83 CATHEDRAL COMMUNICATIONS THE BUILDING CONSERVATION DIRECTORY 2024 MASONRY 3.2 assist with better colour matching as well as viewing samples on site in wet, dry, cloudy and sunny conditions, both up close and further away. As well as colour and texture, mortar matching also needs to take into account the hardness and permeability of the original. There are still issues in the conservation industry where inexperienced heritage professionals are not familiar with different mortar types and the damage cementitious mortar can do. In some cases conservation proposals specify the use substitute materials in lieu of terracotta. These fail to match the colour and texture of the original material, particularly as they age. Replacing an historic material with some other material cannot be considered to be conservation work, and is unacceptable in principle. CLEANING TERRACOTTA My research also found that contractors and cleaning specialists are less likely to refer back to Historic England’s guidance either due to time constraints or perhaps because they consider they have greater knowledge on the subject matter through hands on experience. In particular I found that many lack understanding when it comes to cleaning, especially regarding the use of copious amounts of water. Contractors are more than content to use the JOS cleaning method of ‘cleaning to fulfil client expectations’. These amounted to a demand for overly clean buildings, especially in London, which risks damaging the surface of the material. Conservation Officers do not generally seek details of methods of cleaning, leaving contractors to make decisions. They do not question the various cleaning methods and whether the method selected would be harmful to the building. PROFESSIONAL EXPERIENCE AND KNOWLEDGE The conservation industry has knowledge of the subject matter through terracotta projects and practical learning, through academic research and methodologies, and through the work of bodies such as Historic England, the Tiles and Architectural Ceramics Society (TACS), and the West Midland Architectural Conservation Group. Nevertheless, many conservation officers who were approached in the course of the research had limited knowledge and practical experience of the subject matter, and were not seeking details of repairs, replacement and cleaning methods through planning conditions. This leaves architects and contractors to make key decisions, which may or may not be in the best interests of the heritage asset. Few heritage professionals interviewed as part of this research were aware of the current British Standard for conservation, BS 7913:2013 Guide to the conservation of historic buildings. The vast majority also had no knowledge of Historic England training and webinars, nor of the TACS terracotta conference despite it being the single best collection of advice on the subject matter online. Responses from some of the professional institutes suggested that they would prefer to work independently rather than with Historic England. LESSONS LEARNT, IF ANY? Lessons from the past have been partially learnt, especially with regards to the use of chemical cleaning methods and sandblasting, and research continues: Patrick Barry’s research into the importance of fireskin is eagerly awaited as it will provide valuable information for conservation and maintenance in the future. Nevertheless, there is still a long way to go to address inappropriate resin and mortar repairs, poor colour matching new units and the general lack of awareness among many in the sector of current best practice guidance. In his APT Bulletin article “The Manufacture of Terracotta and Faience in the UK”, John Fidler states that terracotta is the least understood material. It seems clear that, if the conservation of terracotta buildings is a wider responsibility within the industry, all professional bodies should be working with heritage bodies like Historic England to promote relevant training sessions to their members. Improved networking across the whole conservation industry is required to better understand the material. This will ensure decisions on repair, replacement and cleaning are made on what is best for the building to safeguard its special character and significance. Signs of progress were obvious at the third terracotta conference, which was held at Birmingham City University in 2023 with the specific aim of promoting better collaboration within the industry. The conference was supported by the IHBC and RIBA with delegates from across the conservation industry, including architects, conservators, conservation officers, heritage specialists, structural engineers and academics. There was overwhelming recognition for the need for a more collaborative practice and the richness that emerges from those conversations, and the idea of a centre of excellence in terracotta to be based in Birmingham was muted and widely supported. Terracotta was once hailed as a wonder material and it is the duty of the conservation industry to treat it in a way that safeguards its survival for future generations to enjoy. DEVINDER MATHARU is a conservation officer based in the West Midlands, born and bred in Birmingham, a city with numerous terracotta buildings. With Katriona Byrne, course director of the MA Conservation of the Historic Environment, she organised the third terracotta conference at Birmingham City University in 2023. Salt efflorescence on brick and terracotta at Belmont Works: saturation by water as a result of poor masonry cleaning can cause efflorescence and crypto- efflorescence within the pores and may lead to the deterioration of the fireskin. An example of new terracotta mouldings with a good colour match for the original work at Newton Chambers, Birmingham
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