Edwal Super 20..Chemistry Question

[eclarke]

A formula was posted here for Edwal Super 20. I'm going to make it as specified but have a question for the real chemists here. The formula calls for .2154 ml of pure sulfuric acid.. What can this tiny amount do in this developer?

 

[Gerald C Koch]

The sulfuric acid adjusts the pH because the formula calls for the free bases paraminophenol and paraphenylene diamine. It is best added as a 10% solution because of the small amount required would be hard to measure.

However developers like this one are not needed with today's fine grain emulsions and the developer may actually cause dichroic fog with some. There was a reason why these developers fell out of favor.

Paraphenylene diamine is poisonous and also causes severe allergic dermatitis. It is a cross sensitizer and may cause an allergy to develop toward other developing agents like Metol and the color developing agents. Use a dust mask and goggles when handling the solid and also nitrile gloves with the powder or its solutions. Paraphenylene diamine is a suspected carcinogen and mutagenic. Best to leave it alone. Developers like Xtol or Perceptol will produce grain almost as find as Super 20.

 

[eclarke]

Thanks, Gerald.
I use around 2# of ppd a year and keep 10% solutions of all my acids, which I weigh for small quantities. Thanks for the cautions. I should have posted the info for the formula, it's interesting that it calls for the tiny amount of sulfuric acid, is specific about final pH and says to bomb it with hydroxide or acetic acid at the end to adjust the pH. I'm enclosing the recipe for you. Thanks for the feedback..Evan Clarke

Hi Everybody,

First a little background with a post I put up on Photo Net in 2003. It was as follows:

Through the mid 60s to the 80s I used Edwal Super 20 exclusivly after trying virtually every developer then available, becase it gave an unequaled combination of very fine grain, high sharpness and (most of all) super compensation for the usually over-contrasty outdoor shots taken in the harsh Florida sun. I had originally become a fan of it because I had supplemented my TA stipend in graduate school by doing affordable 35mm portraiture and found it gave beautiful grain and tonality in that application.
I am ready to do whatever it takes to duplicate the formula. Bud, the owner of the Photographers Formulary has talked to Bill Troop, co-author of the Film Developing Cookbook about the formula given there on page 67 and Mr. Troop has said that it is NOT, in fact, the correct one. The Film Developing Cookbook mentions in a note regarding the formula given that "incorrect" formulas have been published elsewhere. The Photographers Formulary suggested that if I could obtain one or more of these it (in conjunction with the Troop formula) it would give me a starting point to experiment with to try to home in on a working formula.
If Super 20 can be duplicated , Bud would consider making it available to the B&W enthusiast community. I don't know how many of you have used Super 20 in the past, but rediscovering the formula would be a great service to the B&W community. It is a staining developer with many Pyro-like qualities, but with much finer grain, better acutance and much better compensating characteristics. If you can give me any leads I will be dilligent in following up and getting you the results of my attempts to replicate the formula. I have thousands of Super 20 negatives so I know exactly what results I am looking for! Thanks! Jay Ludvigh

There was a good bit of discussion and speculation at that time, but nothing definitive regarding the exact formula. After conversations with Bill Troop and a bit of detective work I was able to track down Bob Schrader who was the production line supervisor for Edwal during the last years Super 20 was in production. He agreed to give me the formula, but asked that I not disclose it because he thought he might someday want to market it. I mixed it up using the facilities of the chemistry lab at the university where I'm adjunct faculty, because it is hard to get into solution an requires a heated magnetic stirer to get the job done. I compared it to my original negatives and while there were some differences because of the changes in more modern films it was clearly the same developer. I also was able to get an unopened, well stored bottle of Super 20 and compared it to my brewed version with modern films and found the results identical. So, what we have here is the real thing.

The problem is that it is a pain to brew and I no longer have access to the chem lab due to a change in personel. I have been thinking that with the actual formula and expert input from savy APUG members, a more user friendly home brew method could be found. I have tried to contact Bob Schrader but have been unable to do so and since it has been over 9 years since he asked me to keep the formula to myself and nothing has happened in terms of him producing it I decided to make this post.

Here is the exact formula which he provided me. According to the chemist who helped me make the first batch it has "archaic" chemical terms and units of measure, but here it is:

To make 1 ltr

1) Hot water 120-130F (distilled preferred) approx 28 oz.
2) ParaAmino Phenol 2.62 gm
3) Sulfuric Acid 66 degree baume (pure lab grade) .2154ml
4) Sodium Sulfite 89.95gm
5)Para Phenylene Diamine 9.59gm
6) Glycin 4.797gm
7) Water to 1ltr

Desired ph-7.6
Adjust with caustic soda (sodium hydroxide)/28% acetic acid
do not add second chemical until first is dissolved

The above is the word for word info he sent me on how to make Super 20. I sent him a heartfelt e mail of thanks and have not heard from him since. I deeply hope he is not still out there planning to go into production himself and am only posting this now to benifit other "film dinosaurs" like myself.

