Consolidant for sandstone

Mark Vine <vpackthread [at] aol__com> writes

>Dara Zitzmann <d_zitzmann [at] yahoo__com> writes
>
>>We will be working on a sandstone monument that has severely
>>deteriorated.  We need to consolidate the stone, however as it is
>>located in Washington DC, we cannot use Prosoco's Conservare OH.
>>Does anyone on the DistList have suggestions for an acceptable
>>sandstone consolidant that can be used in the District?
>
>Primal B60A (also known as Rhoplex B60A) has been used for this
>purpose.

Sandstone crumble is caused by high salt content periodic
re-crystallisation.  To save the object, it is not sufficient to
consolidate as this does not alter the salt content in the stone
behind the consolidated layer. Primal may well be salt-stable but
the stone is not. Salts will continue to act behind any such
consolidation and detach all the consolidated layer.

The only acceptable consolidants are lime water or ethyl silicate as
they are permeable and can thus allow extraction of the salts after
consolidation. This can today be done with a new poultice named
Westox Cocoon. Acrilic consolidation is disastrous as is it
waterproofing and does not permit subsequent salt extraction.

Edgardo Pinto Guerra
Sarteano, (Siena) Italy
Honorary Inspector, Ministry of Cultural Heritage


                                  ***
                  Conservation DistList Instance 20:19
                  Distributed: Monday, October 9, 2006
                       Message Id: cdl-20-19-003
                                  ***