[pure-silver] Re: Pyro Was: Re: AW: Re: Any advice for purchase ofdensitometer.
- From: "Richard Knoppow" <dickburk@xxxxxxxxxxxxx>
- To: <pure-silver@xxxxxxxxxxxxx>
- Date: Sun, 26 Dec 2004 14:18:37 -0800
----- Original Message -----
From: "Georges Giralt" <georges.giralt@xxxxxxx>
To: <pure-silver@xxxxxxxxxxxxx>
Sent: Sunday, December 26, 2004 1:27 PM
Subject: [pure-silver] Re: Pyro Was: Re: AW: Re: Any advice
for purchase ofdensitometer.
> Peter De Smidt a écrit :
>> Has anyone tried Patrick Gainer's bleach and re-develop
>> in pyro? With
>> this technique you take a negative that's been processed
>> in your
>> standard non-pyro developer. YOu then bleach it with, if
>> I remember
>> correctly, a standard sepia toner style bleach. You then
>> develop the
>> negative in PMK, although I expect that the other
>> staining pyro
>> developers would work as well. You can develop in fairly
>> low level
>> light. If you make a print from your regular negative,
>> and then compare
>> it to a print made after the Gainer process, then this
>> would seem to be
>> a good (but not perfect of course) way seeing what pyro
>> does. I'll have
>> to see if I've any PMK left. It would be 7 or 8 years
>> old.
>>
>> -Peter
> Hi Peter !
> Following a processing mistake, I was left with a quite
> thin negative
> roll. (to say the less...)
> My only option was to go get intensifiers, or use the
> bleach/re devellop
> technique (I figured this myself, having no access to P.
> Gainer article,
> BTW)
> So I bleached the neg roll in a Kodak sepia toner bath,
> and dev. it in
> PMK 1+2+100 for the time it should have had if dev.
> normally in this. I
> do not recall if I re fixed the film or not.
> It worked. My un printable negative has become an awfully
> difficult
> negative to print. But I've got an image....
> Later, I was told to use the full sepia toner to add some
> more density
> to the neg. On time, I'll try it, after all I do not risk
> ruining
> negatives, they _are_ ruined...
> Enjoy ;-)
> And all my thoughts go the Asian people suffering from
> this earthquake.
> --
Supposedly the greatest effect of any intensifier is
Kodak's In-6 Quinone-Thiosulfate Intensifer. I've never used
it so can't vouch for it.
In cases of underexposure even a powerful intensifier
(or extended development) will not produce an image where
not enough light has struck the film. There is a threshhold
below which nothing is recorded.
For bleach and redevelopment intensification a low
sulfite developer should be used. A standard film developer
may have enough sulfite in it to dissolve some of the
rehalogenated silver produced by the bleach and actually
lose some density. The best redevelopers are print
developers like Dektol. The grain of the final image is not
much affected by the developer.
Pyro stain acts like an intensifier for the colors of
light it blocks but is probably no more effective in gaining
density than a non staining developer.
Re-halogenating bleaches should be used on film that is
very well washed since the bleach can combine with residual
thiosulfate to form Farmer's reducer. The re-halogenated
silver also should be well fogged before redevelopment.
Usually working in bright room light is enough.
Kodak has a number of intensifier formulae, I think the
only one they packaged was the familiar Chromium
intensifier. This uses a dichromate bleach with Hydrochloric
acid with re-development in Dektol/D-72.
Getting back to Pyro, it seems to me that Ferricyanide
bleach does not affect Pyro stain so repeating the bleaching
and redevelopment may increase the stain density.
If anyone wants the In-6 formula I will post it, its
fairly long.
---
Richard Knoppow
Los Angeles, CA, USA
dickburk@xxxxxxxxxxxxx
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