[pure-silver] Re: Restoring faded prints

"Richard Knoppow" <dickburk@xxxxxxxxxxxxx>

"Nicholas O. Lindan" <nolindan@xxxxxxxxxxxxx>
> The idea that faded prints are not recoverable has always
> annoyed me.
There is a chemical method which was published in one of the Kodak books ... I will cudgel my brain 

No need to cudgel...  Google knows all.  Reproduced
below.
I confess I didn't use the method. Formaldehyde, Potassium Permanganate, and Conc. Sulfuric Acid aren't in my chemicals cupboard. 

I decided a few hours of PhotoShop would be a better idea.
The result looked good, but large liberties were taken in the restoration. At ~3 hours / restoration 
you can't do very many in PS, and it certainly isn't
cost effective.

Somewhere there must be a 50 cents/50 seconds method.
A modified scanner ...

The postings on badly washed prints fading brought
the matter to mind.

=============================================================

03:00 22 March 2000, Richard Knoppow wrote:

The image may not be recoverable. Over time the silver has been
turned into silver sulfide and silver oxide. The sulfide migrates in
the emulsion staining the highlights.
 The prints should be copied using a deep yellow filter (#11 or G) to
make copy negatives.
 Kodak published the following procedure for restoring faded prints
on _developing out_ paper. Do NOT use this on toned prints on POP, it
will destroy the image.

1. Clean the print thoroughly with film cleaner or some other
non-water-based cleaner.
2. Fix the print in a plain hypo bath. Wash the print thoroughly.
(These instructions pre-date hypo clearing agent. I think a treatment
with it would be beneficial before the washing step here).
3. If the highlights are stained treat in a solution of the folowing:
Kodak Rapid Liquid Fixer with Hardener. Dilute at film strength. To
the diluted fixing bath add:
Citric Acid,  28 grams per liter.
Treat only one print at a time and watch it closely. Stop treatment as
soon as the stain has cleared. If the solution attacks the image stop
it immediately.
 Wash the print thoroughly after treatment. Again, these instructions
pre-date KHCA and it is likely beneficial here.
4. Bleach and redevelop the print as follows:
A. Treat with Kodak Special Hardener SH-1. This is a Formaldehyde
hardener. Formaldehyde is toxic and a carcinogen. Its possible the
process will work without it but the bleach is very swelling and may
damage the emulsion without the extreme hardening of this solution.
 Treat in the hardener for five minutes and wash the print.
B. Bleach in Kodak S-6 Stain Remover. and wash. Do NOT use KHCA after
the bleach, the sulfite will partially dissolve the halide.
C. Expose the bleached print to strong light.
D. Redevelop in Kodak Dektol 1:2 or similar low sulfite active
developer.
D.Wash thoroughly.

A plain hypo bath is:
Sodium Thiosulfate, crystaline                  240.0 grams
Water                                             1.0 liter

If anhydrous thiosulfate is used the amount is 160 grams/liter
Crystaline thiosulfate is very endothermic so needs to mixed in hot
water (125F). Anhydrous thiosulfate should be mixed in water not over
90F.

Kodak Special Hardener SH-1

Water                                           500.0 ml
Formaldehyde, about 37% solution by weight       10.0 ml
Sodium Carbonate, monohydrated                    6.0 grams
Water to make                                     1.0 liter

Note cautions above re. Formaldehyde

Kodak Stain Remover S-6
Stock Solution A
Potassium  Permanganate                         5.0 grams
Water to make                                   1.0 liter

Stock Solution B
Cold water                                    500.0 ml
Sodium Chloride (don't use table salt)         75.0 grams
Sulfuric Acid , concentrated                   16.0 ml
Water to make                                   1.0 liter

(Note: Most table salt contains iodine and other impurities, the
iodine can cause staining)

For Use, Take equal parts of A and B. The solutions do not keep in
combination, mix it just before use.
Bleaching should be complete in 3 or 4 minutes at 68F.
 The brown maganese dioxide stain formed by the bleach can be removed
by treating in a 1% Sodium Bi-sulfite solution. Wash prints after
bleaching.
The print should be exposed to strong light, preferably daylight,
before redeveloping.'
Re-develop in Kodak D-72 or Dektol diluted 1:2. 
==
Nicholas O. Lindan
Cleveland Engineering Design, LLC
Cleveland, Ohio 44121


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