Conservation of our built heritage and of ancient monuments is carried out throughout the world. The work ranges from major sites such as the Mayan cities in South America, to the remains of small vernacular structures in Britain. For many years the approach to stone buildings and monuments tended to be to use 'more durable materials' in order to resist the ravages of the elements. Unfortunately this was a very misguided approach and the use of hard weather-resistant stone or cement grouts have often caused major problems and damage to the original fabric. Stone can be a very sensitive material and insertion of materials which may alter the physical or chemical balances which have built up over the years, can cause irreparable damage to the structure.
A policy of 'like for like' replacement should be used when possible, as should an approach which would allow the removal of any repair should it cause deterioration of the original fabric.
In order to undertake sympathetic restoration or conservation, it is necessary to fully understand both the nature of the original materials and the changes which have taken place in them. In stone buildings this involves not only a study of all the different stones used, but also the mortars which were both used originally and which may have been added later. Furthermore, where deterioration of stonework has been found, it is necessary to accurately identify the reason for that deterioration. To merely repair the damage without rectifying the cause, would merely allow the degradation to continue in the original fabric.
Characterising the stonework of a building or a monument can involve a range of techniques, from simple petrographic studies to chemical analyses and the use of the environmental scanning electron microscope to determine the nature of chemical and mineralogical changes occurring in areas, perhaps only a few microns in diameter. We have been undertaking such studies for a number of years, providing information and advice both to national conservation organisations and to architects and conservators. Once the nature of the stone and the mechanisms causing its deterioration have been determined, replacement material of often required. Ideally this should be the original stone.
Identification of original sources and the temporary re-opening of the quarry, is now a procedure which we organise on a relatively regular basis.
Please contact us for further information on the services we can provide.