This guidance is aimed at conservators and those specifying conservation treatments for historic stonework. It will also be of interest to conservation officers, and building owners and managers. Although the past ten years have seen an increase in the use of nanolime as a stone consolidant, not much was known about its properties and performance, and there had been no long-term evaluation of its effect on deteriorated limestone in an external UK environment. Furthermore, there was no consistent guidance regarding application of nanolime. For these reasons, Historic England...