What happens to the fabric of a historic building if it is not cleaned? What is soiling, how does it affect the building? What cleaning methods should be used? This first of a comprehensive two-volume guide addresses these important and controversial questions, along with many others, and offers practical guidance on appropriate cleaning techniques, backed up with useful case study material. Based on the author's extensive on-site involvement at trial and contract stage in many cleaning and surface repair project, this book examines the various attitudes and current cleaning practices, along with the role and need for analysis of substrates and soiling. It also offers advice on dealing with special cleaning problems, such as the removal of paint, graffiti and metallic stains, and provides an assessment of the cleaning methods currently available