Acid Developers

[Ian Grant]

It appears that you can use an acid developer, there's a German Patent from 1907. In think I already knew this, Amidol springs to mind.

Either you use an acid fore-bather or an acidified developer. Half a percent Sulphuric acid

German Patent no is: 29,937, now I just need to find and get translated

Ian

 

[keithwms]

Well there is urine...

http://www.cmaj.ca/cgi/content/full/172/8/1002

 

[Steve Smith]

Aren't most developers based on an acid buffered to become alkaline?

Steve.

 

[gainer]

There are developers using salts of iron, chromium or vanadium that work in acidic solution.

 

[nworth]

I found this. It's ancient. I have no idea of how or even if it works.

Acid amidol film developer (for reduced contrast)
Sodium sulfite 13 g
Potassium metabisulfite 5.2 g
Potassium bromide 500 mg
Amidol 2.6 g
WTM 1 l
Development times are long (2 to 12 hours)

 

[psvensson]

This intensifier might work as a developer too: (there was a url link here which no longer exists)

 

[Ian Grant]

I think your intensifier is a physical developer. I do have quite a lot of literature about them but most is back in the UK.

Ian

 

[Ian Grant]

I've just found a Kodak Acid "Warm tone" developer formula for Velox, based on Protosulphate of Iron - Ferrous Sulphate

Once I've converted the formulae, and put them in my database, I'll post then but it looks like over a 100 new developer formulae to add.

Ian

 

[Earl Dunbar]

I really like Amidol for paper, and have wondered about using it for sheet film. I may give it a go some day. Not sure I'd be interested in a formula that requires a long time, e.g. more than a couple of hours. I'd be concerned about the emulsion swelling and/or being more subject to physical damage.

 

[phritz phantom]

German Patent no is: 29,937, now I just need to find and get translated

Ian

post a link to it or tell me how i can find this.
if it's not too complicated and/or long, i can give you a brief translation. or i can try to.

 

[Ian Grant]

Phritz, I've not tried looking for it yet. I'm not sure how you access German Patents online, British Patents aren't as easy to access as US or the new EP patents.

Also there are Acid Amidol formulae already in my L.P. Clerc book in the UK. The Patent dev needs to be acidic to destroy a particular sensitising dye during processing, it's a Red dye and has to be destroyed before development can be complted.

Ian

 

[Thomas Bertilsson]

I tried Weston's Amidol with Fotokemika Emaks paper a while back. I probably made my best portrait prints ever with that combination, but I have abandoned amidol for the benefit of a different developer that I like better.
But I think that formula is acidic.

- Thomas

 

[Alan Johnson]

L P Clerc's Monochrome Processing revised by R.E.Jacobson section 559 explains how depth development works.G.Balagny (1903) used amidol and sulfite and added bisulfite.As this diffuses through the gelatin,because of its amphoteric character the gelatin reacts with some of the bisulfite ions reducing the acidity of the solution to allow it to develop in the depth of the layer.Development spreads slowly towards the free surface of the emulsion without reaching it.

 

[Ian Grant]

The earlier copies of Clerc are even more interesting, if Professor R.E. Jacobson was born he'd have been extremely young, I think my copy is translated then edited by Bottomley the then editor of the BJP It's too heavy to fly with

Ian

 

[gainer]

In general, ferrous sulphate in a solution with excess potassium oxalate, kept slightly acidic, was important both practically and theoretically according to Mees & James. This was compared with Pyro-sodium carbonate by Hurter & Driffield. They preferred the Pyro-Soda.

 

[Alan Johnson]

More Clerc:
The theory that the gelatin reacts with bisulfite was proved by covering the gelatin with another sheet of gelatin,when the developer diffusing through this develops the image on the surface of the emulsion,L.P. Clerc and G.E.Brown, Photography, Edition 2 1946 p244.

 

[Ian Grant]

Got the name wrong Brown not Bottomley, I'm reading too many old BJP Almanacs, I think I have a 1941 reprint of the first edition. It's a very interesting and comprehensive book, do you have D.A. Spencer's Colour Photography, which is the same publishers and a contemporary book at that time ?

Ian

 

[Alan Johnson]

No Ian I don't have Spencer's book.Maybe you can tell us what was hot in color developers in the 1940's another time!

 

[phritz phantom]

Phritz, I've not tried looking for it yet. I'm not sure how you access German Patents online, British Patents aren't as easy to access as US or the new EP patents.
Ian

i did a quick search and found this:

patent (pdf)

this is the patent i found under the number "de 29937". it contains no information about photographic chemistry, it's about a mechanism for emptying equipment for galvanization processes.

 

[Ian Grant]

No Ian I don't have Spencer's book.Maybe you can tell us what was hot in color developers in the 1940's another time!

Unlike Clerc Spencer's book has less of modern practical use, but it's a very interesting insight into older and lost processes, well written with extremely apt quotations from "Alice through the Looking Glass".

Ian

 

[Photo Engineer]

Early on in the history of photography, acidic developers (based on iron, copper or other salts) or ammonia developers which used ammonia as alkali and solvent both, were the favorites of many photographers. Even into modern times, workers researched acid developers and I remember reading many patents on exotic or not so exotic developers that used odd organics or metals or metal complexes to develop photographic materials.

AFAIK, they all fell out of favor for one reason or another, or simply vanished from the landscape except for the acidic amidol developer. It too has a major drawback in the sense that it is very unstable once mixed, but then most all amidol developers are not all that stable.

PE