Chancel slab

During the last summer archaeological campaign, carried out from the
Studium Biblicum Franciscanum on the byzantine site of Umm al-Rasas
(Jordan), I had to restore a sculpted chancel slab (approximately
120 x 70 x 10 cm.). This artwork, carved in bituminous schist, was
broken in several sherds and chips and many micro-clefts could be
seen along the fracture lines. With different and stronger stones, I
had to use, besides a normal epoxy resin, some fiberglass pivots.
But, the problem here was the remarkable tenderness of the schist,
such as the presence of the micro-clefts. The risk was, in fact, the
opening of these clefts during the hole-making with the drill.

So,I limited myself to glue the sherds with Araldite LY 554 (over an
operational stratum of Paraloid B 72 at 10% in acetone), but I'm not
satisfied about the resistance of this intervention, even if we
decided to lay the slab in a metal frame for expositions.

Since I'll probably restore other ten slabs of the same material,
I'm looking for any information about such kind of works, i.e. if
the risk I was fearing is real or not

Giulio Montinari
Sal S.M. della Sanita 68/6
16122 Genova, Italy

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                  Conservation DistList Instance 12:26
                Distributed: Tuesday, September 15, 1998
                       Message Id: cdl-12-26-010
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