From: Jack Fulton (jefulton1@attbi.com)
Date: 02/14/03-12:26:07 PM Z
Philippe:
Terrific . . verrrry interesting. Since I work with the reversal process
on both film and paper . . perhaps, I should try a copper sulfate bleach? do
you think this'll work well?
I'd dash right out to my studio to give it a try but am leaving for central
Nevada and the chilling cold to photograph the opening of a cultural center.
Upon returning on Sunday if you might answer, I'd check . if not, I will,
then, dash to the studio.
Best . . and, thanks
Jack
> you say:
> "but, I wonder why the great stain using the permanganate bleach vs the
> dichromate."
>
> Well, the reason is that potassium permanganate, when it bleaches, meaning
> when it oxydises, or when it is getting reduced, turns into manganese dioxyde,
> a dark brown non-soluble powder that stays in the fibers etc.
>
> On the other hand, dichromate does not produce such a reduced dark molecule,
> and moreover, the reduced form of dichromate is still soluble and remains
> dissolved in water. That's why nothing stays in the paper.
>
> I personnaly would tend to use non-toxic bleaches based on other formulations.
>
>
>
> Cheers,
>
> Philippe
>
> |-----Original Message-----
> |From: Jack Fulton [mailto:jefulton1@attbi.com]
> |Sent: Friday, February 14, 2003 16:22
> |To: alt-photo-process-l@skyway.usask.ca
> |Subject: Re: Pt IV to Pt II
> |
> |
> |Richard . . . I mixed both bleaches the other day for knowing that the
> |permanganate is used in a 'cleaning' solution for photo stains I'd not
> |thought of it for my reversal work. But, in doing so and using on fiber
> |paper there was a strong stain. I further found that there are
> |two formulae
> |for the clearing baths employing the permanganate and
> |dichromate bleaches.
> |My literature says to use Potassium or Sodium Metabisulfite for the
> |permanganate bleach and just Sodium Sulfite for the
> |dichromate. Ilford's
> |formulae says only to use Sulfite for the permanganate. But,
> |there I was
> |with this horrendous stain. My chemicals books suggest the Potassium
> |Metabisulfite replaces Sodium Bisulfite weight for weight and
> |that it does
> |the same things as Sodium Sulfite . . . but, I wonder why the
> |great stain
> |using the permanganate bleach vs the dichromate.
> |Hope I've made this clear so early in the morning.
> |Jack
> |
> |
> |
> |>>> Someone, recently, posted a formula for a bleach used in
> |> reversal
> |>>> processing.
> |>>> As I remember, it was Potassium Permanganate and Sodium
> |> Bisulfate. I
> |>>> actually cannot find any reference to this bleach. I
> |> also think it was
> |>>> referred to as a modified Kodak R9 bleach. My records
> |> indicate the R9
> |>>> employs Potassium di(or bi) chromate and Sulfuric Acid.
> |>>>
> |>>> Any ideas folks?
> |>>> Thanks
> |>>> Jack
> |>>>
> |> I can't find either R-9 or modified R-9 but reversal
> |> bleaches are all about the same. Here are two.
> |> Bleach No.1
> |> Potassium bichromate 5.0 grams
> |> Sulfuric Acid 5.0 ml
> |> Waer to make 1.0 liter
> |> As always, add the acid slowly to the water. Sulfuric
> |> evolves a lot of heat when it goes into solution.
> |>
> |> Bleach No.2
> |> Potassium Permanganate 2.0 grams
> |> Sulfuric Acid 5.0 ml
> |> Water to make 1.0 liter
> |>
> |> The permanganate bleach softens the gelatin more than the
> |> bichromate bleach.
> |> Alt processes people should be well aware of the hazards
> |> of bichromate.
> |> After bleaching in either bleach the film should be
> |> cleared in:
> |>
> |> Clearing bath
> |> Sodium bisulfite 50.0 grams
> |> Water to make 1.0 liter
> |>
> |> Sodium Sulfite or Sodium metabisulfite may be used weight
> |> for weight for the bisulfite.
> |> ---
> |> Richard Knoppow
> |> Los Angeles, CA, USA
> |> dickburk@ix.netcom.com
> |>
> |>
> |
> |
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