Paper damaged by seawater

Kaname Shimada <shimada [at] hozon__co__jp> writes

>As a result of the Great East Japan Earthquake on March 11, 2011,
>Japanese paper and book conservators are struggling with the rescue
>and recovery of paper-based objects that have been fully or
>partially soaked, or moistened with seawater. ...
>...
>A survey of published conservation literature has not provided any
>information regarding the recovery of such objects, including
>information related to the long or short-term effects on paper
>following exposure to the contents of seawater.

When I worked for the Canadian Conservation Institute (I am now
retired) we were occasionally asked by the Transportation Safety
Board of Canada to vacuum freeze-dry aircraft logbooks (and
sometimes ship's logbooks) that had been immersed in sea water as a
result of an air crash or ship sinking.  What we found was that the
salt in the sea water was extracted during the vacuum freeze-drying
and collected as a lump of ice in the condenser of the freeze-drier.
The documents still smelled of sea water, but airing out afterwards
usually eliminated the smell. If there were salt deposits on the
surface of the paper these could be brushed off with a soft brush.

I would suspect that by now all the documents are dry, so I doubt
that there is any point in freeze-drying at this stage. It is also
very expensive. Mud, slime and mould can be brushed off under
controlled conditions (i.e. in a Level 2 biohazard chamber, or a
fume hood, or outside if neither of these is available). I would be
leery about rewetting these documents without testing for solubility
of inks first; also, rewetting runs the risk of moving the mud and
slime around on the paper, and possibly driving them into the paper.
Therefore, if everything is now dry I would suggest brushing and
vacuuming dirt, mud, slime, mould using a combination of soft and
semi-stiff brushes, and a vacuum cleaner fitted with a HEPA filter.
Freezing (at -20 deg. C or colder) should arrest the mould problem.

Once the documents are cleaned, test the inks for solubility (if
they are soluble the chances are that many of them will already have
run). If the inks and the paper are stable then it may be possible
to rewet and wash them. Remember, prolonged wetting and mould can
severely weaken paper, therefore documents should be supported at
all times on Pellon or Reemay polyester support material. If the
paper is typical Japanese paper and very fibrous I would suggest
using Pellon instead of Reemay since paper fibres tend to stick to
Reemay and can be pulled off.

These are just my thoughts, as a former paper conservator, and not
those of the Canadian Conservation Institute.

David Tremain


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                  Conservation DistList Instance 25:4
                   Distributed: Monday, June 27, 2011
                        Message Id: cdl-25-4-006
                                  ***