Dr E. Ramanathan
The Secret Ingredients: Rediscovering the Science and Soul of India’s Traditional Architecture
India’s architectural heritage, from the prehistoric rock shelters of Bhimbetka to the intricate carvings of medieval temples like Ajanta and Ellora, stands as a testament to ingenuity and sustainability. Yet, the true marvel often lies not in the grand structures themselves, but in the sophisticated, forgotten sciences that allowed them to endure for millennia. These traditional building methods, which seamlessly blend natural resources with scientific principles, are now the very focus of modern conservation efforts.The Earth’s Palette: Historical Pigments
The vibrancy of India’s ancient wall paintings was achieved through a simple yet powerful palette of natural, inorganic minerals. Painters relied on:
- Ochres for deep reds (hematite) and vibrant yellows (goethite).
- Wads (manganese) for blacks.
- Green earths (celadonite and glauconite).
- White earths (calcite, gypsum, and kaolinite).
These paintings were traditionally executed using tempera (binding pigments with animal glue or plant gums) or secco (painting on dry lime plaster). Today, conservationists use advanced analytical techniques like X-Ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Fourier Transform Infrared Spectroscopy (FTIR) to precisely identify these pigments, study their crystalline structures, and understand their degradation patterns.The Alchemy of Additives: The Science of Superior Mortars
For centuries, Indian builders were masters of material science, incorporating natural, organic additives—such as plant extracts, jaggery, animal glue, and egg whites—to dramatically improve the structural properties of simple lime mortars.
Experimental research confirms that combining fermented palm jaggery and gallnut (Kaddukai) significantly boosts the mechanical properties and durability of Class B hydraulic lime mortars. This is chemistry in action: the jaggery (predominantly sucrose) reacts with the calcium carbonate in lime, forming exceptionally strong bonds that can increase compressive strength by up to 200%. Furthermore:
- Jaggery vastly improves waterproofing and reduces water absorption.
- Gallnut aids in early carbonization.
Together, these additives create a denser internal microstructure and provide excellent resistance against cyclic salt weathering and acid attacks.Regional Secrets: The Art of Traditional Plasters
The diversity of India’s landscape is reflected in its plastering techniques, each adapted to local resources and climates:
- Rajasthani Plasters:
- Thappi is a base plaster of slaked lime, crushed fired clay (surkhi), and sand, mixed with fermented jaggery and fenugreek water, then aggressively beaten for homogeneity.
- Araish is a high-gloss, mirror-finish topcoat made from extensively slaked lime purified with curds and mixed with marble dust, which is then meticulously burnished with a semi-precious agate stone until shiny.
- South Indian Plasters:
- Madras Chunam achieves a waterproof, glossy finish by grinding a paste of lime and sand with egg whites, curds, and ghee butter in its final coat.
- Chettinad Plaster involves six thin layers of slaked lime and white stone powder (kalmavu), utilizing whisked egg whites or tallow in the final coat to yield a highly reflective, crack-free surface.
- Earthen Plasters: In Kerala, mud plasters utilize the bark and leaves of the ooravu tree to create a sticky binder. Final protective coatings often rely on extracts from castor leaf, Indian bael fruit gum, or neem tree gum to seal the surface and prevent dustiness.
The Imperative of Ethical Conservation
Preserving these marvels demands strict adherence to ethical and scientific guidelines, notably the Venice Charter, which mandates the reversibility of conservation processes and the retention of original patina.
Conservation manuals dictate that modern materials like cement must be avoided. Instead:
- Restoration uses traditional combination mortars (lime, sand, jaggery, gallnut, and aloe vera for anti-saline action) to replaster walls and grout cracks.
- Structural Repair involves removing excess dead weight from faulty modern repairs (like concrete beams) and replacing them with traditional teak wood wrapped in lotus leaves and coir ropes.
Crucially, experts strongly condemn destructive practices like sandblasting, which ruins the protective skin of granite stones, destroys intricate sculptures, and weakens ceilings. Safe chemical cleaning using liquid ammonia is prescribed as an alternative. Even modern tools, such as rotary drills, are employed cautiously only to safely extract fragile artifacts—like Amaravati limestone sculptures—without causing damaging vibrations to the main structure.
This commitment is formalized by government initiatives, such as the Hindu Religious and Charitable Endowments (HR&CE) Department of Tamil Nadu, which mandates empanelled experts to use scientific preservation methods in conformity with Agama and Shilpa Shastra principles, ensuring that the brilliance of India’s architectural past remains intact for future generations.
