The Triton Stone Library |
Having established that none of the samples in the Triton Stone Library could offer a good match to the stone used in the subject building, the next step was to obtain samples of stones that might be suitable to undertake the necessary repairs.
E-mails were sent off and phone calls made and I soon
discovered that the quarry, which has been considered to be the primary source
of this stone, has now been mothballed and that I would need to search elsewhere
for a good match.
Stone matching in practice... |
Time is of the essence, when planning and scheduling an extensive programme of works in the building restoration industry, and the first samples of stone were sent by a tried and tested contractor, who has a good working knowledge of the region.
The samples of Oat Hill
stone from the recommended alternative marketed by various companies finally
arrived, but a quick inspection with a hand lens revealed a medium grained, shelly oolite - with voids - which bears little resemblance to
the subject stone.
The Art of Stone Matching is based on deep geological knowledge, and an understanding of chemistry - but it also relies on intuition, which microscopic analysis just can't reproduce.
This particular compact, fine grained, moderately well sorted oolitic limestone is left with a very distinctive iron stain when subjected to a standard hydrochloric acid test.