Experiences with Vitamin C developers please

[Gerald C Koch]

I buy my TEA from a company that sells soap and lotion making supplies. Their TEA is 99% pure obviously the other version would burn the skin. They ship all over the US and possibly Canada. They also sell other useful chemicals like glycols and sodium metaborate. Price are quite reasonable.

www.chemistrystore.com

 

[swmcl]

PhotoEngineer,

Does ppm mean that a great amount of the ascorbic acid in the working solution would be made ineffective as far as processing is concerned ? I'm not sure what you imply in your answer here. Take precautions ? Realise that any ascorbic acid developer is going to potentially have issues ? You've left me up in the air I'm afraid.

I am checking up on the 'clip test'. Its a pity it doesn't have a weird German name for it like the Scheimfplug (or whatever) That way the Google search would bring it up in an instant ! Not having much luck so far.

Cheers,

Steve

 

[sfaber17]

I don't have that much sympathy for the Formulary, since they know the quality of their product. The MSDS sheet they sent me has it listed as 85%. It would also be nice if they posted the MSDS sheet for it. They do post them for most of the other chemicals.
On the plus side, they responded to emails quickly and helped me find sources for some chemicals they didn't have.

 

[Gerald C Koch]

I don't have that much sympathy for the Formulary, since they know the quality of their product. The MSDS sheet they sent me has it listed as 85%. It would also be nice if they posted the MSDS sheet for it. They do post them for most of the other chemicals.
On the plus side, they responded to emails quickly and helped me find sources for some chemicals they didn't have.

Don't be too hard on PF as some developers depend on the increased alkalinity of the 85% TEA. It depends on the formula which version you use. However there are some formulas which do not make this clear.

 

[Gerald C Koch]

The Fenton reaction is catalyzed by iron and copper ions. Only a very small amount of these ions is necessary. Remember the definition of a catalyst. It is a substance that facilitates a certain reaction but is unchanged and can be recovered after the reaction. Therefore in the case of ascorbate developers a very small amount of these ions can do a great deal of damage in a very short time. From personal experience I have had an ascorbate paper developer die within 12 hours of being mixed.

The Fenton reaction is not only a problem with ascorbic acid but with other organic acids such as tartaric acid. In fact the reaction was discovered by H J H Fenton studying the oxidation of tartaric acid.

 

[sfaber17]

Good point about the DEA being more basic than pure TEA. Now I wonder what if any problem there is using the 85% TEA. Do you know examples of what developers would use pure vs 85%? What does PC-TEA call for?
I plan on doing more tests on the ascorbate loss vs time for various conditions including using some salicylic acid which I have. Note that by actual measurement, that water from my chinese stainless still did not catalyze any significant ascorbate oxidation over several hours but in city water it lost about 20%.

 

[Gerald C Koch]

Unfortunately these home-brew developers usually do not specify which version. Probably because the people who devise these formulas do not know themselves. This is why it is helpful to read the MSDS that should come with every chemical purchase. I known that there is one that uses the 85% but can't remember its name. However in the realm of commercial products Agfa's Studional used the 99% version. Something like 40% of the developer concentrate was TEA.

It's alright to use the pure TEA and just extend the recommended developing times. Of course this would take a bit of experimentation. A plus with doing this is that the concentrate would probably have better keeping properties.

I would not increase the amount of ascorbic acid that any of these formulas calls for since it is acidic and would effect the pH of the developer.

 

[swmcl]

If a very small amount of these ions can do so much trouble it makes it imperative then to use something like a salicylic acid to negate the effects I should imagine ...

It would be almost a given that any tiny amounts could come from just about anywhere. Certainly there could be impurities in other chemicals. I still think a hardy developer should compensate for these small impurities.

 

[Gerald C Koch]

It would be almost a given that any tiny amounts could come from just about anywhere. Certainly there could be impurities in other chemicals. I still think a hardy developer should compensate for these small impurities.

Commercial developers that contain ascorbic acid contain a chelating agent for this very purpose. They would not be commercially viable with one. A commonly used one is DTPA. MQ or PQ developers did not have this problem and the only chelating agent was for calcium ions in hard water.

Some years ago I played around with these glycol-TEA based developers but decided that the required formulations were too restrictive. The use of sulfite or bromide was not possible.