If anyone with photochemistry expertiese out there can use the formula to figure out what Gradol was or how to brew Super 20 without having to use the sulfuric acid and ph adjustment process this could become a developer that a lot of people could use.

Jay Ludvigh

 

[eclarke]

Evan - just be careful what you read about working characteristics. It's a highly solvent extra fine grain developer. High sharpness and compensation would be pretty much impossible. Also at this pH it is essentially a Glycin-PPD developer so there is likely some film speed penalty. All things considered, an odd choice for ULF

Perhaps Gerald knows, but I wonder if p-Aminophenol is superadditive/regenerative with either Glycin or PPD. If not, it would be inactive at this pH.

It's interesting that other than the substitution of 2.6g p-Aminophenol for 6g Metol (a significant change), the rest of the formula is virtually identical to Edwal 12 with some acid to lower the pH.

I'm a little obsessive and I make two sheets of everything I do. I use Germain's Finegrain as my go to developer and prefer it to Edwal 12. I have a huge supply of spare exposed sheets to use for developer play like this (read as hundreds) and you never know when the magic bullet will appear! I like solvent developers even for my biggest formats..I'm not a fan of edge effects and jangly sharpness. I do 11x14 because it can resolve tonal qualities better than small formats and I prefer the smooth result of solvent developers. I'm also using soft focus brassies on 11x14!!! Thanks for the input..Evan

 

[Gerald C Koch]

Super-additivity falls out very nicely from the Kendall-Peltz rule. For supur-additivity to occur one developing agent must contain an amine group and the other two hydroxyl groups. Thus we have the classic MQ developer. For Super 20 there is no super-additivity for any of the developing agents. Paraphenylene diamine is a very slow acting developing agent which is used primarily for its silver halide solvency properties. I cannot see any use for paraphenylene diamine with modern emulsions.

 

[Gerald C Koch]

A staining developer has to necessary characteristics. First it must have a very low sulfite (preservative) level. Second it must contain either pyrogallol or catechol. Super 20 does not meet either of these two requirements let alone both of them. It certainly is NOT a staining developer as judged from the formula.

BTW, hydroquinone may be made to stain under very specific conditions but is not usually used for that purpose.

 

[Gerald C Koch]

At the time that Super 20 was formulated the developing process was not very well understood. It's not surprising that combination of ingredients is not effective. Look at Champlin's odd mixtures.

As far as pH is concerned Metol is used in the very low pH D-25 (pH ~7). As to the relative activity of Metol and paraminolphenol at low pH I would have to research this.

I personally wish that "The Film Developing Cookbook" had never been published. It seems to legitimize a lot of very dubious, obsolete formulas that are best forgotten. The book ignores the fact that today's films are very different from those in use when these older formulas were concocted. And then as I have said over and over again "There is no Holy Grail" of developers. The search for this fiction only distracts people from the object of photography which is to take pictures.

 

[eclarke]

Agreed that there's no holy grail, but it's nice to be able to discuss things like developers when Ihave had hands on experience with it and not merely parrot something so,ebody else wrote. I like to tinker so I can rule things out and be able to give real info about my results. As an example, I use a nice Gitzo carbon tripod with an Arca Cube and it's a spectacular setup yet I get flamed by people about using an expensive combination. The flamers have mostly never even seen it, let alone used it. The same thing happens with developer talk. I get flamed for the Germain because everybody says he was sort of a quack and I should use Edwal 12..but...I've developed several thousand sheets in Germain's Finegrain and it's still my favorite for all films..Thanks for the input, I'm just going to dispense with the sulfuric and adjust the pH at the end. Won't be the first liter of developer I have thrown away or I might like it!! EC

 

[Gerald C Koch]

Gradol was paraminophenol hemisulfate. A curious choice since its keeping property in solution a less than for Metol.

 

[eclarke]

"Gradol was paraminophenol hemisulfate" There's the answer, and maybe what the sulfuric acid is about. I think this might be a dead end.. Thanks..Evan

 

[Relayer]

PAP base isn't soluble in water at neutral or low alkali pH. I think that Sulfuric Acid in Edwal-20 formula allow PAP base dissolved in water at acidic pH

 

[Rudeofus]

I remember I read about some biology book where the average length of some kind of bird was specified as 30.48cm. In the same way I would guess that nobody measured the volume of Sulfuric Acid to four digits (and I'm not entirely sure how exactly one would do this anyway), but that instead some simple number was converted to a different system of measurements. Looking at the other rather odd amounts in the recipe would also suggest this theory.

