Becquerel Dag, Fogged Plates

[simonechoulle]

Hi everybody,

I’ve just received new plates from a new provider. And for the very first time my plates fogged during development.
I’ve tried with old plates using the same rubylith, the same shooting and the same development and no fog.
Do you think that the silvering bath could contain some chemicals that act like accelarators (Chlorine, Bromine).
Thanks in advance for your ideas!!
Simone

[jgmotamedi]

I don’t have a good answer for you, but I would ask the plater if they use any sort of anti-tarnish coating.

[Mike Robinson]

You might ask your plater if they plated “sterling” silver rather than fine silver. If there is copper in the bath that could be a reason for foggy plates.

Mike Robinson

[simonechoulle]

Hi Motamedi and Mike
Thanks for your answers…we tried to talk to him but no way he’s very hermetic!!
We will try the plates with shorter time for developement.

Next step find another plater in Spain…
Good dags!!

Simone

[photolytic]

Thanks for your input Mike.
Assuming that copper in the bath fogs the plates why doesn’t “galvanizing” by immersion, which plates silver on the front of the plate while dissolving an electrochemical equivalent of copper from the back of the plate, have a similar effect? Perhaps you have observed some fog when you “galvanize” by immersion. Let us know if you did.

[Mike Robinson]

Hi John.
Sorry, I probably should have said, if the electro-plated silver deposit is sterling it might cause fogging. Copper in the plating bath shouldn’t cause fogging if it doesn’t get plated onto the surface.
I have not experienced fogging with immersion deposit silver galvanizing but I have done experiments on sterling silver plates and they fog. If I galvanize only half of a sterling silver plate by immersion, the galvanized side is fine, and the un-galvanized sterling side is fogged.
This was the reason I suggested that a sterling silver plating bath might be the cause. I don’t have the technical details for plating a silver/copper alloy but my guess is the external electric current must be right to deposit both metals. With immersion plating the current is generated by the silver/copper battery (clad plate) by immersion of the plate itself so only silver is plated on the silver side while copper gets dissolved into the solution.
These comments are based on my experience and observations from working with these materials. Perhaps someone who has experience in electro-chemistry could explain it better.
Mike Robinson

[simonechoulle]

Hi all,

I succeed to make images on the plate that fogged: I reduce exposure and developing time (1 stop less than usual), 30 minutes development under amberlith. I will do more tests and post them

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[simonechoulle]

Hi

Problems solved. It came from 2 lenses symmar, a 210mm and a 165mm (barrel type). We used lens hood. We’ve tested the fogged plates with a tessar and an Heliar (small lenses) and no fog.
I use the symmars for collodion and no fog problems.
Can it be a return reflection on dag…we will keep small lenses for dag.
Thanks

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