Lime plaster - Heritage in every layer

Lime Plaster
With the eye-catching, high-tech materials of our times, it’s not hard to forget the humble, tried-and-true methods that constructed our cultural heritage. One such ancient solution is lime plaster—a basic combination of lime, sand, and water that has adorned the world’s most beloved buildings for centuries. Beyond a mere wall finish, this venerable material is a triumph of human innovation, one with depthful historical, architectural, and environmental significance.

Composition and Types of Lime Plaster
In essence, lime plaster is a result of a lovely, slow alchemy. Its simple ingredients are deceptively straightforward: lime (made from calcined limestone), sand as an aggregate, and water. But the quality of the lime dictates its nature and uses.

Non-Hydraulic Lime Plaster (Lime Putty): This is the most pure, being made from slaked quicklime. It undergoes a process known as carbonation, gradually reabsorbing carbon dioxide from the atmosphere. This creates a soft, vapour-permeable plaster that is very flexible, which suits historic buildings that need to move and breathe.
Hydraulic Lime Plaster: With impurities that enable it to harden in the presence of water, hydraulic lime plaster is stronger and harder, even in wet conditions. Its hardness can vary, enabling conservators to closely approximate the properties of the original mortar.