Au In Developer?

[wildbillbugman]

I apologize for having attached this question to an existing thread which has nothing to do with the question. As gold in an emulsion can cause fogging, can gold be added to the developer instead of the emulsion? Will it still cause fogging? I apologize AGAIN if this question has been asked before.
Bill

 

[NedL]

Hi Bill, You probably already know you can add it to hypo to make sel d'or, a combination fix/toning step. And I've read about making "self toning" POP by adding small quantities to the POP "emulsion" and then not washing before fixing in hypo ( sounds like a recipe for staining to me, but I've never tried it... ) Just a few days ago I was wondering what would happen if I put a drop of gold chloride in with the silver nitrate for a salt print, I still might try it.

 

[wildbillbugman]

Hi NedL,
If you "wonder", by all means, try it ! Au and S in silver-halide emulsions is known to increase speed. I am wondering if the Au in a S solution(developer) will increase the "apparent" emulsion speeds.

 

[NedL]

Oh that rings a bell! I'd never be able to find the reference, it was something like "the photographic journal" from over 100 years ago, but it said something along the lines of: "Very experienced workers already know that an image can be intensified with a weak solution of gold chloride, applied such and such a way..." this was during a development step, prior to fixing or toning.... I had the impression that the effect was slight bleaching in the highlights and strong intensification. The author left it as a sort of "trade secret" and did not explain further!

Good luck, someone here probably knows!

 

[Hexavalent]

Hi Bill! Long time no see

Au added to developer will not have the same effect as Au being used during an emulsion make. In simple terms, Au is usually added during emulsion making to increase "speed" by directly altering the AgX crystal habit. Adding Au to a developer will not increase sensitivity. If you are finding that your Au treated emulsions are becoming too foggy, reduce the amount of Au, the finishing time, and watch the temperature closely (a few degrees can change the reaction speed 10-fold). Overwashing can also contribute to fogging.

PE can likely provide a more accurate explanation (and correct my errors )

 

[wildbillbugman]

Thank you Ian,
That is much what I expected. I generally use Steigmann's solution's added during precipitation. Lately, I have been up to something very different. I am keeping it close for now . No secrets. I just want to be very sure of myself before I open my mouth.

 

[Gerald C Koch]

If you attempt to put a gold salt in a developer the salt would immediately be reduced to metallic gold.

 

[Photo Engineer]

As I noted in another thread, use of gold in the developer is useless for increasing speed. In chemical sensitization it is used with sulfur (hypo) at a ratio of 1 part gold to 3 parts sulfur.

PE

 

[Mustafa Umut Sarac]

If you attempt to put a gold salt in a developer the salt would immediately be reduced to metallic gold.

And you become rich

 

[Athiril]

Think of the film as a semi-conductor and the developer as an amplifier. The gold and sulphur compounds dope the semi-conductor and alter the band gap.

 

[Photo Engineer]

That is waaaay over the top for most.