repairing negative with dichroic fog?

I have several Plus-X negatives that have a mottled base fog with
transmitted light and a metallic sheen with reflected. I think this is
dichroic fog; it took me around six months to identify this problem, so the
negatives have been sitting in their negative sheets for quite some time.
I've tried refixing in TF-4 for about 10 minutes, but this seems to do
nothing. Is there anything else I can do? I like the images, but the prints
look fairly awful because of the fog problem.

Thanks in advance!

Often refixing the film in fresh Kodak Rapid Fixer will remove dichroic fog.
The fresh fixer has a slight bleaching property which will remove the small
amount of silver on the surface of the film. Normal fix times of 3-5 minutes
shouod be enough. Good luck.
Bernie

In article ,
s (Jazztptman) wrote:

Often refixing the film in fresh Kodak Rapid Fixer will remove dichroic fog.
The fresh fixer has a slight bleaching property which will remove the small
amount of silver on the surface of the film. Normal fix times of 3-5 minutes
shouod be enough. Good luck.

He said in his post that he refixed the negatives.

But using TF-4, which is an alkaline fixer. Would that make a difference?

"jjs" wrote in message
...
In article ,
s (Jazztptman) wrote:

Often refixing the film in fresh Kodak Rapid Fixer will remove dichroic
fog.
The fresh fixer has a slight bleaching property which will remove the
small
amount of silver on the surface of the film. Normal fix times of 3-5
minutes
shouod be enough. Good luck.

He said in his post that he refixed the negatives.

He said in his post that he refixed the negatives.

Yes, but with home mixed alkaline formula fixer. You need the activity of the
ammonium hypo in a fresh unused fixeer to provide the sllight bleaching effect
which removes the dichroic fog, if this is dichroic fog.

Usually dichroic fog is even, not mottled, but I have seen many stange things
happen in the darkroom and generally try to test for the obvious first.


Bernie

In article ,
s (Jazztptman) wrote:

He said in his post that he refixed the negatives.

Yes, but with home mixed alkaline formula fixer. You need the activity of the
ammonium hypo in a fresh unused fixeer to provide the sllight bleaching effect
which removes the dichroic fog, if this is dichroic fog.

I stand corrected. Good information. Thank you, Bernie.

"KM" wrote in message
...
I have several Plus-X negatives that have a mottled base
fog with
transmitted light and a metallic sheen with reflected. I
think this is
dichroic fog; it took me around six months to identify
this problem, so the
negatives have been sitting in their negative sheets for
quite some time.
I've tried refixing in TF-4 for about 10 minutes, but this
seems to do
nothing. Is there anything else I can do? I like the
images, but the prints
look fairly awful because of the fog problem.

Thanks in advance!


A mild siver solvent can be made from fresh rapid fixer at
film strength with 15 grams/liter of Citric Acid added. The
film should be treated in this solution and inspected
continuously. You can re-treat it if there is still some
dichroic fog left but too long a treatment will begin to
dissolve the image silver.


--
---
Richard Knoppow
Los Angeles, CA, USA

"jjs" wrote in message
...
In article ,
s (Jazztptman) wrote:

He said in his post that he refixed the negatives.

Yes, but with home mixed alkaline formula fixer. You
need the activity of the
ammonium hypo in a fresh unused fixeer to provide the
sllight bleaching effect
which removes the dichroic fog, if this is dichroic fog.

I stand corrected. Good information. Thank you, Bernie.

Alkaline or neutral fixer will not work, it must be
acidified. A good bleach is made from fresh film strength
acid rapid fixer with Citric Acid added to 15 grams/liter of
working strength fixer.
This will remove dichroic fog with little, if any, effect
on the image.
The old standard method was to use about a 1% solution of
Potassium Cyanide, which is a very effective silver solvent.
Cyanides are probably not good things to have around your
house so the modified fixer remains the best choice.


--
---
Richard Knoppow
Los Angeles, CA, USA

Richard Knoppow wrote (in part):
The old standard method was to use about a 1% solution of Potassium
Cyanide, which is a very effective silver solvent. Cyanides are
probably not good things to have around your house so the modified
fixer remains the best choice.

What's the matter, Richard? No sense of adventure?

Was there not some iodine in that, too?

--
.~. Jean-David Beyer Registered Linux User 85642.
/V\ Registered Machine 241939.
/( )\ Shrewsbury, New Jersey http://counter.li.org
^^-^^ 08:40:00 up 6 days, 10:50, 2 users, load average: 4.24, 4.19, 4.12

Jean-David Beyer wrote in message ...
Richard Knoppow wrote (in part):
The old standard method was to use about a 1% solution of Potassium
Cyanide, which is a very effective silver solvent. Cyanides are
probably not good things to have around your house so the modified
fixer remains the best choice.

What's the matter, Richard? No sense of adventure?

Was there not some iodine in that, too?

Not for clearing dichroic fog. Iodine is used in a reducer for
clearing lots of silver. It converts the silver to silver iodide.
Because silver iodide is resistant to sodium thiosulfate fixer a mild
solution of cyanide is used to remove it. A more modern version uses
ammonium thiosulfate fixer, which has an easier time with silver
iodide.
Dichroic fog is composed of colloidal silver deposited on the
surfaces of the film. Cyanide is a good enough solvent for metallic
silver to remove it. However, Ammonium thiosulfate fixer acidified
with Citric Acid is effective enough, easier to control, and much
safer than cyanide.

Richard Knoppow
Los Angeles, CA, USA