 

[Photo Engineer]

Almost all chemicals, as Gerry said above, have contaminants and many contain Iron salts as a contaminant. Thus, home brewed ascorbate developers are subject to catalytic decomposition. As for DEA vs TEA, I've used different TEA purities interchangeably with little harm to anything even though there is a small pH change. The other ingredients such as Sulfite tend to damp out differences, and DEA is rather harmless unless you are making a skin cream.

PE

 

[Photo Engineer]

Now for a repeat of my former long post about a developer strip test.

1. Cut the exposed leader from your film. This is about 1 - 2 inches long.
2. Pour 100 - 200 ml of developer into a small beaker or plastic cup.
3. In the light, insert the film leader into the developer BASE SIDE FACING YOU.
4. Watch and time it until the base side is BLACK.
5. The time it took should be close to, and generally longer than the recommended development time for this film.

~time passes and you have more film to process but you wonder about your developer~

1. Repeat test above.
2. If film is blank or nearly so, the developer is bad.
3. If the film takes a slightly longer time to blacken, then the developer is going but can be used with a longer development time.
4. If it is the same as before, then there is no problem.

Now, there you are, the developer activity test. Not so hard when you consider it, is it?

PE

 

[swmcl]

Photo Engineer thank you for being specific. It has been quite a search for the actual details. I'm assuming the base side is the film backing. FP4 in roll form does not have the dye on the backing that the sheet film does. I'm personally using sheet in the main although can obviously get roll film for testing.

Cheers,

 

[swmcl]

I have done another single sheet in the developer with a pinch of ascorbic in the water just before adding the 510 concentrate.

The gradient for a 7 min development time has increased to 0.361 from the initial figure of 0.316. I believe this would indicate a loss of ascorbic in the concentrate for whatever reason.

It is quite saddening that here in this thread someone who obviously has a tonne of experience says, "Commercial developers that contain ascorbic acid contain a chelating agent for this very purpose." The purpose being to offset the effects of mildly contaminated products in the developer process. Yet there are webpages surrounding the 510 Pyro (in this case) where claims are made that would ignore such advice and practice.

I thank you Gerald and Photo Engineer for your posts. Although I am disheartened having spent good money in good faith because of what seemed to be very reputable websites, a bit of serious advice and learning is what I appreciate. My desire was to try to standardize my process doing all the right tests.

It isn't the first time in this field of activity that there is so much 'black magic' flying around !

 

[swmcl]

Gerald,

Why do you say the use of sulfite or bromide was not possible ?

Do these products not dissolve into glycol ? In Pyrocat-HD I believe there is a potassium bromide and sodium metabisulfite in the Part A ...

Is the use of the these two chemicals in the Pyrocat-HD not as effective as one would hope ?

Quizzical ...

 

[Gerald C Koch]

Commercial developers that contain ascorbic acid contain a chelating agent for this very purpose. They would not be commercially viable with one. A commonly used one is DTPA. MQ or PQ developers did not have this problem and the only chelating agent was for calcium ions in hard water.

Some years ago I played around with these glycol-TEA based developers but decided that the required formulations were too restrictive. The use of sulfite or bromide was not possible.

The following sentence "They would not be commercially viable with one." in the quoted post should be "They would not be commercially viable without one." Don't know how that slipped through.

 

[Gerald C Koch]

Gerald,

Why do you say the use of sulfite or bromide was not possible ?

Do these products not dissolve into glycol ? In Pyrocat-HD I believe there is a potassium bromide and sodium metabisulfite in the Part A ...

Is the use of the these two chemicals in the Pyrocat-HD not as effective as one would hope ?

Quizzical ...

Inorganic compounds have very limited solubility in organic solvents. The rule that every chemist is taught is "Like dissolves like." Which means organic compounds dissolve in organic solvents and inorganic compounds in inorganic ones. With glycols and alcohols the presence of -OH groups does increase the solubility but usually not enough to be useful. In Pyrocat-HD since glycols are hygroscopic there is probably enough water present to provide some solubility. There are of course exceptions. Larger ions dissolve better in organic solvents.

As far as the Pyrocat-HD glycol developer the amounts of potassium bromide and sodium metabisulfite are 0.1 g/100 ml and 1 g/1000 ml. Not very much. You might run into trouble increasing these ten-fold so that their concentrations (at 1:100) approach those of most other developers.

As a practical demonstration say you have some 70% isopropyl alcohol but you need 100 %. Just add ordinary salt until no more will dissolve and the pure isopropyl alcohol will float to the surface. The alcohol is not soluble in the salt brine. This process is known as "salting out" and is used commonly in organic chemistry.

