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Re: Hypo Eliminators (was: Dichromate and the plate)
At 10:45 PM 03/28/2000 -0500, you wrote:
>On Sunday, March 26 Sil Horwitz wrote:
>> Don't confuse "Hypo Eliminators" with "Wash Accellerators." Kodak now
>> specifically proscribes the HE series, noting they are harmful for
>> long-term storage of prints. Wash Accellerators are buffered and are only
>> very slightly alkaline. They are aids to washing; HE solutions actually
>> destroy hypo, and just incidentally, adversely affect gelatin. I'd keep
>> away from them, including that horrible example of "caustic soda" (sodium
>> hydroxide) which can do only harm.
>My partner Harry Kalish wonders the following: If HE-1 was used about 10
>years ago in the washing process using the old Portriga Rapid pqper, what
>problems would one expect to see with the gelatin? Would there be changes in
>the print color over time?
>Thanks for any help you can give,
>Sarah Van Keuren
Hypo eliminator was found to cause a certain amount of disruption of the
emulsion, essentially pinholes. Its of no consequence with prints but can
be a problem with film.
Prints treated with HE-1 may be more subject to attack by atmospheric
polutants than those which had just a little thiosulfate left in them. If
the prints were toned at all it will make no difference.
Until about 1961 it was thought that the ideal condition for prints and
film was to be washed completely free of thiosulfate. Large amounts of
fixer left in the emulsion does attack the iamge silver and cause fading
and staining. However, T.H.James of Kodak found that a very small residue
of thiosulfate left in the emulsion protected the silver by causing a small
amount of sulfiding. It was enough to reduce the effects of further
sulfiding and of oxidation and redox reactions due to oxides and peroxides
in the atmosphere.
This was enough to cause Kodak to revise its recommendatons for washing
of printing paper.
The hypo eliminator itself does no subsequent damage to the prints it was