Natural stone has been a traditional construction material in Scotland for thousands of years. Due to our varied geology, the wide range of stone types available has shaped and influenced our distinctive national and regional architectural style - it is this distinctiveness that LTM seek to preserve for future generations.
However, stone is a porous material that can be vulnerable to physical weathering. The effects of stone erosion vary depending on the type of stone, its position in the building and the local environment. The condition of the building fabric is also affected by the introduction of incompatible materials, poor detailing and lack of maintenance.
Stone decay therefore affects different buildings in different ways. LTM have extensive experience in identifying the extent of stone erosion and assessing its structural significance and appropriate repair methodology. Our respected LTM teams can undertake the full range of stone repairs, from mortar repairs to full scale replacement and LTM Consultancy can conduct detailed stone assessment surveys to determine the true extent of necessary repair/replacement work.
In addition, our in-house LTM Stone Conservator can undertake delicate consolidation work to historic and decorative stonework. This service is often more appropriate because it ensures minimal intervention of the historic fabric, retaining as much original material as possible. The purpose of masonry consolidation is to halt the decay of the stone itself; techniques include:
- Paraloid B72 Treatment (solutions with acetone and IMS - methanol)
Paraloid B72 is recognised in the conservation industry as a consolidation agent for natural stone. It is injected via a syringe to impregnate small cracks and fissures, or alternatively used as an acrylic mortar repair. It is appreciated by conservators because it is easily reversible and doesn’t stain the stone if it’s used properly.
- Silanes Treatment (e.g. alkyl-trialkoxy-silanes)
Silane-based materials are recommended as a surface consolidant for disintegrating natural stone. It is applied onto the dry stone surface in the form of a solution in alcohol, which must evaporate before hydrolysis and polymerisation can occur. The end product of polymerisation is silica, which is present as a cementing mineral in many types of sandstone. It is favoured by conservators because there is a definite consolidating effect and penetration can be relatively deep, depending on the product used and the conditions in which it is applied.