“Sweets in the wall” sounds like a folk tale, but a Deccan Herald report highlights real construction science behind traditional Indian lime work. A palm-leaf manuscript preserved at Padmanabhapuram Palace near the Tamil Nadu-Kerala border lists ingredients mixed with lime, including kadukkai, hibiscus, aloe vera, neelamari, eggs, and palm jaggery.
Researchers recreated those preparations and tested them with modern instruments. Their experiments show that fermented organic extracts change lime putty’s physical and chemical behavior. In the Padmanabhapuram testing, jaggery increased lime’s solubility in water and influenced how calcium-carbonate minerals formed, shaping the material’s microstructure as it hardened through carbonation.
Other studies point in the same direction, with important limits. At Hyderabad’s Charminar, researchers analyzed historic lime plaster with tools such as X-ray diffraction, infrared analysis, and electron microscopy. They found organic material, including carbohydrates and proteins. That result supports the broader tradition of organic additives, but it does not prove jaggery was the original ingredient in that monument.
For mason contractors and restoration crews, the practical takeaway is simple: treat existing mortar and plaster like evidence, not legend. A historic masonry wall is a system of units, mortar, plaster, and moisture pathways that has worked as one for centuries. Repairs that behave differently from the original materials can introduce new stress and moisture problems.
When you’re repointing, patching plaster, or developing a repair mix for heritage masonry, focus on compatibility:
Confirm what’s in the existing mortar and plaster before specifying a new mix.
Use testing and mock-ups to validate workability, bond, and curing behavior.
Resist “stronger is better” thinking when lime-based materials are part of the original assembly.
That approach shows up in the field. At Alamparai Fort on the Tamil Nadu coast, researchers developed a restoration mortar using air lime, river sand, and organic additives including kadukkai and jaggery, after first characterizing the historic material. In Delhi’s Nizamuddin heritage area, conservation work has also used traditional lime plaster that includes organic additives.
Read the full, original article from Deccan Herald (subscription required at source) here.