Radioactive Emulsion Memory Reset, Refreshing, Fog Removal

[Mustafa Umut Sarac]

I am reading about radioactive emulsions which used at high energy physics and found memory reset or called emulsion refreshing to remove the fog.
I am not expert but this would be removal of cosmic radiation exposure during japan to italy travel or may be - I am not sure - to use the plate again and again.

That is done to keep the plate in %95 humidity , 25 celcius for few days and than dry in same chamber at %60 humidity

How can we use that technology ? At least IMHO owner of the old films or papers could use to remove fog from film or paper.


Mustafa Umut Sarac
Istanbul

 

[michr]

Scant information about how this technique works. I found this though, which you might find interesting.

http://www.lhep.unibe.ch/img/lectureslides/73_2010-5-4_Particle_Detectors_10_Emulsions.ppt

Look at the emulsion cloud detector, I wonder what the cost of using that much nuclear emulsion film must be.

Has anyone here has left their film in the trunk of the car for a few days in the summer in a high-humidity climate? When you developed the film were you surprised at how fog-free it was?

 

[Mustafa Umut Sarac]

Toro mine is after production at japan , real thing done after 1 month travel to Italy and cosmic exposure , they remove fog as much as 400 lines per square centimeters. I dont have slightest idea that and film paper fog is related or too far from each other subjects.

I think PE can cover that but he retires from forum I guess.

 

[Mustafa Umut Sarac]

May be its just the time to pm PE and poke him I researched the subject and one or two paper are on google , let me search libgen scientific articles database and turn here with more papers.

 

[removed account4]

I was under the impression that high temperatures and humidity lead to film fog. What is the memory refresh really doing? Is it just burying the incidental cosmic ray tracks in fog before the films is exposed to the particles deliberately?

mr bill in a different thread spoke about how a company he worked for would purposely test film in excessive heat ( hot boxes ) for long periods of time to see how the heat affected the film ... and it didnt.
it was color negative film.

poke around this thread
(there was a url link here which no longer exists)
foe posts by mr bill

 

[Mustafa Umut Sarac]

John , may be high humidity AND heat soften the gelatin and realign the structure. I dont have access to libgen database now - it off few hours a day - but I think arxiv is a place to look. I am going there now

 

[Mustafa Umut Sarac]

In the refreshing room there are two refresh chambers. Each chamber (Fig. 4) ∼ 1 m×1 m×2 m,
contains 760 trays. Each tray contains 9 films. In total 6840 films are processed at the same
time. The component in front of the chamber is a two-fan humidifier which provides humidity
through wet paper filters. Demineralized water is used. The ducts have tapered structures to provide
uniform ventilation inside the chamber. The air flow can be in open circuit (air from outside,
evacuated outside) or in closed circuit (air circulation without exchange).
Figure 4. A schematic drawing of the refresh chamber.
The air in the refreshing room is kept at 26-27◦C and 40% RH. A refreshing cycle takes one
week. The sequence is the following: open circuit mode at ≥85% RH for one day, close circuit
mode at ≃98% RH for three days, slow-dry mode from 98% to 60% RH for one day, complete-dry
mode down to 40% RH for one day (open circuit).

 

[michr]

Here's some more info

http://www.slac.stanford.edu/cgi-wrap/getdoc/slac-pub-11858.pdf


"Refreshing is a technology to erase tracks in emulsion film by means of forced fading. Fading occurs in any type of photographic film with the passage of time. It is caused by destruction of latent image center in a silver bromide crystal by oxidation. It is known that, by adding 5-methylbenzotriazole to emulsion, forced fading (i.e., to accelerate fading) can be realized under high temperature and high humidity environment [10]."

 

[Mustafa Umut Sarac]

K. Kuwabara and S. Nishiyama, Journal of the society of photographic science
and technology of Japan 67, 521 (2004);
T. Nakamura et al., submitted to Nucl. Instrum. Methods A

Opera film has this feature of forced fading. This implies
that, adjusting the amount of forced fading of track images in the film by controlling
temperature and humidity, the saturation of grain density by passage
of ions can be resolved.
In this paper we report the results of our study for applying the refreshing
technique to Opera films in order to extend its dynamic rage of the response
for energy loss by ionization.


As described in the introduction, refreshing makes the sensitivity of emulsion
lower and provides a possibility to avoid the saturation of response to highly
charged particles. According to the report [10], the refreshing of Opera film
for three days under the environment of 30oC and relative humidity of 98%
resulted in more than 70% of decrease in the grain density of tracks created
by minimum ionizing particles. It was also reported that an increase of fog
in the film was not observed by this refreshing. Here fog is due to accidental
grains randomly distributed in the film and it causes a problem during the
track recognition if its density is too high.

 

[michr]

It would seem the fogging of old film has other causes, cosmic radiation being one. Are the instructions to give an additional stop or two exposure when shooting on old films solely because of the base fog, or is the sensitivity reduced as well?

What would be the benefit of this process over using reducer or bleach? I'm interested in trying this technique on a negative that's too dense to print.

 

[Mustafa Umut Sarac]

I agree , ı dont know the answer. ı am attaching the only paper on that subject. May be someone read and creates a new idea.

Find attached pdf.

 

[winterclock]

The refresh process only works on undeveloped film, the high temperature and humidity accelerate the action of the methylbenzotriazole in oxidizing exposed grains. This is certainly of interest to those of us who use long expired film, but will not take the place of reducers and bleach for processed negatives. I seem to recall reading an old issue of camera mgazine where this approach was recommended for rescuing exposed, but unprocessed film for reuse. In the article last cited by Mustafa there was only slight degredation in the sensitivity of the film after refreshing.

 

[Mustafa Umut Sarac]

Winterclock and all,

Practical thinking,

For example,

- We have 40 years old Panatomic film bought from Ebay,
- and We have 30 years old Agfa Brovira paper bought from someone cared it at bad condition

Does that process refresh them to factory grade again ?

I am not expert and want to be sure whether I found answer for above problems , if we can solve above problems , its a very good deal.

Thank you ,

Umut

 

[winterclock]

Understand that the process cannot completely restore the film, the ray traces were still discernable after refreshing. While I use old film, I use it for the effect of being old film. I have not yet encountered film that is fogged beyond the point I can no longer work with it, so I have not attempted to refresh any of my stock. I doubt that any such process can completely restore 40 year old film. Given that, I believe refreshing would reduce the level of fogging on old paper and film, whether the paper would survive the process is doubtful. With improperly stored film there will probably be some physical damage; shrinking of the gel and or substrate, delaminating, fungal damage, reticulation and discoloration are issues I most often encounter. I do not presently have a way to scan or I would post some examples. Jnanian's work uses older film, look there for examples. I do have some very old Hypan that is probably extensively fogged, when I do attempt to work with it I will try refreshing a few sheets and let you know the results. In the meantime, there is nothing to stop you from trying it out yourself.

 

[Mustafa Umut Sarac]

Hello Winterclock and all,

I pm'ed Photo Engineer , lets see what would he say ?

Umut