From: Ed Inman (email suppressed)
Date: Mon Feb 15 2010 - 14:09:04 PST
Black & White bleach is typically an acidic solution of potassium permanganate (purple) or potassium dichromate (orange) which serves to dissolve developed silver bromide particles while leaving undeveloped particles unaltered.
As such, its function is the exact opposite of fixer.
After first development, the bleach dissolves the negative image, leaving, therefore, the remaining positive to be exposed and developed in the second development stage.
There is generally no need to use b/w fixer after the redevelopment (as there is in theory nothing left to "fix" or clear) but some people use it anyway for its emulsion hardening properties.
>From: JEFFREY PAULL <email suppressed>
>Sent: Feb 15, 2010 3:40 PM
>To: email suppressed
>Subject: 2 sorts of photographic "bleach"
>BLEACH #1: One sort of bleach converts (rehaloginates) the silver part of the image back into a compund similar to the original silver halide in the
>unexposed image. Then the fixer can remove that reconstituted silver halide.
>BLEACH #2: In developing colour films, a molocule of colour dye is also formed for each molecule of exposed silver halide turned black by the developer.
>Once the dye molocules have been determined by the silver image, you no longer want that silver image.
>This other sort of bleach then removes that silver part of the image leaving only dye, as was mentioned.
>I'm pretty sure this is correct.
>Anybody want to confirm or correct this? Please.
>(I know some of the spelling is probably wrong.)
>On Mon 15/02/10 19:36 , Cathy Rogers email suppressed sent:
>> As far as I'm aware the celer-reverser kit is b&w chemistry.
>> FROM: Ken Paul Rosenthal
>> TO: email suppressed
>> SENT: Monday, 15 February, 2010 18:09:24
>> SUBJECT: Developing Color in B/W Reversal Chemistry
>> >Has anyone had any experience of developing Plus-X 7265 (super 8 b&w
>> reversal) with the celer-reverser kit?
>> Per the original question above; please note that one cannot develop
>> b & w film in color chemistry because bleach in color processing
>> removes the silver, leaving the color dye-based image behind. If the
>> image is silver-based--as it is in b/w--then no image will be left.
>> Hotmail: Powerful Free email with security by Microsoft. Get it now.
>> info on FrameWorks, contact Pip Chodorov at .
>> For info on FrameWorks, contact Pip Chodorov at .
>For info on FrameWorks, contact Pip Chodorov at <email suppressed>.
For info on FrameWorks, contact Pip Chodorov at <email suppressed>.