Re: Van Dyke Reducer

KBr in that formula is probably not doing much.

Generally, if you increase bromide in a solution, the silver ion
concentration goes down. Depending on the concentrations, the silver may
be insoluble AgBr or soluble complex. But thiosulfate is a lot more
powerful ligand and takes away most silver from silver bromide or silver
bromide complex ions.

On Fri, 16 Dec 2005 16:57:14 -0600, "Michael Koch-Schulte"
<mkochsch@shaw.ca> said:
> I'll answer my own question. The formula works fine without the potassium
> bromide (so far anyway). I bumped up the potassium ferricyanide to .3 or
> .4
> g. Used the same sodium thiosulfate 5 g. Took about one to two minutes to
> "brighten" up the print. Perhaps someone could explain what the how the
> potassium bromide affects a VDB print when used as a reducing agent. Thx.
>
> ~m
>
>
> ----- Original Message -----
> From: "Michael Koch-Schulte" <mkochsch@shaw.ca>
> To: <alt-photo-process-l@sask.usask.ca>
> Sent: Friday, December 16, 2005 4:32 PM
> Subject: Van Dyke Reducer
>
>
> > Wynn White's article on VDB lists:
> >
> > Potassium Ferricyanide .25 gm (one micro spoon used for
> > stirring coffee)
> > Potassium Bromide .2 gm (10% solution 2 ml.)
> > Hypo 5 gm
> > water to make 1000 ml.
> >
> > as the formula for Van Dyke Brown reducer. I don't have Potassium Bromide
> on
> > hand. Is there something I can use as a substitute? Is there another way
> to
> > reduce a VDB?
> >
> > ~m
> >
>
Received on Fri Dec 16 17:23:19 2005