulphite and add the touch of phenidone or dimesoneS from a solution in glycol or alcohol.
The Na ascorbate hydrolyzes to give you the basic pH along with the sulfite. Maybe if we add pyro, we would have something that would give pyro results and would be better for rotary processing.

 

[swmcl]

Sfaber,

I also asked for a special batch of 510 from Formulary. I complained like hell that he didn't use the right TEA. If he is still making special batches for people using the wrong TEA then he is being intentionally fraudulent. I have been very specific with him and he knows it.

My amount is 300ml. Exactly the same amount as I used in the 1500 series tank with a roll of FP4. I'm only developing a single sheet. The colour obviously gets darker the longer I keep developing. This last time it came out a dark straw colour as expected.

If my brew has gone off for some reason I am disinclined to try to patch it. I am a bit weary of TEA now. Although I wanted a single-part developer with great keeping qualities I am leaning away from TEA because it is too difficult to dispense and because one cannot change the pH without also changing the ratio of developing agents. A two-part developer with the developing agents in part-A and the accelerator in part-B allows a tweaking and also keeps the reactive components separated. My inclination is to now move to a glycol-based part A and either a water or glycol-based part B. It still must be a glycol base at least in part A to have the keeping qualities I believe.

The attraction of a developer with three developing ingredients was also intriguing. Something told me it may actually live up to the hype and produce great results but if the ascorbic is so fickle then I may as well be back to the Pyrocat-HD to be honest. I may make up a double-strength Pyrocat-HD instead. In the end I will not have the ability to test like an analytical chemist so I need to find a solution that works without needing the most pure form of a component or an insanely clean workspace. It could be something like an iron impurity in the pyrogallol that is reacting over a period of time with the ascorbic but how would I know ? All I know is I need to move on to something more stable.

The most important issue is obviously the reliability of a developer. One can't live with something that, for no good reason that I can see, just goes off. I don't want to be testing my developer every 5 mins.

Cheers,

Steve

 

[Photo Engineer]

SWMCL, some notes for you:

1. Even distilled water can contain iron if any of the still contains iron parts. It only takes parts per million to cause the Fenton reaction to take place.

2. I've been to the Formulary and know that Bud is an honest person after working with him for nearly 10 years now. The point here is that he is as "captive" to his suppliers as you are. If they tell him something is "A" quality, then he has to accept it as such. I have photographed carboys of chemicals with labels on that would assure you are top notch, but what if the supplier did not ship what he said? I have seen both types of TEA and I could swear that the "bad" batch was the good stuff and vice versa. The "bad" batch was crystal clear with chunks of solid TEA freezing out, while the "good" batch was dull yellow and oily.

Finally, do a strip check with leader, checking how long it takes for the BACK of the film to first darken and then turn totally black when developed in total daylight.

PE