 

[Ian Grant]

The keeping properties of a developing agent can be greatly incresed by the addition of another. It might sound surprising but Ilford sold D&P tank developers with Metol, Hydroquinone and Pyrogallol, designed for high volumes and replenished. The Pyrogallol acts as an oxygen scavenger.

PPD also forms a complex with some developing agents, the most common being Meritol which is a PPD/Pyrocatechin complex. It may well be less toxic as a complex although the commercial developers I used which cointained Meritol did have a warning label even in the late 1960s.

Womens (and the odd vain mans) hair dyes use(d) PPD derivaties, most have changed to safer compounds but not everywhere.

Some of these developers gave exceptionally good results and in a way they were the magic bullets when they were first introduced. Modern films are less affected in terms of fine grain by choice of developer, old style films though could give grain like golf balls with the wrong type of developer and excellent fine grain in one of these off beat fine grain developers, far better than most fine grain developer from Kodak, Ilford Agfa etc.

As to why p-aminophenol in a low pH developer well Ilford used it alongside Metol in their early super fine grain developer sold in the 1930's.

Ian

 

[eclarke]

Thanks, Ian..

 

[Gerald C Koch]

PPD also forms a complex with some developing agents, the most common being Meritol which is a PPD/Pyrocatechin complex. It may well be less toxic as a complex although the commercial developers I used which cointained Meritol did have a warning label even in the late 1960s.

Another compound is between ppd and hydroquinone. This is a 1:1 addition compound where one ppd molecule sits on a hydroquinone molecule something like the two slices of bread in a sandwich. These compounds are held together by hydrogen bonds. While they are stable in solid form they dissociate back to ppd and hydroquinone or catechol when dissolved in water.

 

[Gerald C Koch]

Kodak D-25 developer was developed as a safer substitute for ppd developers. It is D-23 with the addition of 15.0 g/l of sodium bisulfite. It is said to produce fine grain comparable to that of the phenylenediamine developers with less chance of causing allergic dermatitis.

 

[Gerald C Koch]

I remember I read about some biology book where the average length of some kind of bird was specified as 30.48cm. In the same way I would guess that nobody measured the volume of Sulfuric Acid to four digits (and I'm not entirely sure how exactly one would do this anyway), but that instead some simple number was converted to a different system of measurements. Looking at the other rather odd amounts in the recipe would also suggest this theory.

There was a contributor to the BJ by the name Cyril Peckham. His formulas were rather curious in that he mixed metric units with English units (grains, scruples, etc) in the same formula. He would use whatever measure gave him a round number. His Amidol paper developer was said to be quite good.

 

[Ian Grant]

Kodak D-25 developer was developed as a safer substitute for ppd developers. It is D-23 with the addition of 15.0 g/l of sodium bisulfite. It is said to produce fine grain comparable to that of the phenylenediamine developers with less chance of causing allergic dermatitis.

D-23 and D-25 were published at the same time, in fact Kodatol was Kodak's alternative to PDD super fine grain developers, they were all part of the same research project which included an early version of Microdol. Kodak chose to sell Kodatol DK-20 and then switched to Microdol and finally Microdol-X. There were issues with dichroic fog with Kodak films and D-25 and DK-20 and later Microdol. This got worse when Kodak improved their films in the 60's.

Ian

 

[eclarke]

There was a contributor to the BJ by the name Cyril Peckham. His formulas were rather curious in that he mixed metric units with English units (grains, scruples, etc) in the same formula. He would use whatever measure gave him a round number. His Amidol paper developer was said to be quite good.

Thanks, Gerald, I'll have to check him out, I have a collection of the BJ..

 

[Relayer]

from patent US3917695:

The solubility of p-aminophenol in water can be increased by addition of inorganic acids such as sulfuric or hydrochloric

from other patents related to PAP purification you can find information about participation PAP from acidic solution. many patent state that participate PAP doing at pH > 6

 

[dynachrome]

Are you using 11X14 film or something smaller and then enlarging to 11X14? If you are using 11X14 film and grain is a worry you must be making very large prints. If you are using a small format like 35mm then just go up to 6X7 and you can make grainless 11X14s with any number of develoopers.

 

[eclarke]

Are you using 11X14 film or something smaller and then enlarging to 11X14? If you are using 11X14 film and grain is a worry you must be making very large prints. If you are using a small format like 35mm then just go up to 6X7 and you can make grainless 11X14s with any number of develoopers.

Not worried about grain, just interested in photochemistry. I photograph with formats up to 11x14 and have all the methods in place for my serious photography. I like to dabble with developers for fun and sometimes while dabbling, I bring a new tool into my arsenal. I'll make this and when it comes up in conversation, I'll know all about it!! My original question was about the tiny amount of sulfuric acid at the exact place its added to the mix, a little odd compared to most recipes..Thanks, Evan Clarke