8.5 What are some recommendations for long-term film storage?
Description
This article is from the rec.arts.movies.tech FAQ, by Scott E. Norwood snorwood@nyx.nyx.net with numerous contributions by others.
8.5 What are some recommendations for long-term film storage?
Two opinions from a rec.arts.movies.tech thread:
Subject: Re: Vitafilm availability and film cleaning
From: jharw91601@aol.com (JHarw91601)
Date: 1996/10/23
Newsgroups: rec.arts.movies.tech
[snip]
There is no known cure for vinegar syndrome. There are many "wive's
tales" out there, but none of them has had any scientific backing as of
yet.
What causes vinegar syndrome? Well, there are many. The most common
cause is improper storage in overly humid environments. Other causes are
poor processing and some types of scratch rejuvenation.
So what are molecular sieves? They are small packets which are placed in
the cans of deteriorating film. They absorb most of the acetic acid
vapors which are being released from the film base. These vapors (which
smell like vinegar) are what attack the emulsion as well as the plastic
acetate base support. If the sieves are used in tandem with proper cold
storage (below 50 degrees F and 40% relative humidity) then this will slow
the deterioration down to a crawl.
[snip]
Cleaning your film with commercial film cleaners should be limited to
those which do not have any oils in them, if you're cleaning films with
vinegar syndrome. Trichloroethane based cleaners, or just straight
trichloroethane, is very good. Ecco brand and J&R Film cleaner are good.
Vitafilm and Surfaset have silicons &
oils in them. Oils tend to trap in the acetic acid vapors, which will
hasten the deterioration. Make sure you use a clean velvet or Webril Wipe
when doing a cleaning. Unless the print is dirty, however, it's best to
leave well enough alone. Passing a film through a cloth can potentially
cause scratches. Be very careful to stop periodically and shake out the
rag in case dirt builds up in it.
[snip]
Sincerely,
Jim Harwood
_________________________________________________________________
Subject: Negative Storage
From: fwylie@infinet.com (Frank Wylie)
Date: 1996/10/25
Newsgroups: rec.arts.movies.tech
bihari@ohstpy.mps.ohio-state.edu wrote:
>I have heard conflicting advice on the best method for long term storage of
>film negative. Room temperature, cool, or frozen?
> What humidity is best?
Jim,
The National Film Board of Canada has begun tests on freezing monopack
color negs, but beyond that I couldn't tell you the long-term effects
of freezing your negative. Some members of the AMIA-L (Assoc. of
Moving Image Archivists) listserv expressed concern that if the
proceedure was not carried-out with great control, then the base,
emulsion or both could be fractured by the excessive moisture content
of the emulsion, due to expansion of the freezing water. There were
other issues as well, but I don't remember them off-hand.
At the present time, I believe the consensus is that the optimal
storage temperature is near, but not below, freezing with a relative
humidity of 30 - 40%.
>Will dessicants in the film cans dry out the film too much?
In a word, yes. Unless you are storing the film in a very humid
place, I would not put sillica gel in the cans. If you are storing
the film in a humid environment and cannot control the atmosphere in
any other way than using sillica gel; store the film in an oversized
can, on cores and laying flat (you should always store film on cores
and laying on-edge - never store on reels and in the upright
position). I would suggest you attach the gel canister to the can lid
with pop rivets (or other non-chemical based method to avoid harmful
adhesive fumes) over the center of the core. If you lay the packet in
on top of the roll, you may cause the film to dry-out in the area
direcly beneath the gel and cause dimensional problems in the future.
Check the canister and gel every two-weeks and turn the roll over to
equalize the absorption across the web of the film. I really don't
know how you would monitor the relative humidity of the can, but a
stable atmosphere is critical. Cycles of humidity and extreme dryness
can cause severe stress on the emulsion; causing fractures, across
the web shrinkage and maybe even vinegar syndrome. Who knows?
Also, don't store film in tight-fitting cans; let it breathe. Safety
has a tendency to go vinegar if sealed-up in a can (not so much if the
temp is low), so keep the film in loose-fitting, oversized cans.
If you can afford it, throw in a few molecular sieves per can; can't
hurt (at least as far as we know!).
> I definitely appreciate Jim Harwood's helpful post. If the ideal
>condition is below 50 degrees at 40% relative humididy, would it be a
>good idea
>to devote a refrigerator to storing my original negative for my films?
I think so. The greater volume of air would be easier to stabilize and
maintain a good relative humidity level. A fairly inexpensive weather
station (indoor/outdoor type) could be mounted on the door to keep a
check on the interior without opening the door. I would NOT suggest
you use a "frost-free" type of refrigerator, as they remove humidity
to keep-out frost and could freeze-dry your film. If the fridge tends
to keep a dry atmosphere; put a few damp rags in a film can, punch a
few holes in the top and place it in the bottom of the refrigerator.
If too damp, use sillica gel cansiters to lower the RH. You will have
to experiment to find a method of regulation, but it should not be too
hard.
>freezing it worse than refrigerating it? Will the wrong temperature or
>humidity wreak havoc (sp?) on glue splices?
At the present time, I would say cold storage, but don't freeze just
yet. Until more testing is conducted, try a method that has had some
success in the past.
As for the splices; they would be my least worry. A cement splice
can be remade without too much fuss; and without loosing a frame. I
would worry about fungus, mold, air pollution, solvents and other
nasties attacking the emulsion; along with the natural tendency of
dyes to fade over time.
The biggest problems in preservation of color negative are:
1. Dye fading - solution: copy when dyes start to fade. That's
about all you can do. Forget digitizing; the storage medium won't
last as long as the original negative and "Who the heck can afford it
anyway ?".
2. Shrinkage of base - solution: maintiain proper humidity and temp.
Make new dupe preservation neg when approaching 0.5% linear shrinkage
of the film. Shrinkage should be measured over the length of one-foot
of film and expressed as a percentage of the total original distance
on a fresh piece of properly-pitched stock (get the right pitch, it
matters!). We use shrinkage-gauges built by Mauer in the 50's; I
don't know what to suggest for a homebrew measuring device. You start
having printing problems (movement and breathing in the printer gate)
at about 0.6 % on "standard" printers. When you exceede that amount,
you have to have it printed on a modified printer; one with the
sprocket teeth cut-down and movement is almost assured when you print
that way.
3. Emulsion damage - don't handle the film excessively, but do
exercise the roll at least once a year by rewinding. Some claim you
should store the film emulsion-in (contrary to lab practice!), but we
at the LOC store all our originals emulsion-out. Why? I guess it's
just easier to handle when printing when would emulsion-out.
4. Environmental damage - Solvents, ozone, gases, etc. attack the
base, emulsion or both. Keep storage areas clean and free from
volatile chemicals and or liquids.
Whew! Hope that helps somewhat.
__
S. Frank Wylie
fwylie@infinet.com
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