The Abu Dhabi Authority for Culture and Heritage (ADACH) is implementing a plan to maintain four historic stone buildings in the old town in Dalma Island. These buildings are Al-Merikhi House (or the House of Pearl Merchants), and the mosques of Al- Merikhi, Al-Dosari, and Al-Mohannadi. Dating back to 1930, the four buildings have coral stones and ornate mortar. They reflect the wealth of pearl merchants. Pearl trade was the main source of living in the Dalma in the nineteenth century and early twentieth century. The recent restoration plans, which are carried out by ADACH and its consultants, include the study of the history and conditions of the four buildings and the materials used in their construction and restoration in order to develop strategies for restoring, managing, and enhancing their performance in the future. These strategies are aimed at restoring the buildings and maintaining their originality in a way that would keep their historical architectural shapes, using restoration materials consistent with the historic structure of the buildings. The Department of Conservation at ADACH said that, despite the decline in pearl extraction from the Island of Dalma after World War II and by the late 1980s, the buildings have become in a deplorable condition, with the exception of a mosque that was still frequented by worshipers. Between 1993 and 1994, the four buildings were restored and Al- Merikhi House was turned into a museum. However, the coral stones and gypsum used in the original construction process and the subsequent restoration works contained a big amount of salts, which caused huge damage to the buildings and their foundations. The problems of construction, termites, and the humid marine environment contributed to the deterioration of the facades and wooden components, such as doors and ceiling bars. ADACH stresses the necessity of being very careful when making any decision related to the selection of restoration materials. If used materials are selected wrongly, the building may be subjected to the same damage it had in the past. That decision should be based on a thorough scientific analysis and a careful study of the historical structure, in addition to verifying the restoration materials likely to be used. After completing the restoration management plan at ADACH this year, work began on the ground to determine the source of mortar and gypsum and test them in order to support the balance in the weak walls of the Al- Merikhi House which decayed due to moisture and salt. The restoration of this weak layer requires removing a large layer of weak mortar and replacing it with a new and more established one in order to allow moisture to pass through walls without damaging them. A thorough scientific analysis and a careful study were conducted on the structure of the original building, the patterns of deterioration, and the materials likely to be used in the mortar. In order to determine the appropriate mix of new mortar, more than 20 samples were tested on the location. These samples consisted of lime, sand, and saruj (a traditional material resistant to water and produced in the UAE and Oman). The preparation of multiple samples allows restoration specialists to test a number of factors, including the degree of durability, colour, and sticking to the wall, thus choosing the best mix for future restoration works. The best mortar will be used in restoring the weak walls and repairing the cracks. It will probably also be used in repainting the facades. Moreover, the new drainage systems, dealing with termites, and repairing the facades and ceilings will ensure the stability of all buildings on the long term and will protect the historic buildings from damage. Attached pictures: 1. Al- Merikhi House (or the House of Pearl Merchants), and the mosques of Al- Merikhi, Al-Dosari, and Al-Mohannadi (clockwise from top left) 2. The damage in Al- Merikhi Mosque. 3. In each bar, different types of the mix were prepared to fill the joints between the units of coral stones (from the bottom G, H). Several types of mortar mix were selected as scratchable layers (from the top I, G, and J) and final layers (from the top H). These samples were monitored and evaluated on the basis of their effectiveness, cohesion and colour. 4. After removing the damaged gypsum carefully from the base of the wall in Al- Merikhi House, strips of mortar were put for testing purposes.