Conservation of archaeological composite object

The ADC (Archeologisch Diensten Centrum, Archaeological Service
Centre) carries out archaeological excavations (large
infrastructural as well as small-scale) in the Netherlands. On one
of our larger projects, the Roman military site Vleuten de Meern
Wachttoren, the following composite object was found: a piece of
wood in an iron "shoe". We think that it might be the lower end of a
lance/spear or even a Roman "signum". The wooden part, approximately
35 cm long and broken in 5 pieces, is attached to the iron "shoe"
with 2 crossed nails (visible with X- radiography).

The object has undergone some conservation treatment about 3 months
ago, in which the wood has been repaired and the iron has been
cleaned mechanically and covered with a layer of wax. The iron
"shoe" has not been desalted which has most likely caused the iron
to start corroding again. Other iron artefacts of this excavation
show the same signs of renewed corrosion: small spots of
reddish/orange corrosion products all over their surface. Therefore,
they will have to be treated again in a way that as much chlorides
as possible will be removed.

The archaeological conservator is suggesting to apply high
temperatures at the objects to drive off the chlorides. The
difficulty we are facing here is with the composite object. The
project leader is very eager to not separate the wood from the iron,
but it seems to me that separating the two materials is inevitable
when having to desalt the iron.

My question is: would any one of you know of a method to desalinate
a wooden/iron composite object without having to take it a part?
What objections might there be or not be in separating the wood from
the iron for the treatment? What would be a suitable solution for
this conservation problem? All suggestions are welcome.

Karin Abelskamp
Conservation Coordinator
Archaeological Service Centre (ADC)
Bunschoten, the Netherlands


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                  Conservation DistList Instance 15:31
                Distributed: Wednesday, October 10, 2001
                       Message Id: cdl-15-31-006
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