1Traditional mortars are eminently workable, effectively porous, economic in use and appropriately durable. Used in buildings for thousands of years, these materials are ideal for repair and conservation work. Unlike cement or modern hydraulic lime, their routine use would make a significant contribution in the struggle against climate change. However, despite the 1975 'lime revival' there remains a deficit in research into the most-used traditional mortars. This book seeks to redress the balance. Drawing upon historic literature, material science and industry case studies, topics covered include: a historical overview of traditional mortars; slaking and mixing hot mixed lime mortars; the essentials of pozzolans, aggregates and lime tempering; plasters, lime washes and sheltercoats, and finally, the revival of interest in the use of like-for-like and compatible mortars.