I've been digging into the chemistry of the process.
Originally Posted by mario Ag+
I've not found anything of which I'm sure Mr. Rudman is
not already well acquainted. As I previously mentioned, the
silver is oxidized by the ferricyanide. Silver + ferricyanide =
The ferrocyanide is insoluble so image integrity should
be maintained through a P. F. treatment. Assuming your
intention is to sepia tone, a P. F. minus bromide treatment
may suffice. That is no bromide during or after treatment.
Due to the extreme insolubility of silver sulfide it stands
to reason that the silver will convert.
At a minimum an interesting experiment would be a post
rather than a during bromide treatment.
You asked " is Pot Bromide essential ... ?" If so, I'd add
when is it essential, during, after, either? Dan
I'm not sure I quite understand your question Dan.
Originally Posted by dancqu
Do you mean bleaching with plain Pot. Ferri (no bromide), then sepia toning, then adding bromide after toning? Why would you want to do this? Perhaps I missed the point?
Some of the "other metal" toners work without halides - like the blue iron toner.
Adding halide after toning will probably have no effect at all. I say "probably" because I haven't tried it, although a strong salt (sodium chloride) solution is used as a clearing bath with the Colorvir toning kit (iron, zink and titanium toners).
-- Ole Tjugen, Luddite Elitist
Originally Posted by mario Ag+
This thread has horrified me.
If I was to answer Marios question above, I would have said; 'Yes, of course it is Mario'
Now reading through this thread, all the past prints that I have made are likely to self disruct over time. Could some one please tell me this is not going to happen.
I print on Ilford Mg4 FB and wash and fix as per normal.
The print is washed for 1 hr.
The print is then slid in to a tray of 1ltr of water and 10ml of Ferri-stock(10gms ferri/100ml water, as per Les McLeans book)
The tray and print is agitated sporadically throughout its 10 mins soak.
The print is washed for 2 mins
The print then enters a tray of sepia(tetenal non vario) for 10 mins
The print is washed for 5 mins
The print then enters a tray of selenium of either 1-9 or 1-4 for the desired effect.
The print is washed for a further 30-45 mins
The print then enters atray of 2x Alcha-Seltzer/1ltr R.O water for 1 min before the usual drying procedure.
This is a routine that I have been using for some time now and I have not noticed any degradation of the final print over time. They all look as crisp as the day they were printed.
Should I be adding some fix to my tray of weak ferri, and if so, how much?
I thank you in early anticipation, and also appologise to Mario for asking a question on his thread.
I've not been trying to make a point. I've got some
Originally Posted by tim rudman
potassium ferricyanide on my list of to-buy chemicals
when next I order from P. Formulary. I've taken the
OP's question as an opportunity to investigate
At least at first glance it would seem that bromide
is not needed if a sulfide toner is to follow the bleach.
Ole mentions "other metal" toners which work with
out any halide.
With the usual lights-on way of P. F. processing the
re-exposure I mentioned is included. We know that the
halides of silver are light sensitive. Now, what if the P. F.
processing is done under, say, a red safelight? What then
if the re-halogenated print is again put through a usual print
developer? My guess, the print would not reappear. Would
not because of it's P. F. processing under a red safelight.
Besides silver ferrocyanide and the halides when
present, I dare say several other compounds of silver
could be generated with the appropriate chemical; that
during or after a P. F. treatment. That you've mentioned
at least with the halides or a mix thereof.
But for some of those "Cool" moves that might be made
re-exposure is necessary. So, the light sensitivity of what
ever compound of silver results must be considered. The
halides are sensitive and some what the soluble nitrate.
Others I couldn't say. Dan
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Not unless you want to lose the image. Fix + ferri = Farmer's Reducer. The image will not resurrect.
Originally Posted by Stoo Batchelor
Bromide is not the only halide. Non-iodized table salt will do. Canning salt is such. You get a silver chloride image which responds to sulfide for toning or which may be redeveloped in a staining developer for other purposes. Light is necessary for the latter. Sulfide will turn unexposed film or paper brown.
Originally Posted by gainer
Thanks for the reply.
Sorry to dig deeper, and if i sound a bit dense here, but i want to get this straight. From what you are saying, I assume that all is o.k with my toning routine? As I am only slightly bleaching out the highlights with the ferri, as soon as I enter the print in to the sepia toner, any un-developed silver is re-developed, providing that I use a sulphide toner.
Just one other question, if I may?; Would a Sepia toner made out of Thiourea do the same job as the sulphide based sepia toner, i.e; re-develop any un-developed silver?
Perhaps I can add my comments here too Stoo.
Originally Posted by Stoo Batchelor
'Gainer' is right about fixer + ferri = Farmer's reducer, which is non reversible. This is also important as you must take care to properly remove fixer from the paper too, before putting it into your ferri/halide bleach.
"As I am only slightly bleaching out the highlights with the ferri, as soon as I enter the print in to the sepia toner, any un-developed silver is re-developed, providing that I use a sulphide toner"
Correct - provided that you tone to completion.
"Would a Sepia toner made out of Thiourea do the same job as the sulphide based sepia toner, i.e; re-develop any un-developed silver?"
Yes, this is correct. Plus you have the advatages of no bad smell and you can pick from a range of colours from thiourea, by altering the hydroxide amount that is added to it. In kits this usually comes as a 3rd bottle of 'additive'.
There are other ways you can alter the outcome too by adding a different halide (eg kosher salt) to the bleach, by adding a little B&W developer, by putting in toner before bleaching etc etc.
Re halides - you can use bromide or chloride as previously stated, or a mix. Iodide is also usable but much trickier. If interested, there is a write up on this in my toning book under FSA toner (too long to retype here!)
Phew, I can rest at night now!
Thanks for taking the time out to answer my Question. I have actually ordered the raw chemicals now to make my own Thiourea based toner, so look forward to playing games and experimenting with some old prints.
I am the owner of a copy of your toning book, its the bible of toning. I have ballsed up many a fine print while reading it! I will read with interest the pages you have suggested.
Thanks again, glad your there.
so, i finally found out that "hypo" does not mean "hypo clearing agent", but "sodium thiosulfate".
i was wondering for a long time, why some people mix bleach with fixer and others with hypo. thanks a lot for clearing that up.
all the fixers i use don't contain "sodium thiosulfate". they contain "ammonium thiosulfate". is there a difference between those two chemicals when mixing it with potassium ferricyanide? or can i keep using the amm. thios. fixers?