Great Bath Waterproofing Material

The Great Bath, an important structure from ancient civilizations (often associated with the Indus Valley Civilization, specifically Mohenjo-daro), required effective waterproofing for its walls and floors.

Material Used for Waterproofing

Historical and archaeological evidence suggests that Gypsum was used as a primary material for waterproofing the Great Bath.

• Gypsum, when heated, forms Plaster of Paris, which can harden effectively.
• It was often mixed with other materials like lime or bitumen to enhance its sealing properties.
• This layer created a barrier preventing water from seeping through the porous brickwork of the bath.

Why Gypsum Was Chosen

Gypsum offered practical advantages for waterproofing ancient structures:

• It was a readily available natural resource in many ancient regions.
• When processed correctly, it formed a relatively impermeable layer.
• Its ability to set hard made it suitable for sealing surfaces like walls and floors.

While other materials like lead or copper were used in antiquity for various purposes, and lime was a common building binder, the specific application for waterproofing the Great Bath is strongly linked to the use of processed gypsum.