Jackfruit Wood Plank & Unbleached Cloth Chalk Gesso Sizing in Tanjore Painting

In traditional South Indian sacred architecture and craftsmanship, the jackfruit tree (Artocarpus heterophyllus, known in Tamil as Pala Maram) occupies a revered position alongside teak and sandalwood. In the creation of authentic Tanjore paintings, jackfruit heartwood is the undisputed material of choice for the Palagai (wooden board).

Jackfruit wood possesses a rare combination of physical properties ideal for supporting heavy gesso and gold leaf. It has a moderately high density (around 590–650 kg/m³), fine interlocking grain, and remarkably low shrinkage coefficients across seasonal changes. Most importantly, the mature heartwood contains high concentrations of natural polyphenols, flavones (such as artocarpin), and sticky latex resins that render it naturally repellent to termites, carpenter ants, and fungal decay. This ensures that the structural foundation of a sacred icon remains intact across centuries of tropical monsoon cycles.

Direct application of mineral gesso onto bare timber is disastrous: as the wood expands and contracts with changes in ambient humidity, the rigid gesso cracks and delaminates. To solve this, Tanjore masters devised an ingenious decoupling system: wrapping the board in tightly stretched, unbleached handloom cotton fabric (Kada cloth).

The adhesive used to bond this fabric to the wood is tamarind seed paste. The brown seeds of the tamarind fruit (Tamarindus indica) are roasted to loosen the outer shells, after which the creamy white kernels are soaked in water and boiled into a thick, translucent starch gel. Unlike modern synthetic glues that become brittle and crystalline over time, tamarind seed xyloglucan remains remarkably flexible and cohesive. To safeguard the organic paste against tropical mildew and silverfish, craftsmen incorporate a trace amount of powdered copper sulphate (Mayil thuthu) or crushed neem leaves, creating an all-natural, permanently insecticidal bond.

Once the cotton cloth has dried drum-tight over the board, the artisan prepares the drawing ground, traditionally referred to as Mucko. The recipe consists of high-purity French chalk (precipitated calcium carbonate or finely ground soapstone) blended with a binder of dissolved gum arabic (harvested from the Acacia nilotica, or Babool tree).

The chalk provides pure white opacity and dense mineral body, while the gum arabic imparts toughness and controlled porosity. The mixture is ground meticulously on a granite stone mortar until it attains a silky, lump-free consistency. If the binder concentration is too high, the ground will crack as it dries; if too low, the surface will be chalky and weak. Master painters calibrate the ratio by feel, creating a gesso that flows smoothly under the brush while drying into a resilient stone-like layer.

The application of Mucko gesso is executed in four to five successive thin coats. The artisan applies each layer in alternating perpendicular directions—first horizontally, then vertically—allowing each coat to air-dry thoroughly before the next is brushed on. This cross-hatching ensures uniform thickness and bridges any micro-weave texture of the underlying cotton cloth.

After the final coat cures for 48 hours, the surface undergoes rigorous polishing. Rather than dry sanding, which produces airborne dust and micro-scratches, traditional masters perform wet sanding using fine waterproof emery paper (400 to 600 grit) or smooth river stones lubricated with a damp cotton sponge. The artisan sands in gentle circular motions until every brush mark and irregularity vanishes, revealing a luminous, bone-white ground as smooth and non-porous as polished marble, ready to receive delicate iconographic line work.