Kahgel plaster has been a common method for protecting architectural structures at the Takht-e Soleyman World Heritage Site. Primarily applied to stone and brick structures, this plaster has proven inadequate in the site's mountainous, high-rainfall climate with sub-zero temperatures, leading to significant erosion. This study investigates the potential of replacing Kahgel plaster with traditional half-baked, half-crushed gypsum plaster as a protective coating for walls and architectural remains. The aim is to prevent moisture penetration while minimizing the new coating's own deterioration. Field research, including observation and documentation, was employed to gather data. Results indicate that the use of traditional gypsum mortar as a restoration material at the site has been successful. Derived from pounded and crushed kiln-fired gypsum stone, this mortar exhibits similar characteristics to the original mortars and offers adequate strength in the region's harsh climate. Consequently, it presents a viable sacrificial coating alternative to Kahgel plaster.