In the past, gypsum was one of the most important building materials in the region around Koya. However, due to the use of cheaper cement, it has almost fallen into oblivion as a mortar, a problem that current restoration projects in the Old Town of Koya are struggling with. Nowadays, gypsum is only used as gypsum plaster, which requires a different, simpler production method. The General Director of Antiquities and Heritage, Kaify Mustafa Ali, the Department of Antiquities in Koya (Yekaty Wahip and Hemin Kawez), WADI e.V. (Anne Mollenhauer) and Klessing-Hoffschildt Architects (Andreas Hoffschildt), have therefore begun to revitalize this old craft tradition with the generous support of the German Gerda Henkel Foundation. In March 2024 a survey of the quarries in the region was conducted, in cooperation with the University of Koya (Manar Ahmad), the University of Dohuk (Shireen Younis) and geologist Michael Krempler, to select good quality quarries near Koya City that also have adjacent, unused plaster kilns. A firing site near Koya, which also has a rich quarry, was selected. Three combustion chambers were repaired together with an experienced old gypsum burner, and a new gypsum burning process was started on an experimental basis. The aim was to burn plaster at high temperatures and to achieve a broad distribution of fine and coarse particles in the grinding process. The analysis of historical plaster mortars from the Mahmud Agha Khan in Koya (1860 A.D.) gave us the parameters that now had to be achieved experimentally; local experience of firing plaster at high temperatures has been dormant for many years - Kak Salim, for example, has not worked in this field for over 20 years. The challenge began with the purchase of the necessary equipment: an old truck whose drive shaft operating the stone mill, the restoration of an old stone mill that had been unused for many years, the correct adjustment of the burner: a mixture of diesel and waste oil, the flame of which is regulated with the help of compressed air. The firing process itself takes one day (approx. 9-10 hours) the stones piled up to form a false vault were fired, followed by a day for cooling, and on the third day the stones were ground and packed in bags. For long-term observation, we rebuilt a destroyed rear wall of the khan, which now serves as an open-air test area. Four weeks later, the plaster was already being put to practical use: The Department of Antiquities in Koya began restoring the Malai Gawra house in the old town and immediately used the new gypsum mortar, much to the delight of the masons involved, who praised its quality highly. The analyses and tests carried out in Germany and Koya confirmed the quality of our new mortar, even if it did not initially reach the values of the historical mortar samples taken from the Khan, but long-term monitoring showed that after six months we almost achieved the values of the historic gypsum mortar.