Re: Reversal

["Paul A. Lehman" <palehman@xxxxxxxxxxxxx>]

I don't know if this is of any help or not, but may be
useful.

I just did a quick comparison of the various methods
that have been mentioned. Not surprising, they are
mostly very similar (except for the Ilford method, and
the Gasson method). It is clear to me that the 1st
developer is the most critical step and changing the
additives within the ranges shown will effect results
(contrast and grain) depending on the film used. 

To summarize (all values per liter final volume):

1st developer is D-76 with the following range of
additives:
     2-16g  Sodium thiocyanate
     52-60g Sodium carbonate
     3-4g   Potassium bromide
(I have a book somewhere that describes what each one
of these
  additives are doing to the silver, I'll try to find
it this week).

Bleach variations:
     10-15 mL Sulfuric acid
      9-12g Potassium dichromate
(actual values here are probably not critical, but will
effect 
  duration needed for bleaching and life span in # of
rolls)

Clear variations:
     40-100g Sodium sulfite
(actual values here are also not critical, but will
effect
  useful life span in # of rolls.)


2nd developer is Dektol
     (+2-4g Sodium sulfide for sepia tones).

The Ilford process uses their own proprietary
developers.
The Gasson process uses a modified D-19 as the 1st
developer.

A couple mention that an alternative bleach can be made
with Potassium permanganate, and an alternative
clearing solution of Potassium or Sodium metabisulfite.

Paul A. Lehman

Paul A. Lehman