Lime plaster

I wondered if anyone had light to shed on the use of different and
effective seals for lime plaster.  I use black olive soap.  I
understand that the water repellency of this soap is because of
oleic acid.  I believe that this has been used on the facade of York
Minster to protect the limestone from the effects of pollution and
acid rain.  Has this worked?

There is a 17th century french recipe for mixing Marseilles soap,
lime sinter water and silicic acid (am I right in understanding that
silicic acid is water glass?) but I cannot find the quantities
involved to create such a polishing soap.  Does anyone know the
necessary quantities of each product?  This is water repellant but
still allows the lime plaster to breathe.

Finally has anyone found a natural substance that will repel oil on
lime plaster?

Miles Negus-Fancey
Mobile: +44 7946640887


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                  Conservation DistList Instance 28:14
                Distributed: Saturday, September 6, 2014
                       Message Id: cdl-28-14-014
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