Re: [AV Media Matters] Recovery of AV media in flood disaster

[Mick_Newnham@nfsa.gov.au]

With respect to film (only) I would suggest that the first priority is to
keep the film cold, freezing seems to be OK even for very wet film (I have
tried freezing saturated film, the ice crystals formed do not appear to
leave any permanent blemish on either the emulsion or the base).  This
should be done as soon as possible after the disaster as moulds etc are
ever ready to pounce.

Try to ensure that any identification on the film is maintained (catalogue
numbers etc) and match cans with films if possible.

To dry the film I suggest that the film is rewashed (water based) and dried
using a continuous film processor as found in labs.  The rewashing will
help remove any dirt or contaiminants.  If it is possible the tension on
the machine should be reduced to relieve the pressure on any splices or
damage.  It might be difficult or impossible to repair this damage prior to
rewashing although ideally this should be done.

If the film has been left for a while and has started to adhere ("block")
to other layers in the pack then the film will need to be "unblocked"
before it can be rewashed.  Unblocking involves soaking the film in a
solution that encourages the gelatin to swell (we use sodium
polymetaphosphate 1.5g/l).  The process requires a bit of care with
changing the solution daily otherwise biological action can destroy the
emulsion.
After treatment the condition report needs to be updated etc.

I have looked briefly at freeze drying but not carried out any tests on
motion picture film (so maybe my concerns are unfounded).  Aspects of
freeze drying that I am cautious about are, trapping contaminants in the
film during the drying process, "blocking" induced by the process (probably
treatable) and the cost (although I doubt if any treatment could be called
cheap).

If the film has decomposed to any degree prior to the disaster (Vinegar
Syndrome etc) then the gelatin emulsion will be far more soluble and water
based treatments may actually increase the damage.  In this case maybe
freeze drying would have some advantages.

In the UK, my guess is that the National Film and Television Archive at
Berkhamstead (spelling?) would be a good contact point.

Mick Newnham
Engineering and Research Group
Preservation and Technical Services
National Film and Sound Archive
Australia