This points out an interesting fact. As the series of alcohols; methyl, ethyl, propyl, butyl, .. become less polar in nature their solubility in water decreases. Thus when we get to butyl alcohol it is not completely miscible in water like the others. In other words it is becoming less water-like and more organic.

 

[ritternathan]

Gerald,

Why do you say the use of sulfite or bromide was not possible ?

Do these products not dissolve into glycol ? In Pyrocat-HD I believe there is a potassium bromide and sodium metabisulfite in the Part A ...

Is the use of the these two chemicals in the Pyrocat-HD not as effective as one would hope ?

Quizzical ...

If you are going to mix up Pyrocat-HD in glycol, just do the -HDC version: you leave out the Pot Bromide and Sod Metabisulfite and replace w/ 4g/L of Ascorbic Acid--it's in the recipes section under Pyrocat. With the -HDC, for A just measure out the three chemicals, pour into glass bottle, fill with glycol and stir every so often, it will dissolve w/out heat in about 3 to 5 days depending on conditions.

 

[swmcl]

Gerald,

I thought Pyrocat-HD had 1g of the bromide and 10g of the metabisulphite in polypropylene glycol...

I must check again.

Cheers,

 

[Gerald C Koch]

I am not a fan of developers like 510-Pyro. Their formulations are arrived at without much attention to scientific detail. For example, do the amounts of developing agents represent the optimal ratios or would different ratios provide better results? Is the pH of the working solution optimal? Why would you add ascorbic acid to a staining developer since the ascorbic acid will inhibit stain production? And on and on. We shall never now because no one has done the drudge work of varying the parameters and doing the necessary sensitometric analyses. It's all well and good to come up with a new developer BUT you owe the users the very best effort. Unfortunately the creators of these "miracles" are not willing to follow through. I don't wish to get into a protracted argument. But these are my opinions on the subject.

I sympathize with the OP and his difficulties. When trying to standardize on a developing method it is best to stick with well defined developers. There are many to select from both commercial and "roll your own." There is the old standbys D-76 and D-23 and commercial products like HC-110 and Rodinal. And many, many more.

 

[Alan Johnson]

This is the only thread on the internet at this time that paints 510 Pyro in such a bad light.I made up some and used it to develop TMY for the time in the mdc (+15% as that time for rotary processing.)
Very sharp. nice tonality, grain consistent with pH-9+.I would increase the time I used by 20% in my case.
I repeat, there is no thread anywhere on the internet at this time except this one which considers the occurrence of the Fenton reaction during the course of development as being significant.
Thoroughly misleading, look up the various threads about the Pyrocat variations that contain vit C, no problems reported.

 

[swmcl]

Funny that ...

I just bought my first bottle of Rodinal because of this and the first negative has a gradient of 0.611 after 8 mins of slow hand rotation (1:50) with an estimated ISO of 64 on FP4 and it is super clean with low f+b of 0.12. I will go ahead in the nearish future to get the curves.

However, alongside this I have purchased a bunch of bulk chemicals so I may as well dream up a brew or two as the chemicals will only go off.

Perhaps I'll make a 44 gallon drum of Pyrocat-HD ... (only joking)

 

[sfaber17]

I was thinking along the lines of Gerald, wondering if maybe some folks in AZ who shoot under 15 stop brightness ranges are mixing up a developer and then saying how great it is and now they are not getting blown out highlights, and how fine a grain it has, when in reality the developer is running at a very low gradient and their EI is a couple stops lower than the film speed. That doesn't help when someone from the midwest is wanting a gradient of .5 since they shoot under overcast 4 or 5 stop scenes, and there is no characterization of the developer presented. I have not given up on 510 Pyro yet, nor am I convinced that Fenton is causing our low gradients, but it definitely is susceptible to Fenton problems. The author of the Pyrocat series has done the homework and presented it well though.

 

[Photo Engineer]

The results with Ascorbate developers (other than the early packages of Xtol), are scattered and varied. Many observe sudden death syndrome, but others do not. Much research has gone into this and the best answer is the Fenton reaction and the scattered nature is due to the mix of ions in the water used and methods of storage.

PE

 

[Alan Johnson]

It is known the reaction may occur in storage of film developer, the question raised here was if it can occur during the few minutes of actual film development.
No recorded instances I believe.

 

[Photo Engineer]

I agree. This reaction takes time.