Specifying the right repair methodologies and materials is critical in achieving a successful stone conservation outcome. Ultimately, quality control on a stone conservation project is entirely dependent upon the quality of the Stonework Specification. Jasper Swann provides Stonework Specifications that will ensure an outcome of the highest quality.
Selection of Stone
Using the ‘right’ stone for any given stone conservation project is critical to its successful outcome. Determining what may be the ‘right’ stone involves assessment of a number of significant criteria – some physical, some aesthetic, some pertaining to significance, some to supply. A thorough analysis of these criteria enables determination of what would be the most compatible available stone. Building owners may feel reliant upon a contractor’s advice when it comes to deciding which stone to use. As some contractors may also be suppliers, results may not be as good as they might have been. The interest of the client can be protected by gaining an independent assessment of what might be the best available compatible replacement stone.
Jasper Swann has no affiliations with any commercial suppliers of sandstone and offers an impartial assessment of what may be the best available compatible replacement stone to use on any given stone conservation project. In making this assessment, the following criteria are considered.
Physical test results for:
- Bulk density
- Compressive Strength
- Flexural strength
- Water absorption
- Resistance to salt attack Durability/ Weathering Capacity
- Compatibility with existing stone
- Location of the building and location of the new stone within the building
- Colour (including capacity to self-colour, or to be responsive to proven artificial colouring techniques)
- Surface texture
The issue of what type of mortar to use in any given stone project is one of great importance. The use of inappropriate mortar has been widespread over many decades, with a range of unfortunate and harmful consequences for historic stonework. Jasper Swann can advise on which mortar to use on any given project, in consideration of the individual requirements of the job. Lime mortars, in particular, are extremely useful when working with stone – both new and old. Selecting the right mortar is as important as selecting the right stone.