Patching terracotta glaze

Peter Wollenberg <wbconservation [at] sbcglobal__net> writes

>Has anyone else used Edison products to patch damaged architectural
>terra cotta glaze? What coatings have you used to replicate matte
>glaze color and texture? Have you used coatings other than those
>made made by the patching manufacturer?

We would be very interested in any responses to this, we are
currently undertaking repairs to some external faience here in the
UK and have spent many months looking into suitable materials.  We
have rejected proprietary patching mortars, as they mostly do not
stand up well over time (there is scant decent scientific research
on these) and are often epoxy based, discolouring or failing at the
bond between repair and original material.  We have returned to
using a well-matched fine cement mortar for repairs, and find this
works successfully.

With regard to coatings, we are currently undergoing testing
processes for a number of glazes (we need a high gloss coating that
must not discolour), however our initial tests suggest a lifespan of
only 5-8 years.  We have struggled to get a response from Edison
despite emailing and telephoning, it appears we may be too far over
the water to warrant their interest(?).

Berenice Humphreys
Cliveden Conservation
Home Farm
Ammerdown Estate
Kilmersdon
Bath BA3 5SN
UK
+44 1761 420300


                                  ***
                  Conservation DistList Instance 21:28
                 Distributed: Friday, October 26, 2007
                       Message Id: cdl-21-28-008
                                  ***