Selecting the correct stone is arguably the most important part of a project and the best way to avoid issues a few years down the line. In one of the earlier ‘Working Face’ pieces, we looked, in a general way, at some key steps to ensure correct stone selection. This time round we will hone in on one specific aspect of this process – what to look for in a stone sample panel. While this may seem like a very niche topic it affects so much of the selection process and deserves a more in depth discussion.
The mine or quarry you source your stone from should have range/control panels showing the geological characteristics typically found in the various beds available (shown below). This provides the architect or specifier with the truest indication of the variation they can expect to find in stone from the bed they are using. This is vital to effective management of client expectations as stone is a natural material and therefore every piece won’t look the same. If this is understood then the unique aesthetic that natural stone provides can be celebrated and built into the design rather than cause tensions between the quarry and the architect.
It is ultimately the quarry or mine’s responsibility to select a suitable number of samples from various blocks from the chosen bed to show the typical range of geological variations that are present in the stone or the bed of stone, but if the production company has already been and selected the stones and the blocks are all in stock and available for a pre‐purchase, then this can be completed at their works instead. Invariably this inspection should take place at the extraction site but if in exceptional circumstances this is not possible, then confirmation that the quarry has been closely consulted in the sample selection must be sought.
The range/control panels from the different quarries and different beds should be carefully inspected and then the final selection should be made and high resolution photographs taken for future reference. There is a fantastic range of indigenous British stone available in a wide variety of colours and textures that offers architects with a unique aesthetic. By following these steps and understanding the expected variations on your material of choice, you will be able to make full use of these natural nuances and in so doing, encourage the client to embrace this uniqueness. The rejection of geological characteristics naturally found in the stone will typically result in increased costs and prolonged procurement through abortive cutting and will increase the wastage thereby impacting on the carbon footprint and the overall sustainability of the supply.